FFPROBE-ALL(1)FFPROBE-ALL(1)NAME
ffprobe - ffprobe media prober
SYNOPSIS
ffprobe [options] [input_file]
DESCRIPTION
ffprobe gathers information from multimedia streams and prints it in
human- and machine-readable fashion.
For example it can be used to check the format of the container used by
a multimedia stream and the format and type of each media stream
contained in it.
If a filename is specified in input, ffprobe will try to open and probe
the file content. If the file cannot be opened or recognized as a
multimedia file, a positive exit code is returned.
ffprobe may be employed both as a standalone application or in
combination with a textual filter, which may perform more sophisticated
processing, e.g. statistical processing or plotting.
Options are used to list some of the formats supported by ffprobe or
for specifying which information to display, and for setting how
ffprobe will show it.
ffprobe output is designed to be easily parsable by a textual filter,
and consists of one or more sections of a form defined by the selected
writer, which is specified by the print_format option.
Sections may contain other nested sections, and are identified by a
name (which may be shared by other sections), and an unique name. See
the output of sections.
Metadata tags stored in the container or in the streams are recognized
and printed in the corresponding "FORMAT", "STREAM" or "PROGRAM_STREAM"
section.
OPTIONS
All the numerical options, if not specified otherwise, accept a string
representing a number as input, which may be followed by one of the SI
unit prefixes, for example: 'K', 'M', or 'G'.
If 'i' is appended to the SI unit prefix, the complete prefix will be
interpreted as a unit prefix for binary multiplies, which are based on
powers of 1024 instead of powers of 1000. Appending 'B' to the SI unit
prefix multiplies the value by 8. This allows using, for example: 'KB',
'MiB', 'G' and 'B' as number suffixes.
Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing the
option name with "no". For example using "-nofoo" will set the boolean
option with name "foo" to false.
Stream specifiers
Some options are applied per-stream, e.g. bitrate or codec. Stream
specifiers are used to precisely specify which stream(s) a given option
belongs to.
A stream specifier is a string generally appended to the option name
and separated from it by a colon. E.g. "-codec:a:1 ac3" contains the
"a:1" stream specifier, which matches the second audio stream.
Therefore, it would select the ac3 codec for the second audio stream.
A stream specifier can match several streams, so that the option is
applied to all of them. E.g. the stream specifier in "-b:a 128k"
matches all audio streams.
An empty stream specifier matches all streams. For example, "-codec
copy" or "-codec: copy" would copy all the streams without reencoding.
Possible forms of stream specifiers are:
stream_index
Matches the stream with this index. E.g. "-threads:1 4" would set
the thread count for the second stream to 4.
stream_type[:stream_index]
stream_type is one of following: 'v' for video, 'a' for audio, 's'
for subtitle, 'd' for data, and 't' for attachments. If
stream_index is given, then it matches stream number stream_index
of this type. Otherwise, it matches all streams of this type.
p:program_id[:stream_index]
If stream_index is given, then it matches the stream with number
stream_index in the program with the id program_id. Otherwise, it
matches all streams in the program.
#stream_id
Matches the stream by a format-specific ID.
Generic options
These options are shared amongst the ff* tools.
-L Show license.
-h, -?, -help, --help [arg]
Show help. An optional parameter may be specified to print help
about a specific item. If no argument is specified, only basic (non
advanced) tool options are shown.
Possible values of arg are:
long
Print advanced tool options in addition to the basic tool
options.
full
Print complete list of options, including shared and private
options for encoders, decoders, demuxers, muxers, filters, etc.
decoder=decoder_name
Print detailed information about the decoder named
decoder_name. Use the -decoders option to get a list of all
decoders.
encoder=encoder_name
Print detailed information about the encoder named
encoder_name. Use the -encoders option to get a list of all
encoders.
demuxer=demuxer_name
Print detailed information about the demuxer named
demuxer_name. Use the -formats option to get a list of all
demuxers and muxers.
muxer=muxer_name
Print detailed information about the muxer named muxer_name.
Use the -formats option to get a list of all muxers and
demuxers.
filter=filter_name
Print detailed information about the filter name filter_name.
Use the -filters option to get a list of all filters.
-version
Show version.
-formats
Show available formats.
-codecs
Show all codecs known to libavcodec.
Note that the term 'codec' is used throughout this documentation as
a shortcut for what is more correctly called a media bitstream
format.
-decoders
Show available decoders.
-encoders
Show all available encoders.
-bsfs
Show available bitstream filters.
-protocols
Show available protocols.
-filters
Show available libavfilter filters.
-pix_fmts
Show available pixel formats.
-sample_fmts
Show available sample formats.
-layouts
Show channel names and standard channel layouts.
-colors
Show recognized color names.
-loglevel [repeat+]loglevel | -v [repeat+]loglevel
Set the logging level used by the library. Adding "repeat+"
indicates that repeated log output should not be compressed to the
first line and the "Last message repeated n times" line will be
omitted. "repeat" can also be used alone. If "repeat" is used
alone, and with no prior loglevel set, the default loglevel will be
used. If multiple loglevel parameters are given, using 'repeat'
will not change the loglevel. loglevel is a number or a string
containing one of the following values:
quiet
Show nothing at all; be silent.
panic
Only show fatal errors which could lead the process to crash,
such as and assert failure. This is not currently used for
anything.
fatal
Only show fatal errors. These are errors after which the
process absolutely cannot continue after.
error
Show all errors, including ones which can be recovered from.
warning
Show all warnings and errors. Any message related to possibly
incorrect or unexpected events will be shown.
info
Show informative messages during processing. This is in
addition to warnings and errors. This is the default value.
verbose
Same as "info", except more verbose.
debug
Show everything, including debugging information.
By default the program logs to stderr, if coloring is supported by
the terminal, colors are used to mark errors and warnings. Log
coloring can be disabled setting the environment variable
AV_LOG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting the
environment variable AV_LOG_FORCE_COLOR. The use of the
environment variable NO_COLOR is deprecated and will be dropped in
a following FFmpeg version.
-report
Dump full command line and console output to a file named
"program-YYYYMMDD-HHMMSS.log" in the current directory. This file
can be useful for bug reports. It also implies "-loglevel
verbose".
Setting the environment variable "FFREPORT" to any value has the
same effect. If the value is a ':'-separated key=value sequence,
these options will affect the report; options values must be
escaped if they contain special characters or the options delimiter
':' (see the ``Quoting and escaping'' section in the ffmpeg-utils
manual). The following option is recognized:
file
set the file name to use for the report; %p is expanded to the
name of the program, %t is expanded to a timestamp, "%%" is
expanded to a plain "%"
Errors in parsing the environment variable are not fatal, and will
not appear in the report.
-hide_banner
Suppress printing banner.
All FFmpeg tools will normally show a copyright notice, build
options and library versions. This option can be used to suppress
printing this information.
-cpuflags flags (global)
Allows setting and clearing cpu flags. This option is intended for
testing. Do not use it unless you know what you're doing.
ffmpeg -cpuflags -sse+mmx ...
ffmpeg -cpuflags mmx ...
ffmpeg -cpuflags 0 ...
Possible flags for this option are:
x86
mmx
mmxext
sse
sse2
sse2slow
sse3
sse3slow
ssse3
atom
sse4.1
sse4.2
avx
xop
fma4
3dnow
3dnowext
cmov
ARM
armv5te
armv6
armv6t2
vfp
vfpv3
neon
PowerPC
altivec
Specific Processors
pentium2
pentium3
pentium4
k6
k62
athlon
athlonxp
k8
-opencl_bench
Benchmark all available OpenCL devices and show the results. This
option is only available when FFmpeg has been compiled with
"--enable-opencl".
-opencl_options options (global)
Set OpenCL environment options. This option is only available when
FFmpeg has been compiled with "--enable-opencl".
options must be a list of key=value option pairs separated by ':'.
See the ``OpenCL Options'' section in the ffmpeg-utils manual for
the list of supported options.
AVOptions
These options are provided directly by the libavformat, libavdevice and
libavcodec libraries. To see the list of available AVOptions, use the
-help option. They are separated into two categories:
generic
These options can be set for any container, codec or device.
Generic options are listed under AVFormatContext options for
containers/devices and under AVCodecContext options for codecs.
private
These options are specific to the given container, device or codec.
Private options are listed under their corresponding
containers/devices/codecs.
For example to write an ID3v2.3 header instead of a default ID3v2.4 to
an MP3 file, use the id3v2_version private option of the MP3 muxer:
ffmpeg -i input.flac -id3v2_version 3 out.mp3
All codec AVOptions are per-stream, and thus a stream specifier should
be attached to them.
Note: the -nooption syntax cannot be used for boolean AVOptions, use
-option 0/-option 1.
Note: the old undocumented way of specifying per-stream AVOptions by
prepending v/a/s to the options name is now obsolete and will be
removed soon.
Main options
-f format
Force format to use.
-unit
Show the unit of the displayed values.
-prefix
Use SI prefixes for the displayed values. Unless the
"-byte_binary_prefix" option is used all the prefixes are decimal.
-byte_binary_prefix
Force the use of binary prefixes for byte values.
-sexagesimal
Use sexagesimal format HH:MM:SS.MICROSECONDS for time values.
-pretty
Prettify the format of the displayed values, it corresponds to the
options "-unit -prefix -byte_binary_prefix -sexagesimal".
-of, -print_format writer_name[=writer_options]
Set the output printing format.
writer_name specifies the name of the writer, and writer_options
specifies the options to be passed to the writer.
For example for printing the output in JSON format, specify:
-print_format json
For more details on the available output printing formats, see the
Writers section below.
-sections
Print sections structure and section information, and exit. The
output is not meant to be parsed by a machine.
-select_streams stream_specifier
Select only the streams specified by stream_specifier. This option
affects only the options related to streams (e.g. "show_streams",
"show_packets", etc.).
For example to show only audio streams, you can use the command:
ffprobe -show_streams -select_streams a INPUT
To show only video packets belonging to the video stream with index
1:
ffprobe -show_packets -select_streams v:1 INPUT
-show_data
Show payload data, as a hexadecimal and ASCII dump. Coupled with
-show_packets, it will dump the packets' data. Coupled with
-show_streams, it will dump the codec extradata.
The dump is printed as the "data" field. It may contain newlines.
-show_error
Show information about the error found when trying to probe the
input.
The error information is printed within a section with name
"ERROR".
-show_format
Show information about the container format of the input multimedia
stream.
All the container format information is printed within a section
with name "FORMAT".
-show_format_entry name
Like -show_format, but only prints the specified entry of the
container format information, rather than all. This option may be
given more than once, then all specified entries will be shown.
This option is deprecated, use "show_entries" instead.
-show_entries section_entries
Set list of entries to show.
Entries are specified according to the following syntax.
section_entries contains a list of section entries separated by
":". Each section entry is composed by a section name (or unique
name), optionally followed by a list of entries local to that
section, separated by ",".
If section name is specified but is followed by no "=", all entries
are printed to output, together with all the contained sections.
Otherwise only the entries specified in the local section entries
list are printed. In particular, if "=" is specified but the list
of local entries is empty, then no entries will be shown for that
section.
Note that the order of specification of the local section entries
is not honored in the output, and the usual display order will be
retained.
The formal syntax is given by:
<LOCAL_SECTION_ENTRIES> ::= <SECTION_ENTRY_NAME>[,<LOCAL_SECTION_ENTRIES>]
<SECTION_ENTRY> ::= <SECTION_NAME>[=[<LOCAL_SECTION_ENTRIES>]]
<SECTION_ENTRIES> ::= <SECTION_ENTRY>[:<SECTION_ENTRIES>]
For example, to show only the index and type of each stream, and
the PTS time, duration time, and stream index of the packets, you
can specify the argument:
packet=pts_time,duration_time,stream_index : stream=index,codec_type
To show all the entries in the section "format", but only the codec
type in the section "stream", specify the argument:
format : stream=codec_type
To show all the tags in the stream and format sections:
format_tags : format_tags
To show only the "title" tag (if available) in the stream sections:
stream_tags=title
-show_packets
Show information about each packet contained in the input
multimedia stream.
The information for each single packet is printed within a
dedicated section with name "PACKET".
-show_frames
Show information about each frame and subtitle contained in the
input multimedia stream.
The information for each single frame is printed within a dedicated
section with name "FRAME" or "SUBTITLE".
-show_streams
Show information about each media stream contained in the input
multimedia stream.
Each media stream information is printed within a dedicated section
with name "STREAM".
-show_programs
Show information about programs and their streams contained in the
input multimedia stream.
Each media stream information is printed within a dedicated section
with name "PROGRAM_STREAM".
-show_chapters
Show information about chapters stored in the format.
Each chapter is printed within a dedicated section with name
"CHAPTER".
-count_frames
Count the number of frames per stream and report it in the
corresponding stream section.
-count_packets
Count the number of packets per stream and report it in the
corresponding stream section.
-read_intervals read_intervals
Read only the specified intervals. read_intervals must be a
sequence of interval specifications separated by ",". ffprobe will
seek to the interval starting point, and will continue reading from
that.
Each interval is specified by two optional parts, separated by "%".
The first part specifies the interval start position. It is
interpreted as an abolute position, or as a relative offset from
the current position if it is preceded by the "+" character. If
this first part is not specified, no seeking will be performed when
reading this interval.
The second part specifies the interval end position. It is
interpreted as an absolute position, or as a relative offset from
the current position if it is preceded by the "+" character. If the
offset specification starts with "#", it is interpreted as the
number of packets to read (not including the flushing packets) from
the interval start. If no second part is specified, the program
will read until the end of the input.
Note that seeking is not accurate, thus the actual interval start
point may be different from the specified position. Also, when an
interval duration is specified, the absolute end time will be
computed by adding the duration to the interval start point found
by seeking the file, rather than to the specified start value.
The formal syntax is given by:
<INTERVAL> ::= [<START>|+<START_OFFSET>][%[<END>|+<END_OFFSET>]]
<INTERVALS> ::= <INTERVAL>[,<INTERVALS>]
A few examples follow.
· Seek to time 10, read packets until 20 seconds after the found
seek point, then seek to position "01:30" (1 minute and thirty
seconds) and read packets until position "01:45".
10%+20,01:30%01:45
· Read only 42 packets after seeking to position "01:23":
01:23%+#42
· Read only the first 20 seconds from the start:
%+20
· Read from the start until position "02:30":
%02:30
-show_private_data, -private
Show private data, that is data depending on the format of the
particular shown element. This option is enabled by default, but
you may need to disable it for specific uses, for example when
creating XSD-compliant XML output.
-show_program_version
Show information related to program version.
Version information is printed within a section with name
"PROGRAM_VERSION".
-show_library_versions
Show information related to library versions.
Version information for each library is printed within a section
with name "LIBRARY_VERSION".
-show_versions
Show information related to program and library versions. This is
the equivalent of setting both -show_program_version and
-show_library_versions options.
-bitexact
Force bitexact output, useful to produce output which is not
dependent on the specific build.
-i input_file
Read input_file.
WRITERS
A writer defines the output format adopted by ffprobe, and will be used
for printing all the parts of the output.
A writer may accept one or more arguments, which specify the options to
adopt. The options are specified as a list of key=value pairs,
separated by ":".
All writers support the following options:
string_validation, sv
Set string validation mode.
The following values are accepted.
fail
The writer will fail immediately in case an invalid string
(UTF-8) sequence or code point is found in the input. This is
especially useful to validate input metadata.
ignore
Any validation error will be ignored. This will result in
possibly broken output, especially with the json or xml writer.
replace
The writer will substitute invalid UTF-8 sequences or code
points with the string specified with the
string_validation_replacement.
Default value is replace.
string_validation_replacement, svr
Set replacement string to use in case string_validation is set to
replace.
In case the option is not specified, the writer will assume the
empty string, that is it will remove the invalid sequences from the
input strings.
A description of the currently available writers follows.
default
Default format.
Print each section in the form:
[SECTION]
key1=val1
...
keyN=valN
[/SECTION]
Metadata tags are printed as a line in the corresponding FORMAT, STREAM
or PROGRAM_STREAM section, and are prefixed by the string "TAG:".
A description of the accepted options follows.
nokey, nk
If set to 1 specify not to print the key of each field. Default
value is 0.
noprint_wrappers, nw
If set to 1 specify not to print the section header and footer.
Default value is 0.
compact, csv
Compact and CSV format.
The "csv" writer is equivalent to "compact", but supports different
defaults.
Each section is printed on a single line. If no option is specifid,
the output has the form:
section|key1=val1| ... |keyN=valN
Metadata tags are printed in the corresponding "format" or "stream"
section. A metadata tag key, if printed, is prefixed by the string
"tag:".
The description of the accepted options follows.
item_sep, s
Specify the character to use for separating fields in the output
line. It must be a single printable character, it is "|" by
default ("," for the "csv" writer).
nokey, nk
If set to 1 specify not to print the key of each field. Its default
value is 0 (1 for the "csv" writer).
escape, e
Set the escape mode to use, default to "c" ("csv" for the "csv"
writer).
It can assume one of the following values:
c Perform C-like escaping. Strings containing a newline ('\n'),
carriage return ('\r'), a tab ('\t'), a form feed ('\f'), the
escaping character ('\') or the item separator character SEP
are escaped using C-like fashioned escaping, so that a newline
is converted to the sequence "\n", a carriage return to "\r",
'\' to "\\" and the separator SEP is converted to "\SEP".
csv Perform CSV-like escaping, as described in RFC4180. Strings
containing a newline ('\n'), a carriage return ('\r'), a double
quote ('"'), or SEP are enclosed in double-quotes.
none
Perform no escaping.
print_section, p
Print the section name at the begin of each line if the value is 1,
disable it with value set to 0. Default value is 1.
flat
Flat format.
A free-form output where each line contains an explicit key=value, such
as "streams.stream.3.tags.foo=bar". The output is shell escaped, so it
can be directly embedded in sh scripts as long as the separator
character is an alphanumeric character or an underscore (see sep_char
option).
The description of the accepted options follows.
sep_char, s
Separator character used to separate the chapter, the section name,
IDs and potential tags in the printed field key.
Default value is '.'.
hierarchical, h
Specify if the section name specification should be hierarchical.
If set to 1, and if there is more than one section in the current
chapter, the section name will be prefixed by the name of the
chapter. A value of 0 will disable this behavior.
Default value is 1.
ini
INI format output.
Print output in an INI based format.
The following conventions are adopted:
· all key and values are UTF-8
· '.' is the subgroup separator
· newline, '\t', '\f', '\b' and the following characters are escaped
· '\' is the escape character
· '#' is the comment indicator
· '=' is the key/value separator
· ':' is not used but usually parsed as key/value separator
This writer accepts options as a list of key=value pairs, separated by
":".
The description of the accepted options follows.
hierarchical, h
Specify if the section name specification should be hierarchical.
If set to 1, and if there is more than one section in the current
chapter, the section name will be prefixed by the name of the
chapter. A value of 0 will disable this behavior.
Default value is 1.
json
JSON based format.
Each section is printed using JSON notation.
The description of the accepted options follows.
compact, c
If set to 1 enable compact output, that is each section will be
printed on a single line. Default value is 0.
For more information about JSON, see <http://www.json.org/>.
xml
XML based format.
The XML output is described in the XML schema description file
ffprobe.xsd installed in the FFmpeg datadir.
An updated version of the schema can be retrieved at the url
<http://www.ffmpeg.org/schema/ffprobe.xsd>, which redirects to the
latest schema committed into the FFmpeg development source code tree.
Note that the output issued will be compliant to the ffprobe.xsd schema
only when no special global output options (unit, prefix,
byte_binary_prefix, sexagesimal etc.) are specified.
The description of the accepted options follows.
fully_qualified, q
If set to 1 specify if the output should be fully qualified.
Default value is 0. This is required for generating an XML file
which can be validated through an XSD file.
xsd_compliant, x
If set to 1 perform more checks for ensuring that the output is XSD
compliant. Default value is 0. This option automatically sets
fully_qualified to 1.
For more information about the XML format, see
<http://www.w3.org/XML/>.
TIMECODE
ffprobe supports Timecode extraction:
· MPEG1/2 timecode is extracted from the GOP, and is available in the
video stream details (-show_streams, see timecode).
· MOV timecode is extracted from tmcd track, so is available in the
tmcd stream metadata (-show_streams, see TAG:timecode).
· DV, GXF and AVI timecodes are available in format metadata
(-show_format, see TAG:timecode).
SYNTAX
This section documents the syntax and formats employed by the FFmpeg
libraries and tools.
Quoting and escaping
FFmpeg adopts the following quoting and escaping mechanism, unless
explicitly specified. The following rules are applied:
· "'" and "\" are special characters (respectively used for quoting
and escaping). In addition to them, there might be other special
characters depending on the specific syntax where the escaping and
quoting are employed.
· A special character is escaped by prefixing it with a '\'.
· All characters enclosed between '' are included literally in the
parsed string. The quote character "'" itself cannot be quoted, so
you may need to close the quote and escape it.
· Leading and trailing whitespaces, unless escaped or quoted, are
removed from the parsed string.
Note that you may need to add a second level of escaping when using the
command line or a script, which depends on the syntax of the adopted
shell language.
The function "av_get_token" defined in libavutil/avstring.h can be used
to parse a token quoted or escaped according to the rules defined
above.
The tool tools/ffescape in the FFmpeg source tree can be used to
automatically quote or escape a string in a script.
Examples
· Escape the string "Crime d'Amour" containing the "'" special
character:
Crime d\'Amour
· The string above contains a quote, so the "'" needs to be escaped
when quoting it:
'Crime d'\''Amour'
· Include leading or trailing whitespaces using quoting:
' this string starts and ends with whitespaces '
· Escaping and quoting can be mixed together:
' The string '\'string\'' is a string '
· To include a literal "\" you can use either escaping or quoting:
'c:\foo' can be written as c:\\foo
Date
The accepted syntax is:
[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z]
now
If the value is "now" it takes the current time.
Time is local time unless Z is appended, in which case it is
interpreted as UTC. If the year-month-day part is not specified it
takes the current year-month-day.
Time duration
There are two accepted syntaxes for expressing time duration.
[-][<HH>:]<MM>:<SS>[.<m>...]
HH expresses the number of hours, MM the number of minutes for a
maximum of 2 digits, and SS the number of seconds for a maximum of 2
digits. The m at the end expresses decimal value for SS.
or
[-]<S>+[.<m>...]
S expresses the number of seconds, with the optional decimal part m.
In both expressions, the optional - indicates negative duration.
Examples
The following examples are all valid time duration:
55 55 seconds
12:03:45
12 hours, 03 minutes and 45 seconds
23.189
23.189 seconds
Video size
Specify the size of the sourced video, it may be a string of the form
widthxheight, or the name of a size abbreviation.
The following abbreviations are recognized:
ntsc
720x480
pal 720x576
qntsc
352x240
qpal
352x288
sntsc
640x480
spal
768x576
film
352x240
ntsc-film
352x240
sqcif
128x96
qcif
176x144
cif 352x288
4cif
704x576
16cif
1408x1152
qqvga
160x120
qvga
320x240
vga 640x480
svga
800x600
xga 1024x768
uxga
1600x1200
qxga
2048x1536
sxga
1280x1024
qsxga
2560x2048
hsxga
5120x4096
wvga
852x480
wxga
1366x768
wsxga
1600x1024
wuxga
1920x1200
woxga
2560x1600
wqsxga
3200x2048
wquxga
3840x2400
whsxga
6400x4096
whuxga
7680x4800
cga 320x200
ega 640x350
hd480
852x480
hd720
1280x720
hd1080
1920x1080
2k 2048x1080
2kflat
1998x1080
2kscope
2048x858
4k 4096x2160
4kflat
3996x2160
4kscope
4096x1716
nhd 640x360
hqvga
240x160
wqvga
400x240
fwqvga
432x240
hvga
480x320
qhd 960x540
Video rate
Specify the frame rate of a video, expressed as the number of frames
generated per second. It has to be a string in the format
frame_rate_num/frame_rate_den, an integer number, a float number or a
valid video frame rate abbreviation.
The following abbreviations are recognized:
ntsc
30000/1001
pal 25/1
qntsc
30000/1001
qpal
25/1
sntsc
30000/1001
spal
25/1
film
24/1
ntsc-film
24000/1001
Ratio
A ratio can be expressed as an expression, or in the form
numerator:denominator.
Note that a ratio with infinite (1/0) or negative value is considered
valid, so you should check on the returned value if you want to exclude
those values.
The undefined value can be expressed using the "0:0" string.
Color
It can be the name of a color as defined below (case insensitive match)
or a "[0x|#]RRGGBB[AA]" sequence, possibly followed by @ and a string
representing the alpha component.
The alpha component may be a string composed by "0x" followed by an
hexadecimal number or a decimal number between 0.0 and 1.0, which
represents the opacity value (0x00 or 0.0 means completely transparent,
0xff or 1.0 completely opaque). If the alpha component is not specified
then 0xff is assumed.
The string random will result in a random color.
The following names of colors are recognized:
AliceBlue
0xF0F8FF
AntiqueWhite
0xFAEBD7
Aqua
0x00FFFF
Aquamarine
0x7FFFD4
Azure
0xF0FFFF
Beige
0xF5F5DC
Bisque
0xFFE4C4
Black
0x000000
BlanchedAlmond
0xFFEBCD
Blue
0x0000FF
BlueViolet
0x8A2BE2
Brown
0xA52A2A
BurlyWood
0xDEB887
CadetBlue
0x5F9EA0
Chartreuse
0x7FFF00
Chocolate
0xD2691E
Coral
0xFF7F50
CornflowerBlue
0x6495ED
Cornsilk
0xFFF8DC
Crimson
0xDC143C
Cyan
0x00FFFF
DarkBlue
0x00008B
DarkCyan
0x008B8B
DarkGoldenRod
0xB8860B
DarkGray
0xA9A9A9
DarkGreen
0x006400
DarkKhaki
0xBDB76B
DarkMagenta
0x8B008B
DarkOliveGreen
0x556B2F
Darkorange
0xFF8C00
DarkOrchid
0x9932CC
DarkRed
0x8B0000
DarkSalmon
0xE9967A
DarkSeaGreen
0x8FBC8F
DarkSlateBlue
0x483D8B
DarkSlateGray
0x2F4F4F
DarkTurquoise
0x00CED1
DarkViolet
0x9400D3
DeepPink
0xFF1493
DeepSkyBlue
0x00BFFF
DimGray
0x696969
DodgerBlue
0x1E90FF
FireBrick
0xB22222
FloralWhite
0xFFFAF0
ForestGreen
0x228B22
Fuchsia
0xFF00FF
Gainsboro
0xDCDCDC
GhostWhite
0xF8F8FF
Gold
0xFFD700
GoldenRod
0xDAA520
Gray
0x808080
Green
0x008000
GreenYellow
0xADFF2F
HoneyDew
0xF0FFF0
HotPink
0xFF69B4
IndianRed
0xCD5C5C
Indigo
0x4B0082
Ivory
0xFFFFF0
Khaki
0xF0E68C
Lavender
0xE6E6FA
LavenderBlush
0xFFF0F5
LawnGreen
0x7CFC00
LemonChiffon
0xFFFACD
LightBlue
0xADD8E6
LightCoral
0xF08080
LightCyan
0xE0FFFF
LightGoldenRodYellow
0xFAFAD2
LightGreen
0x90EE90
LightGrey
0xD3D3D3
LightPink
0xFFB6C1
LightSalmon
0xFFA07A
LightSeaGreen
0x20B2AA
LightSkyBlue
0x87CEFA
LightSlateGray
0x778899
LightSteelBlue
0xB0C4DE
LightYellow
0xFFFFE0
Lime
0x00FF00
LimeGreen
0x32CD32
Linen
0xFAF0E6
Magenta
0xFF00FF
Maroon
0x800000
MediumAquaMarine
0x66CDAA
MediumBlue
0x0000CD
MediumOrchid
0xBA55D3
MediumPurple
0x9370D8
MediumSeaGreen
0x3CB371
MediumSlateBlue
0x7B68EE
MediumSpringGreen
0x00FA9A
MediumTurquoise
0x48D1CC
MediumVioletRed
0xC71585
MidnightBlue
0x191970
MintCream
0xF5FFFA
MistyRose
0xFFE4E1
Moccasin
0xFFE4B5
NavajoWhite
0xFFDEAD
Navy
0x000080
OldLace
0xFDF5E6
Olive
0x808000
OliveDrab
0x6B8E23
Orange
0xFFA500
OrangeRed
0xFF4500
Orchid
0xDA70D6
PaleGoldenRod
0xEEE8AA
PaleGreen
0x98FB98
PaleTurquoise
0xAFEEEE
PaleVioletRed
0xD87093
PapayaWhip
0xFFEFD5
PeachPuff
0xFFDAB9
Peru
0xCD853F
Pink
0xFFC0CB
Plum
0xDDA0DD
PowderBlue
0xB0E0E6
Purple
0x800080
Red 0xFF0000
RosyBrown
0xBC8F8F
RoyalBlue
0x4169E1
SaddleBrown
0x8B4513
Salmon
0xFA8072
SandyBrown
0xF4A460
SeaGreen
0x2E8B57
SeaShell
0xFFF5EE
Sienna
0xA0522D
Silver
0xC0C0C0
SkyBlue
0x87CEEB
SlateBlue
0x6A5ACD
SlateGray
0x708090
Snow
0xFFFAFA
SpringGreen
0x00FF7F
SteelBlue
0x4682B4
Tan 0xD2B48C
Teal
0x008080
Thistle
0xD8BFD8
Tomato
0xFF6347
Turquoise
0x40E0D0
Violet
0xEE82EE
Wheat
0xF5DEB3
White
0xFFFFFF
WhiteSmoke
0xF5F5F5
Yellow
0xFFFF00
YellowGreen
0x9ACD32
Channel Layout
A channel layout specifies the spatial disposition of the channels in a
multi-channel audio stream. To specify a channel layout, FFmpeg makes
use of a special syntax.
Individual channels are identified by an id, as given by the table
below:
FL front left
FR front right
FC front center
LFE low frequency
BL back left
BR back right
FLC front left-of-center
FRC front right-of-center
BC back center
SL side left
SR side right
TC top center
TFL top front left
TFC top front center
TFR top front right
TBL top back left
TBC top back center
TBR top back right
DL downmix left
DR downmix right
WL wide left
WR wide right
SDL surround direct left
SDR surround direct right
LFE2
low frequency 2
Standard channel layout compositions can be specified by using the
following identifiers:
mono
FC
stereo
FL+FR
2.1 FL+FR+LFE
3.0 FL+FR+FC
3.0(back)
FL+FR+BC
4.0 FL+FR+FC+BC
quad
FL+FR+BL+BR
quad(side)
FL+FR+SL+SR
3.1 FL+FR+FC+LFE
5.0 FL+FR+FC+BL+BR
5.0(side)
FL+FR+FC+SL+SR
4.1 FL+FR+FC+LFE+BC
5.1 FL+FR+FC+LFE+BL+BR
5.1(side)
FL+FR+FC+LFE+SL+SR
6.0 FL+FR+FC+BC+SL+SR
6.0(front)
FL+FR+FLC+FRC+SL+SR
hexagonal
FL+FR+FC+BL+BR+BC
6.1 FL+FR+FC+LFE+BC+SL+SR
6.1 FL+FR+FC+LFE+BL+BR+BC
6.1(front)
FL+FR+LFE+FLC+FRC+SL+SR
7.0 FL+FR+FC+BL+BR+SL+SR
7.0(front)
FL+FR+FC+FLC+FRC+SL+SR
7.1 FL+FR+FC+LFE+BL+BR+SL+SR
7.1(wide)
FL+FR+FC+LFE+BL+BR+FLC+FRC
7.1(wide-side)
FL+FR+FC+LFE+FLC+FRC+SL+SR
octagonal
FL+FR+FC+BL+BR+BC+SL+SR
downmix
DL+DR
A custom channel layout can be specified as a sequence of terms,
separated by '+' or '|'. Each term can be:
· the name of a standard channel layout (e.g. mono, stereo, 4.0,
quad, 5.0, etc.)
· the name of a single channel (e.g. FL, FR, FC, LFE, etc.)
· a number of channels, in decimal, optionally followed by 'c',
yielding the default channel layout for that number of channels
(see the function "av_get_default_channel_layout")
· a channel layout mask, in hexadecimal starting with "0x" (see the
"AV_CH_*" macros in libavutil/channel_layout.h.
Starting from libavutil version 53 the trailing character "c" to
specify a number of channels will be required, while a channel layout
mask could also be specified as a decimal number (if and only if not
followed by "c").
See also the function "av_get_channel_layout" defined in
libavutil/channel_layout.h.
EXPRESSION EVALUATION
When evaluating an arithmetic expression, FFmpeg uses an internal
formula evaluator, implemented through the libavutil/eval.h interface.
An expression may contain unary, binary operators, constants, and
functions.
Two expressions expr1 and expr2 can be combined to form another
expression "expr1;expr2". expr1 and expr2 are evaluated in turn, and
the new expression evaluates to the value of expr2.
The following binary operators are available: "+", "-", "*", "/", "^".
The following unary operators are available: "+", "-".
The following functions are available:
abs(x)
Compute absolute value of x.
acos(x)
Compute arccosine of x.
asin(x)
Compute arcsine of x.
atan(x)
Compute arctangent of x.
between(x, min, max)
Return 1 if x is greater than or equal to min and lesser than or
equal to max, 0 otherwise.
bitand(x, y)
bitor(x, y)
Compute bitwise and/or operation on x and y.
The results of the evaluation of x and y are converted to integers
before executing the bitwise operation.
Note that both the conversion to integer and the conversion back to
floating point can lose precision. Beware of unexpected results for
large numbers (usually 2^53 and larger).
ceil(expr)
Round the value of expression expr upwards to the nearest integer.
For example, "ceil(1.5)" is "2.0".
cos(x)
Compute cosine of x.
cosh(x)
Compute hyperbolic cosine of x.
eq(x, y)
Return 1 if x and y are equivalent, 0 otherwise.
exp(x)
Compute exponential of x (with base "e", the Euler's number).
floor(expr)
Round the value of expression expr downwards to the nearest
integer. For example, "floor(-1.5)" is "-2.0".
gauss(x)
Compute Gauss function of x, corresponding to "exp(-x*x/2) /
sqrt(2*PI)".
gcd(x, y)
Return the greatest common divisor of x and y. If both x and y are
0 or either or both are less than zero then behavior is undefined.
gt(x, y)
Return 1 if x is greater than y, 0 otherwise.
gte(x, y)
Return 1 if x is greater than or equal to y, 0 otherwise.
hypot(x, y)
This function is similar to the C function with the same name; it
returns "sqrt(x*x + y*y)", the length of the hypotenuse of a right
triangle with sides of length x and y, or the distance of the point
(x, y) from the origin.
if(x, y)
Evaluate x, and if the result is non-zero return the result of the
evaluation of y, return 0 otherwise.
if(x, y, z)
Evaluate x, and if the result is non-zero return the evaluation
result of y, otherwise the evaluation result of z.
ifnot(x, y)
Evaluate x, and if the result is zero return the result of the
evaluation of y, return 0 otherwise.
ifnot(x, y, z)
Evaluate x, and if the result is zero return the evaluation result
of y, otherwise the evaluation result of z.
isinf(x)
Return 1.0 if x is +/-INFINITY, 0.0 otherwise.
isnan(x)
Return 1.0 if x is NAN, 0.0 otherwise.
ld(var)
Allow to load the value of the internal variable with number var,
which was previously stored with st(var, expr). The function
returns the loaded value.
log(x)
Compute natural logarithm of x.
lt(x, y)
Return 1 if x is lesser than y, 0 otherwise.
lte(x, y)
Return 1 if x is lesser than or equal to y, 0 otherwise.
max(x, y)
Return the maximum between x and y.
min(x, y)
Return the maximum between x and y.
mod(x, y)
Compute the remainder of division of x by y.
not(expr)
Return 1.0 if expr is zero, 0.0 otherwise.
pow(x, y)
Compute the power of x elevated y, it is equivalent to "(x)^(y)".
print(t)
print(t, l)
Print the value of expression t with loglevel l. If l is not
specified then a default log level is used. Returns the value of
the expression printed.
Prints t with loglevel l
random(x)
Return a pseudo random value between 0.0 and 1.0. x is the index of
the internal variable which will be used to save the seed/state.
root(expr, max)
Find an input value for which the function represented by expr with
argument ld(0) is 0 in the interval 0..max.
The expression in expr must denote a continuous function or the
result is undefined.
ld(0) is used to represent the function input value, which means
that the given expression will be evaluated multiple times with
various input values that the expression can access through ld(0).
When the expression evaluates to 0 then the corresponding input
value will be returned.
sin(x)
Compute sine of x.
sinh(x)
Compute hyperbolic sine of x.
sqrt(expr)
Compute the square root of expr. This is equivalent to "(expr)^.5".
squish(x)
Compute expression "1/(1 + exp(4*x))".
st(var, expr)
Allow to store the value of the expression expr in an internal
variable. var specifies the number of the variable where to store
the value, and it is a value ranging from 0 to 9. The function
returns the value stored in the internal variable. Note, Variables
are currently not shared between expressions.
tan(x)
Compute tangent of x.
tanh(x)
Compute hyperbolic tangent of x.
taylor(expr, x)
taylor(expr, x, id)
Evaluate a Taylor series at x, given an expression representing the
"ld(id)"-th derivative of a function at 0.
When the series does not converge the result is undefined.
ld(id) is used to represent the derivative order in expr, which
means that the given expression will be evaluated multiple times
with various input values that the expression can access through
"ld(id)". If id is not specified then 0 is assumed.
Note, when you have the derivatives at y instead of 0,
"taylor(expr, x-y)" can be used.
time(0)
Return the current (wallclock) time in seconds.
trunc(expr)
Round the value of expression expr towards zero to the nearest
integer. For example, "trunc(-1.5)" is "-1.0".
while(cond, expr)
Evaluate expression expr while the expression cond is non-zero, and
returns the value of the last expr evaluation, or NAN if cond was
always false.
The following constants are available:
PI area of the unit disc, approximately 3.14
E exp(1) (Euler's number), approximately 2.718
PHI golden ratio (1+sqrt(5))/2, approximately 1.618
Assuming that an expression is considered "true" if it has a non-zero
value, note that:
"*" works like AND
"+" works like OR
For example the construct:
if (A AND B) then C
is equivalent to:
if(A*B, C)
In your C code, you can extend the list of unary and binary functions,
and define recognized constants, so that they are available for your
expressions.
The evaluator also recognizes the International System unit prefixes.
If 'i' is appended after the prefix, binary prefixes are used, which
are based on powers of 1024 instead of powers of 1000. The 'B' postfix
multiplies the value by 8, and can be appended after a unit prefix or
used alone. This allows using for example 'KB', 'MiB', 'G' and 'B' as
number postfix.
The list of available International System prefixes follows, with
indication of the corresponding powers of 10 and of 2.
y 10^-24 / 2^-80
z 10^-21 / 2^-70
a 10^-18 / 2^-60
f 10^-15 / 2^-50
p 10^-12 / 2^-40
n 10^-9 / 2^-30
u 10^-6 / 2^-20
m 10^-3 / 2^-10
c 10^-2
d 10^-1
h 10^2
k 10^3 / 2^10
K 10^3 / 2^10
M 10^6 / 2^20
G 10^9 / 2^30
T 10^12 / 2^40
P 10^15 / 2^40
E 10^18 / 2^50
Z 10^21 / 2^60
Y 10^24 / 2^70
OPENCL OPTIONS
When FFmpeg is configured with "--enable-opencl", it is possible to set
the options for the global OpenCL context.
The list of supported options follows:
build_options
Set build options used to compile the registered kernels.
See reference "OpenCL Specification Version: 1.2 chapter 5.6.4".
platform_idx
Select the index of the platform to run OpenCL code.
The specified index must be one of the indexes in the device list
which can be obtained with "ffmpeg -opencl_bench" or
"av_opencl_get_device_list()".
device_idx
Select the index of the device used to run OpenCL code.
The specified index must be one of the indexes in the device list
which can be obtained with "ffmpeg -opencl_bench" or
"av_opencl_get_device_list()".
CODEC OPTIONS
libavcodec provides some generic global options, which can be set on
all the encoders and decoders. In addition each codec may support so-
called private options, which are specific for a given codec.
Sometimes, a global option may only affect a specific kind of codec,
and may be unsensical or ignored by another, so you need to be aware of
the meaning of the specified options. Also some options are meant only
for decoding or encoding.
Options may be set by specifying -option value in the FFmpeg tools, or
by setting the value explicitly in the "AVCodecContext" options or
using the libavutil/opt.h API for programmatic use.
The list of supported options follow:
b integer (encoding,audio,video)
Set bitrate in bits/s. Default value is 200K.
ab integer (encoding,audio)
Set audio bitrate (in bits/s). Default value is 128K.
bt integer (encoding,video)
Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate
tolerance specifies how far ratecontrol is willing to deviate from
the target average bitrate value. This is not related to min/max
bitrate. Lowering tolerance too much has an adverse effect on
quality.
flags flags (decoding/encoding,audio,video,subtitles)
Set generic flags.
Possible values:
mv4 Use four motion vector by macroblock (mpeg4).
qpel
Use 1/4 pel motion compensation.
loop
Use loop filter.
qscale
Use fixed qscale.
gmc Use gmc.
mv0 Always try a mb with mv=<0,0>.
input_preserved
pass1
Use internal 2pass ratecontrol in first pass mode.
pass2
Use internal 2pass ratecontrol in second pass mode.
gray
Only decode/encode grayscale.
emu_edge
Do not draw edges.
psnr
Set error[?] variables during encoding.
truncated
naq Normalize adaptive quantization.
ildct
Use interlaced DCT.
low_delay
Force low delay.
global_header
Place global headers in extradata instead of every keyframe.
bitexact
Use only bitexact stuff (except (I)DCT).
aic Apply H263 advanced intra coding / mpeg4 ac prediction.
cbp Deprecated, use mpegvideo private options instead.
qprd
Deprecated, use mpegvideo private options instead.
ilme
Apply interlaced motion estimation.
cgop
Use closed gop.
me_method integer (encoding,video)
Set motion estimation method.
Possible values:
zero
zero motion estimation (fastest)
full
full motion estimation (slowest)
epzs
EPZS motion estimation (default)
esa esa motion estimation (alias for full)
tesa
tesa motion estimation
dia dia motion estimation (alias for epzs)
log log motion estimation
phods
phods motion estimation
x1 X1 motion estimation
hex hex motion estimation
umh umh motion estimation
iter
iter motion estimation
extradata_size integer
Set extradata size.
time_base rational number
Set codec time base.
It is the fundamental unit of time (in seconds) in terms of which
frame timestamps are represented. For fixed-fps content, timebase
should be "1 / frame_rate" and timestamp increments should be
identically 1.
g integer (encoding,video)
Set the group of picture size. Default value is 12.
ar integer (decoding/encoding,audio)
Set audio sampling rate (in Hz).
ac integer (decoding/encoding,audio)
Set number of audio channels.
cutoff integer (encoding,audio)
Set cutoff bandwidth.
frame_size integer (encoding,audio)
Set audio frame size.
Each submitted frame except the last must contain exactly
frame_size samples per channel. May be 0 when the codec has
CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is
not restricted. It is set by some decoders to indicate constant
frame size.
frame_number integer
Set the frame number.
delay integer
qcomp float (encoding,video)
Set video quantizer scale compression (VBR). It is used as a
constant in the ratecontrol equation. Recommended range for default
rc_eq: 0.0-1.0.
qblur float (encoding,video)
Set video quantizer scale blur (VBR).
qmin integer (encoding,video)
Set min video quantizer scale (VBR). Must be included between -1
and 69, default value is 2.
qmax integer (encoding,video)
Set max video quantizer scale (VBR). Must be included between -1
and 1024, default value is 31.
qdiff integer (encoding,video)
Set max difference between the quantizer scale (VBR).
bf integer (encoding,video)
Set max number of B frames between non-B-frames.
Must be an integer between -1 and 16. 0 means that B-frames are
disabled. If a value of -1 is used, it will choose an automatic
value depending on the encoder.
Default value is 0.
b_qfactor float (encoding,video)
Set qp factor between P and B frames.
rc_strategy integer (encoding,video)
Set ratecontrol method.
b_strategy integer (encoding,video)
Set strategy to choose between I/P/B-frames.
ps integer (encoding,video)
Set RTP payload size in bytes.
mv_bits integer
header_bits integer
i_tex_bits integer
p_tex_bits integer
i_count integer
p_count integer
skip_count integer
misc_bits integer
frame_bits integer
codec_tag integer
bug flags (decoding,video)
Workaround not auto detected encoder bugs.
Possible values:
autodetect
old_msmpeg4
some old lavc generated msmpeg4v3 files (no autodetection)
xvid_ilace
Xvid interlacing bug (autodetected if fourcc==XVIX)
ump4
(autodetected if fourcc==UMP4)
no_padding
padding bug (autodetected)
amv
ac_vlc
illegal vlc bug (autodetected per fourcc)
qpel_chroma
std_qpel
old standard qpel (autodetected per fourcc/version)
qpel_chroma2
direct_blocksize
direct-qpel-blocksize bug (autodetected per fourcc/version)
edge
edge padding bug (autodetected per fourcc/version)
hpel_chroma
dc_clip
ms Workaround various bugs in microsoft broken decoders.
trunc
trancated frames
lelim integer (encoding,video)
Set single coefficient elimination threshold for luminance
(negative values also consider DC coefficient).
celim integer (encoding,video)
Set single coefficient elimination threshold for chrominance
(negative values also consider dc coefficient)
strict integer (decoding/encoding,audio,video)
Specify how strictly to follow the standards.
Possible values:
very
strictly conform to a older more strict version of the spec or
reference software
strict
strictly conform to all the things in the spec no matter what
consequences
normal
unofficial
allow unofficial extensions
experimental
allow non standardized experimental things, experimental
(unfinished/work in progress/not well tested) decoders and
encoders. Note: experimental decoders can pose a security
risk, do not use this for decoding untrusted input.
b_qoffset float (encoding,video)
Set QP offset between P and B frames.
err_detect flags (decoding,audio,video)
Set error detection flags.
Possible values:
crccheck
verify embedded CRCs
bitstream
detect bitstream specification deviations
buffer
detect improper bitstream length
explode
abort decoding on minor error detection
careful
consider things that violate the spec and have not been seen in
the wild as errors
compliant
consider all spec non compliancies as errors
aggressive
consider things that a sane encoder should not do as an error
has_b_frames integer
block_align integer
mpeg_quant integer (encoding,video)
Use MPEG quantizers instead of H.263.
qsquish float (encoding,video)
How to keep quantizer between qmin and qmax (0 = clip, 1 = use
differentiable function).
rc_qmod_amp float (encoding,video)
Set experimental quantizer modulation.
rc_qmod_freq integer (encoding,video)
Set experimental quantizer modulation.
rc_override_count integer
rc_eq string (encoding,video)
Set rate control equation. When computing the expression, besides
the standard functions defined in the section 'Expression
Evaluation', the following functions are available: bits2qp(bits),
qp2bits(qp). Also the following constants are available: iTex pTex
tex mv fCode iCount mcVar var isI isP isB avgQP qComp avgIITex
avgPITex avgPPTex avgBPTex avgTex.
maxrate integer (encoding,audio,video)
Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
minrate integer (encoding,audio,video)
Set min bitrate tolerance (in bits/s). Most useful in setting up a
CBR encode. It is of little use elsewise.
bufsize integer (encoding,audio,video)
Set ratecontrol buffer size (in bits).
rc_buf_aggressivity float (encoding,video)
Currently useless.
i_qfactor float (encoding,video)
Set QP factor between P and I frames.
i_qoffset float (encoding,video)
Set QP offset between P and I frames.
rc_init_cplx float (encoding,video)
Set initial complexity for 1-pass encoding.
dct integer (encoding,video)
Set DCT algorithm.
Possible values:
auto
autoselect a good one (default)
fastint
fast integer
int accurate integer
mmx
altivec
faan
floating point AAN DCT
lumi_mask float (encoding,video)
Compress bright areas stronger than medium ones.
tcplx_mask float (encoding,video)
Set temporal complexity masking.
scplx_mask float (encoding,video)
Set spatial complexity masking.
p_mask float (encoding,video)
Set inter masking.
dark_mask float (encoding,video)
Compress dark areas stronger than medium ones.
idct integer (decoding/encoding,video)
Select IDCT implementation.
Possible values:
auto
int
simple
simplemmx
arm
altivec
sh4
simplearm
simplearmv5te
simplearmv6
simpleneon
simplealpha
ipp
xvidmmx
faani
floating point AAN IDCT
slice_count integer
ec flags (decoding,video)
Set error concealment strategy.
Possible values:
guess_mvs
iterative motion vector (MV) search (slow)
deblock
use strong deblock filter for damaged MBs
bits_per_coded_sample integer
pred integer (encoding,video)
Set prediction method.
Possible values:
left
plane
median
aspect rational number (encoding,video)
Set sample aspect ratio.
debug flags (decoding/encoding,audio,video,subtitles)
Print specific debug info.
Possible values:
pict
picture info
rc rate control
bitstream
mb_type
macroblock (MB) type
qp per-block quantization parameter (QP)
mv motion vector
dct_coeff
skip
startcode
pts
er error recognition
mmco
memory management control operations (H.264)
bugs
vis_qp
visualize quantization parameter (QP), lower QP are tinted
greener
vis_mb_type
visualize block types
buffers
picture buffer allocations
thread_ops
threading operations
vismv integer (decoding,video)
Visualize motion vectors (MVs).
Possible values:
pf forward predicted MVs of P-frames
bf forward predicted MVs of B-frames
bb backward predicted MVs of B-frames
cmp integer (encoding,video)
Set full pel me compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd
sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr
sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero
0
vsad
sum of absolute vertical differences
vsse
sum of squared vertical differences
nsse
noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax
chroma
subcmp integer (encoding,video)
Set sub pel me compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd
sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr
sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero
0
vsad
sum of absolute vertical differences
vsse
sum of squared vertical differences
nsse
noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax
chroma
mbcmp integer (encoding,video)
Set macroblock compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd
sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr
sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero
0
vsad
sum of absolute vertical differences
vsse
sum of squared vertical differences
nsse
noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax
chroma
ildctcmp integer (encoding,video)
Set interlaced dct compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd
sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr
sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero
0
vsad
sum of absolute vertical differences
vsse
sum of squared vertical differences
nsse
noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax
chroma
dia_size integer (encoding,video)
Set diamond type & size for motion estimation.
last_pred integer (encoding,video)
Set amount of motion predictors from the previous frame.
preme integer (encoding,video)
Set pre motion estimation.
precmp integer (encoding,video)
Set pre motion estimation compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd
sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr
sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero
0
vsad
sum of absolute vertical differences
vsse
sum of squared vertical differences
nsse
noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax
chroma
pre_dia_size integer (encoding,video)
Set diamond type & size for motion estimation pre-pass.
subq integer (encoding,video)
Set sub pel motion estimation quality.
dtg_active_format integer
me_range integer (encoding,video)
Set limit motion vectors range (1023 for DivX player).
ibias integer (encoding,video)
Set intra quant bias.
pbias integer (encoding,video)
Set inter quant bias.
color_table_id integer
global_quality integer (encoding,audio,video)
coder integer (encoding,video)
Possible values:
vlc variable length coder / huffman coder
ac arithmetic coder
raw raw (no encoding)
rle run-length coder
deflate
deflate-based coder
context integer (encoding,video)
Set context model.
slice_flags integer
xvmc_acceleration integer
mbd integer (encoding,video)
Set macroblock decision algorithm (high quality mode).
Possible values:
simple
use mbcmp (default)
bits
use fewest bits
rd use best rate distortion
stream_codec_tag integer
sc_threshold integer (encoding,video)
Set scene change threshold.
lmin integer (encoding,video)
Set min lagrange factor (VBR).
lmax integer (encoding,video)
Set max lagrange factor (VBR).
nr integer (encoding,video)
Set noise reduction.
rc_init_occupancy integer (encoding,video)
Set number of bits which should be loaded into the rc buffer before
decoding starts.
flags2 flags (decoding/encoding,audio,video)
Possible values:
fast
Allow non spec compliant speedup tricks.
sgop
Deprecated, use mpegvideo private options instead.
noout
Skip bitstream encoding.
ignorecrop
Ignore cropping information from sps.
local_header
Place global headers at every keyframe instead of in extradata.
chunks
Frame data might be split into multiple chunks.
showall
Show all frames before the first keyframe.
skiprd
Deprecated, use mpegvideo private options instead.
error integer (encoding,video)
qns integer (encoding,video)
Deprecated, use mpegvideo private options instead.
threads integer (decoding/encoding,video)
Possible values:
auto
detect a good number of threads
me_threshold integer (encoding,video)
Set motion estimation threshold.
mb_threshold integer (encoding,video)
Set macroblock threshold.
dc integer (encoding,video)
Set intra_dc_precision.
nssew integer (encoding,video)
Set nsse weight.
skip_top integer (decoding,video)
Set number of macroblock rows at the top which are skipped.
skip_bottom integer (decoding,video)
Set number of macroblock rows at the bottom which are skipped.
profile integer (encoding,audio,video)
Possible values:
unknown
aac_main
aac_low
aac_ssr
aac_ltp
aac_he
aac_he_v2
aac_ld
aac_eld
mpeg2_aac_low
mpeg2_aac_he
dts
dts_es
dts_96_24
dts_hd_hra
dts_hd_ma
level integer (encoding,audio,video)
Possible values:
unknown
lowres integer (decoding,audio,video)
Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.
skip_threshold integer (encoding,video)
Set frame skip threshold.
skip_factor integer (encoding,video)
Set frame skip factor.
skip_exp integer (encoding,video)
Set frame skip exponent. Negative values behave identical to the
corresponding positive ones, except that the score is normalized.
Positive values exist primarly for compatibility reasons and are
not so useful.
skipcmp integer (encoding,video)
Set frame skip compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd
sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr
sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero
0
vsad
sum of absolute vertical differences
vsse
sum of squared vertical differences
nsse
noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax
chroma
border_mask float (encoding,video)
Increase the quantizer for macroblocks close to borders.
mblmin integer (encoding,video)
Set min macroblock lagrange factor (VBR).
mblmax integer (encoding,video)
Set max macroblock lagrange factor (VBR).
mepc integer (encoding,video)
Set motion estimation bitrate penalty compensation (1.0 = 256).
skip_loop_filter integer (decoding,video)
skip_idct integer (decoding,video)
skip_frame integer (decoding,video)
Make decoder discard processing depending on the frame type
selected by the option value.
skip_loop_filter skips frame loop filtering, skip_idct skips frame
IDCT/dequantization, skip_frame skips decoding.
Possible values:
none
Discard no frame.
default
Discard useless frames like 0-sized frames.
noref
Discard all non-reference frames.
bidir
Discard all bidirectional frames.
nokey
Discard all frames excepts keyframes.
all Discard all frames.
Default value is default.
bidir_refine integer (encoding,video)
Refine the two motion vectors used in bidirectional macroblocks.
brd_scale integer (encoding,video)
Downscale frames for dynamic B-frame decision.
keyint_min integer (encoding,video)
Set minimum interval between IDR-frames.
refs integer (encoding,video)
Set reference frames to consider for motion compensation.
chromaoffset integer (encoding,video)
Set chroma qp offset from luma.
trellis integer (encoding,audio,video)
Set rate-distortion optimal quantization.
sc_factor integer (encoding,video)
Set value multiplied by qscale for each frame and added to
scene_change_score.
mv0_threshold integer (encoding,video)
b_sensitivity integer (encoding,video)
Adjust sensitivity of b_frame_strategy 1.
compression_level integer (encoding,audio,video)
min_prediction_order integer (encoding,audio)
max_prediction_order integer (encoding,audio)
timecode_frame_start integer (encoding,video)
Set GOP timecode frame start number, in non drop frame format.
request_channels integer (decoding,audio)
Set desired number of audio channels.
bits_per_raw_sample integer
channel_layout integer (decoding/encoding,audio)
Possible values:
request_channel_layout integer (decoding,audio)
Possible values:
rc_max_vbv_use float (encoding,video)
rc_min_vbv_use float (encoding,video)
ticks_per_frame integer (decoding/encoding,audio,video)
color_primaries integer (decoding/encoding,video)
color_trc integer (decoding/encoding,video)
colorspace integer (decoding/encoding,video)
color_range integer (decoding/encoding,video)
chroma_sample_location integer (decoding/encoding,video)
log_level_offset integer
Set the log level offset.
slices integer (encoding,video)
Number of slices, used in parallelized encoding.
thread_type flags (decoding/encoding,video)
Select multithreading type.
Possible values:
slice
frame
audio_service_type integer (encoding,audio)
Set audio service type.
Possible values:
ma Main Audio Service
ef Effects
vi Visually Impaired
hi Hearing Impaired
di Dialogue
co Commentary
em Emergency
vo Voice Over
ka Karaoke
request_sample_fmt sample_fmt (decoding,audio)
Set sample format audio decoders should prefer. Default value is
"none".
pkt_timebase rational number
sub_charenc encoding (decoding,subtitles)
Set the input subtitles character encoding.
field_order field_order (video)
Set/override the field order of the video. Possible values:
progressive
Progressive video
tt Interlaced video, top field coded and displayed first
bb Interlaced video, bottom field coded and displayed first
tb Interlaced video, top coded first, bottom displayed first
bt Interlaced video, bottom coded first, top displayed first
skip_alpha integer (decoding,video)
Set to 1 to disable processing alpha (transparency). This works
like the gray flag in the flags option which skips chroma
information instead of alpha. Default is 0.
DECODERS
Decoders are configured elements in FFmpeg which allow the decoding of
multimedia streams.
When you configure your FFmpeg build, all the supported native decoders
are enabled by default. Decoders requiring an external library must be
enabled manually via the corresponding "--enable-lib" option. You can
list all available decoders using the configure option
"--list-decoders".
You can disable all the decoders with the configure option
"--disable-decoders" and selectively enable / disable single decoders
with the options "--enable-decoder=DECODER" /
"--disable-decoder=DECODER".
The option "-decoders" of the ff* tools will display the list of
enabled decoders.
VIDEO DECODERS
A description of some of the currently available video decoders
follows.
rawvideo
Raw video decoder.
This decoder decodes rawvideo streams.
Options
top top_field_first
Specify the assumed field type of the input video.
-1 the video is assumed to be progressive (default)
0 bottom-field-first is assumed
1 top-field-first is assumed
AUDIO DECODERS
A description of some of the currently available audio decoders
follows.
ac3
AC-3 audio decoder.
This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as
well as the undocumented RealAudio 3 (a.k.a. dnet).
AC-3 Decoder Options
-drc_scale value
Dynamic Range Scale Factor. The factor to apply to dynamic range
values from the AC-3 stream. This factor is applied exponentially.
There are 3 notable scale factor ranges:
drc_scale == 0
DRC disabled. Produces full range audio.
0 < drc_scale <= 1
DRC enabled. Applies a fraction of the stream DRC value.
Audio reproduction is between full range and full compression.
drc_scale > 1
DRC enabled. Applies drc_scale asymmetrically. Loud sounds are
fully compressed. Soft sounds are enhanced.
ffwavesynth
Internal wave synthetizer.
This decoder generates wave patterns according to predefined sequences.
Its use is purely internal and the format of the data it accepts is not
publicly documented.
libcelt
libcelt decoder wrapper.
libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio
codec. Requires the presence of the libcelt headers and library during
configuration. You need to explicitly configure the build with
"--enable-libcelt".
libgsm
libgsm decoder wrapper.
libgsm allows libavcodec to decode the GSM full rate audio codec.
Requires the presence of the libgsm headers and library during
configuration. You need to explicitly configure the build with
"--enable-libgsm".
This decoder supports both the ordinary GSM and the Microsoft variant.
libilbc
libilbc decoder wrapper.
libilbc allows libavcodec to decode the Internet Low Bitrate Codec
(iLBC) audio codec. Requires the presence of the libilbc headers and
library during configuration. You need to explicitly configure the
build with "--enable-libilbc".
Options
The following option is supported by the libilbc wrapper.
enhance
Enable the enhancement of the decoded audio when set to 1. The
default value is 0 (disabled).
libopencore-amrnb
libopencore-amrnb decoder wrapper.
libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
Narrowband audio codec. Using it requires the presence of the
libopencore-amrnb headers and library during configuration. You need to
explicitly configure the build with "--enable-libopencore-amrnb".
An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
without this library.
libopencore-amrwb
libopencore-amrwb decoder wrapper.
libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
Wideband audio codec. Using it requires the presence of the
libopencore-amrwb headers and library during configuration. You need to
explicitly configure the build with "--enable-libopencore-amrwb".
An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
without this library.
libopus
libopus decoder wrapper.
libopus allows libavcodec to decode the Opus Interactive Audio Codec.
Requires the presence of the libopus headers and library during
configuration. You need to explicitly configure the build with
"--enable-libopus".
SUBTITLES DECODERS
dvdsub
This codec decodes the bitmap subtitles used in DVDs; the same
subtitles can also be found in VobSub file pairs and in some Matroska
files.
Options
palette
Specify the global palette used by the bitmaps. When stored in
VobSub, the palette is normally specified in the index file; in
Matroska, the palette is stored in the codec extra-data in the same
format as in VobSub. In DVDs, the palette is stored in the IFO
file, and therefore not available when reading from dumped VOB
files.
The format for this option is a string containing 16 24-bits
hexadecimal numbers (without 0x prefix) separated by comas, for
example "0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b,
0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c,
7c127b".
libzvbi-teletext
Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
subtitles. Requires the presence of the libzvbi headers and library
during configuration. You need to explicitly configure the build with
"--enable-libzvbi".
Options
txt_page
List of teletext page numbers to decode. You may use the special *
string to match all pages. Pages that do not match the specified
list are dropped. Default value is *.
txt_chop_top
Discards the top teletext line. Default value is 1.
txt_format
Specifies the format of the decoded subtitles. The teletext decoder
is capable of decoding the teletext pages to bitmaps or to simple
text, you should use "bitmap" for teletext pages, because certain
graphics and colors cannot be expressed in simple text. You might
use "text" for teletext based subtitles if your application can
handle simple text based subtitles. Default value is bitmap.
txt_left
X offset of generated bitmaps, default is 0.
txt_top
Y offset of generated bitmaps, default is 0.
txt_chop_spaces
Chops leading and trailing spaces and removes empty lines from the
generated text. This option is useful for teletext based subtitles
where empty spaces may be present at the start or at the end of the
lines or empty lines may be present between the subtitle lines
because of double-sized teletext charactes. Default value is 1.
txt_duration
Sets the display duration of the decoded teletext pages or
subtitles in miliseconds. Default value is 30000 which is 30
seconds.
txt_transparent
Force transparent background of the generated teletext bitmaps.
Default value is 0 which means an opaque (black) background.
BITSTREAM FILTERS
When you configure your FFmpeg build, all the supported bitstream
filters are enabled by default. You can list all available ones using
the configure option "--list-bsfs".
You can disable all the bitstream filters using the configure option
"--disable-bsfs", and selectively enable any bitstream filter using the
option "--enable-bsf=BSF", or you can disable a particular bitstream
filter using the option "--disable-bsf=BSF".
The option "-bsfs" of the ff* tools will display the list of all the
supported bitstream filters included in your build.
Below is a description of the currently available bitstream filters.
aac_adtstoasc
Convert MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration
bitstream filter.
This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4 ADTS
header and removes the ADTS header.
This is required for example when copying an AAC stream from a raw ADTS
AAC container to a FLV or a MOV/MP4 file.
chomp
Remove zero padding at the end of a packet.
dump_extra
Add extradata to the beginning of the filtered packets.
The additional argument specifies which packets should be filtered. It
accepts the values:
a add extradata to all key packets, but only if local_header is set
in the flags2 codec context field
k add extradata to all key packets
e add extradata to all packets
If not specified it is assumed k.
For example the following ffmpeg command forces a global header (thus
disabling individual packet headers) in the H.264 packets generated by
the "libx264" encoder, but corrects them by adding the header stored in
extradata to the key packets:
ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts
h264_mp4toannexb
Convert an H.264 bitstream from length prefixed mode to start code
prefixed mode (as defined in the Annex B of the ITU-T H.264
specification).
This is required by some streaming formats, typically the MPEG-2
transport stream format ("mpegts").
For example to remux an MP4 file containing an H.264 stream to mpegts
format with ffmpeg, you can use the command:
ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts
imx_dump_header
mjpeg2jpeg
Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.
MJPEG is a video codec wherein each video frame is essentially a JPEG
image. The individual frames can be extracted without loss, e.g. by
ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg
Unfortunately, these chunks are incomplete JPEG images, because they
lack the DHT segment required for decoding. Quoting from
<http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml>:
Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
commented that "MJPEG, or at least the MJPEG in AVIs having the MJPG
fourcc, is restricted JPEG with a fixed -- and *omitted* -- Huffman
table. The JPEG must be YCbCr colorspace, it must be 4:2:2, and it must
use basic Huffman encoding, not arithmetic or progressive. . . . You
can indeed extract the MJPEG frames and decode them with a regular JPEG
decoder, but you have to prepend the DHT segment to them, or else the
decoder won't have any idea how to decompress the data. The exact table
necessary is given in the OpenDML spec."
This bitstream filter patches the header of frames extracted from an
MJPEG stream (carrying the AVI1 header ID and lacking a DHT segment) to
produce fully qualified JPEG images.
ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
exiftran -i -9 frame*.jpg
ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
mjpega_dump_header
movsub
mp3_header_decompress
noise
remove_extra
FORMAT OPTIONS
The libavformat library provides some generic global options, which can
be set on all the muxers and demuxers. In addition each muxer or
demuxer may support so-called private options, which are specific for
that component.
Options may be set by specifying -option value in the FFmpeg tools, or
by setting the value explicitly in the "AVFormatContext" options or
using the libavutil/opt.h API for programmatic use.
The list of supported options follows:
avioflags flags (input/output)
Possible values:
direct
Reduce buffering.
probesize integer (input)
Set probing size in bytes, i.e. the size of the data to analyze to
get stream information. A higher value will allow to detect more
information in case it is dispersed into the stream, but will
increase latency. Must be an integer not lesser than 32. It is
5000000 by default.
packetsize integer (output)
Set packet size.
fflags flags (input/output)
Set format flags.
Possible values:
ignidx
Ignore index.
genpts
Generate PTS.
nofillin
Do not fill in missing values that can be exactly calculated.
noparse
Disable AVParsers, this needs "+nofillin" too.
igndts
Ignore DTS.
discardcorrupt
Discard corrupted frames.
sortdts
Try to interleave output packets by DTS.
keepside
Do not merge side data.
latm
Enable RTP MP4A-LATM payload.
nobuffer
Reduce the latency introduced by optional buffering
seek2any integer (input)
Allow seeking to non-keyframes on demuxer level when supported if
set to 1. Default is 0.
analyzeduration integer (input)
Specify how many microseconds are analyzed to probe the input. A
higher value will allow to detect more accurate information, but
will increase latency. It defaults to 5,000,000 microseconds = 5
seconds.
cryptokey hexadecimal string (input)
Set decryption key.
indexmem integer (input)
Set max memory used for timestamp index (per stream).
rtbufsize integer (input)
Set max memory used for buffering real-time frames.
fdebug flags (input/output)
Print specific debug info.
Possible values:
ts
max_delay integer (input/output)
Set maximum muxing or demuxing delay in microseconds.
fpsprobesize integer (input)
Set number of frames used to probe fps.
audio_preload integer (output)
Set microseconds by which audio packets should be interleaved
earlier.
chunk_duration integer (output)
Set microseconds for each chunk.
chunk_size integer (output)
Set size in bytes for each chunk.
err_detect, f_err_detect flags (input)
Set error detection flags. "f_err_detect" is deprecated and should
be used only via the ffmpeg tool.
Possible values:
crccheck
Verify embedded CRCs.
bitstream
Detect bitstream specification deviations.
buffer
Detect improper bitstream length.
explode
Abort decoding on minor error detection.
careful
Consider things that violate the spec and have not been seen in
the wild as errors.
compliant
Consider all spec non compliancies as errors.
aggressive
Consider things that a sane encoder should not do as an error.
use_wallclock_as_timestamps integer (input)
Use wallclock as timestamps.
avoid_negative_ts integer (output)
Possible values:
make_non_negative
Shift timestamps to make them non-negative. Also note that
this affects only leading negative timestamps, and not non-
monotonic negative timestamps.
make_zero
Shift timestamps so that the first timestamp is 0.
auto (default)
Enables shifting when required by the target format.
disabled
Disables shifting of timestamp.
When shifting is enabled, all output timestamps are shifted by the
same amount. Audio, video, and subtitles desynching and relative
timestamp differences are preserved compared to how they would have
been without shifting.
skip_initial_bytes integer (input)
Set number of bytes to skip before reading header and frames if set
to 1. Default is 0.
correct_ts_overflow integer (input)
Correct single timestamp overflows if set to 1. Default is 1.
flush_packets integer (output)
Flush the underlying I/O stream after each packet. Default 1
enables it, and has the effect of reducing the latency; 0 disables
it and may slightly increase performance in some cases.
output_ts_offset offset (output)
Set the output time offset.
offset must be a time duration specification, see the Time duration
section in the ffmpeg-utils(1) manual.
The offset is added by the muxer to the output timestamps.
Specifying a positive offset means that the corresponding streams
are delayed bt the time duration specified in offset. Default value
is 0 (meaning that no offset is applied).
Format stream specifiers
Format stream specifiers allow selection of one or more streams that
match specific properties.
Possible forms of stream specifiers are:
stream_index
Matches the stream with this index.
stream_type[:stream_index]
stream_type is one of following: 'v' for video, 'a' for audio, 's'
for subtitle, 'd' for data, and 't' for attachments. If
stream_index is given, then it matches the stream number
stream_index of this type. Otherwise, it matches all streams of
this type.
p:program_id[:stream_index]
If stream_index is given, then it matches the stream with number
stream_index in the program with the id program_id. Otherwise, it
matches all streams in the program.
#stream_id
Matches the stream by a format-specific ID.
The exact semantics of stream specifiers is defined by the
"avformat_match_stream_specifier()" function declared in the
libavformat/avformat.h header.
DEMUXERS
Demuxers are configured elements in FFmpeg that can read the multimedia
streams from a particular type of file.
When you configure your FFmpeg build, all the supported demuxers are
enabled by default. You can list all available ones using the configure
option "--list-demuxers".
You can disable all the demuxers using the configure option
"--disable-demuxers", and selectively enable a single demuxer with the
option "--enable-demuxer=DEMUXER", or disable it with the option
"--disable-demuxer=DEMUXER".
The option "-formats" of the ff* tools will display the list of enabled
demuxers.
The description of some of the currently available demuxers follows.
applehttp
Apple HTTP Live Streaming demuxer.
This demuxer presents all AVStreams from all variant streams. The id
field is set to the bitrate variant index number. By setting the
discard flags on AVStreams (by pressing 'a' or 'v' in ffplay), the
caller can decide which variant streams to actually receive. The total
bitrate of the variant that the stream belongs to is available in a
metadata key named "variant_bitrate".
asf
Advanced Systems Format demuxer.
This demuxer is used to demux ASF files and MMS network streams.
-no_resync_search bool
Do not try to resynchronize by looking for a certain optional start
code.
concat
Virtual concatenation script demuxer.
This demuxer reads a list of files and other directives from a text
file and demuxes them one after the other, as if all their packet had
been muxed together.
The timestamps in the files are adjusted so that the first file starts
at 0 and each next file starts where the previous one finishes. Note
that it is done globally and may cause gaps if all streams do not have
exactly the same length.
All files must have the same streams (same codecs, same time base,
etc.).
The duration of each file is used to adjust the timestamps of the next
file: if the duration is incorrect (because it was computed using the
bit-rate or because the file is truncated, for example), it can cause
artifacts. The "duration" directive can be used to override the
duration stored in each file.
Syntax
The script is a text file in extended-ASCII, with one directive per
line. Empty lines, leading spaces and lines starting with '#' are
ignored. The following directive is recognized:
"file path"
Path to a file to read; special characters and spaces must be
escaped with backslash or single quotes.
All subsequent directives apply to that file.
"ffconcat version 1.0"
Identify the script type and version. It also sets the safe option
to 1 if it was to its default -1.
To make FFmpeg recognize the format automatically, this directive
must appears exactly as is (no extra space or byte-order-mark) on
the very first line of the script.
"duration dur"
Duration of the file. This information can be specified from the
file; specifying it here may be more efficient or help if the
information from the file is not available or accurate.
If the duration is set for all files, then it is possible to seek
in the whole concatenated video.
Options
This demuxer accepts the following option:
safe
If set to 1, reject unsafe file paths. A file path is considered
safe if it does not contain a protocol specification and is
relative and all components only contain characters from the
portable character set (letters, digits, period, underscore and
hyphen) and have no period at the beginning of a component.
If set to 0, any file name is accepted.
The default is -1, it is equivalent to 1 if the format was
automatically probed and 0 otherwise.
flv
Adobe Flash Video Format demuxer.
This demuxer is used to demux FLV files and RTMP network streams.
-flv_metadata bool
Allocate the streams according to the onMetaData array content.
libgme
The Game Music Emu library is a collection of video game music file
emulators.
See <http://code.google.com/p/game-music-emu/> for more information.
Some files have multiple tracks. The demuxer will pick the first track
by default. The track_index option can be used to select a different
track. Track indexes start at 0. The demuxer exports the number of
tracks as tracks meta data entry.
For very large files, the max_size option may have to be adjusted.
libquvi
Play media from Internet services using the quvi project.
The demuxer accepts a format option to request a specific quality. It
is by default set to best.
See <http://quvi.sourceforge.net/> for more information.
FFmpeg needs to be built with "--enable-libquvi" for this demuxer to be
enabled.
image2
Image file demuxer.
This demuxer reads from a list of image files specified by a pattern.
The syntax and meaning of the pattern is specified by the option
pattern_type.
The pattern may contain a suffix which is used to automatically
determine the format of the images contained in the files.
The size, the pixel format, and the format of each image must be the
same for all the files in the sequence.
This demuxer accepts the following options:
framerate
Set the frame rate for the video stream. It defaults to 25.
loop
If set to 1, loop over the input. Default value is 0.
pattern_type
Select the pattern type used to interpret the provided filename.
pattern_type accepts one of the following values.
sequence
Select a sequence pattern type, used to specify a sequence of
files indexed by sequential numbers.
A sequence pattern may contain the string "%d" or "%0Nd", which
specifies the position of the characters representing a
sequential number in each filename matched by the pattern. If
the form "%d0Nd" is used, the string representing the number in
each filename is 0-padded and N is the total number of 0-padded
digits representing the number. The literal character '%' can
be specified in the pattern with the string "%%".
If the sequence pattern contains "%d" or "%0Nd", the first
filename of the file list specified by the pattern must contain
a number inclusively contained between start_number and
start_number+start_number_range-1, and all the following
numbers must be sequential.
For example the pattern "img-%03d.bmp" will match a sequence of
filenames of the form img-001.bmp, img-002.bmp, ...,
img-010.bmp, etc.; the pattern "i%%m%%g-%d.jpg" will match a
sequence of filenames of the form i%m%g-1.jpg, i%m%g-2.jpg,
..., i%m%g-10.jpg, etc.
Note that the pattern must not necessarily contain "%d" or
"%0Nd", for example to convert a single image file img.jpeg you
can employ the command:
ffmpeg -i img.jpeg img.png
glob
Select a glob wildcard pattern type.
The pattern is interpreted like a "glob()" pattern. This is
only selectable if libavformat was compiled with globbing
support.
glob_sequence (deprecated, will be removed)
Select a mixed glob wildcard/sequence pattern.
If your version of libavformat was compiled with globbing
support, and the provided pattern contains at least one glob
meta character among "%*?[]{}" that is preceded by an unescaped
"%", the pattern is interpreted like a "glob()" pattern,
otherwise it is interpreted like a sequence pattern.
All glob special characters "%*?[]{}" must be prefixed with
"%". To escape a literal "%" you shall use "%%".
For example the pattern "foo-%*.jpeg" will match all the
filenames prefixed by "foo-" and terminating with ".jpeg", and
"foo-%?%?%?.jpeg" will match all the filenames prefixed with
"foo-", followed by a sequence of three characters, and
terminating with ".jpeg".
This pattern type is deprecated in favor of glob and sequence.
Default value is glob_sequence.
pixel_format
Set the pixel format of the images to read. If not specified the
pixel format is guessed from the first image file in the sequence.
start_number
Set the index of the file matched by the image file pattern to
start to read from. Default value is 0.
start_number_range
Set the index interval range to check when looking for the first
image file in the sequence, starting from start_number. Default
value is 5.
ts_from_file
If set to 1, will set frame timestamp to modification time of image
file. Note that monotonity of timestamps is not provided: images go
in the same order as without this option. Default value is 0.
video_size
Set the video size of the images to read. If not specified the
video size is guessed from the first image file in the sequence.
Examples
· Use ffmpeg for creating a video from the images in the file
sequence img-001.jpeg, img-002.jpeg, ..., assuming an input frame
rate of 10 frames per second:
ffmpeg -framerate 10 -i 'img-%03d.jpeg' out.mkv
· As above, but start by reading from a file with index 100 in the
sequence:
ffmpeg -framerate 10 -start_number 100 -i 'img-%03d.jpeg' out.mkv
· Read images matching the "*.png" glob pattern , that is all the
files terminating with the ".png" suffix:
ffmpeg -framerate 10 -pattern_type glob -i "*.png" out.mkv
mpegts
MPEG-2 transport stream demuxer.
fix_teletext_pts
Overrides teletext packet PTS and DTS values with the timestamps
calculated from the PCR of the first program which the teletext
stream is part of and is not discarded. Default value is 1, set
this option to 0 if you want your teletext packet PTS and DTS
values untouched.
rawvideo
Raw video demuxer.
This demuxer allows one to read raw video data. Since there is no
header specifying the assumed video parameters, the user must specify
them in order to be able to decode the data correctly.
This demuxer accepts the following options:
framerate
Set input video frame rate. Default value is 25.
pixel_format
Set the input video pixel format. Default value is "yuv420p".
video_size
Set the input video size. This value must be specified explicitly.
For example to read a rawvideo file input.raw with ffplay, assuming a
pixel format of "rgb24", a video size of "320x240", and a frame rate of
10 images per second, use the command:
ffplay -f rawvideo -pixel_format rgb24 -video_size 320x240 -framerate 10 input.raw
sbg
SBaGen script demuxer.
This demuxer reads the script language used by SBaGen
<http://uazu.net/sbagen/> to generate binaural beats sessions. A SBG
script looks like that:
-SE
a: 300-2.5/3 440+4.5/0
b: 300-2.5/0 440+4.5/3
off: -
NOW == a
+0:07:00 == b
+0:14:00 == a
+0:21:00 == b
+0:30:00 off
A SBG script can mix absolute and relative timestamps. If the script
uses either only absolute timestamps (including the script start time)
or only relative ones, then its layout is fixed, and the conversion is
straightforward. On the other hand, if the script mixes both kind of
timestamps, then the NOW reference for relative timestamps will be
taken from the current time of day at the time the script is read, and
the script layout will be frozen according to that reference. That
means that if the script is directly played, the actual times will
match the absolute timestamps up to the sound controller's clock
accuracy, but if the user somehow pauses the playback or seeks, all
times will be shifted accordingly.
tedcaptions
JSON captions used for <http://www.ted.com/>.
TED does not provide links to the captions, but they can be guessed
from the page. The file tools/bookmarklets.html from the FFmpeg source
tree contains a bookmarklet to expose them.
This demuxer accepts the following option:
start_time
Set the start time of the TED talk, in milliseconds. The default is
15000 (15s). It is used to sync the captions with the downloadable
videos, because they include a 15s intro.
Example: convert the captions to a format most players understand:
ffmpeg -i http://www.ted.com/talks/subtitles/id/1/lang/en talk1-en.srt
METADATA
FFmpeg is able to dump metadata from media files into a simple
UTF-8-encoded INI-like text file and then load it back using the
metadata muxer/demuxer.
The file format is as follows:
1. A file consists of a header and a number of metadata tags divided
into sections, each on its own line.
2. The header is a ';FFMETADATA' string, followed by a version number
(now 1).
3. Metadata tags are of the form 'key=value'
4. Immediately after header follows global metadata
5. After global metadata there may be sections with
per-stream/per-chapter metadata.
6. A section starts with the section name in uppercase (i.e. STREAM or
CHAPTER) in brackets ('[', ']') and ends with next section or end
of file.
7. At the beginning of a chapter section there may be an optional
timebase to be used for start/end values. It must be in form
'TIMEBASE=num/den', where num and den are integers. If the timebase
is missing then start/end times are assumed to be in milliseconds.
Next a chapter section must contain chapter start and end times in
form 'START=num', 'END=num', where num is a positive integer.
8. Empty lines and lines starting with ';' or '#' are ignored.
9. Metadata keys or values containing special characters ('=', ';',
'#', '\' and a newline) must be escaped with a backslash '\'.
10. Note that whitespace in metadata (e.g. foo = bar) is considered to
be a part of the tag (in the example above key is 'foo ', value is
' bar').
A ffmetadata file might look like this:
;FFMETADATA1
title=bike\\shed
;this is a comment
artist=FFmpeg troll team
[CHAPTER]
TIMEBASE=1/1000
START=0
#chapter ends at 0:01:00
END=60000
title=chapter \#1
[STREAM]
title=multi\
line
By using the ffmetadata muxer and demuxer it is possible to extract
metadata from an input file to an ffmetadata file, and then transcode
the file into an output file with the edited ffmetadata file.
Extracting an ffmetadata file with ffmpeg goes as follows:
ffmpeg -i INPUT -f ffmetadata FFMETADATAFILE
Reinserting edited metadata information from the FFMETADATAFILE file
can be done as:
ffmpeg -i INPUT -i FFMETADATAFILE -map_metadata 1 -codec copy OUTPUT
PROTOCOLS
Protocols are configured elements in FFmpeg that enable access to
resources that require specific protocols.
When you configure your FFmpeg build, all the supported protocols are
enabled by default. You can list all available ones using the configure
option "--list-protocols".
You can disable all the protocols using the configure option
"--disable-protocols", and selectively enable a protocol using the
option "--enable-protocol=PROTOCOL", or you can disable a particular
protocol using the option "--disable-protocol=PROTOCOL".
The option "-protocols" of the ff* tools will display the list of
supported protocols.
A description of the currently available protocols follows.
bluray
Read BluRay playlist.
The accepted options are:
angle
BluRay angle
chapter
Start chapter (1...N)
playlist
Playlist to read (BDMV/PLAYLIST/?????.mpls)
Examples:
Read longest playlist from BluRay mounted to /mnt/bluray:
bluray:/mnt/bluray
Read angle 2 of playlist 4 from BluRay mounted to /mnt/bluray, start
from chapter 2:
-playlist 4 -angle 2 -chapter 2 bluray:/mnt/bluray
cache
Caching wrapper for input stream.
Cache the input stream to temporary file. It brings seeking capability
to live streams.
cache:<URL>
concat
Physical concatenation protocol.
Allow to read and seek from many resource in sequence as if they were a
unique resource.
A URL accepted by this protocol has the syntax:
concat:<URL1>|<URL2>|...|<URLN>
where URL1, URL2, ..., URLN are the urls of the resource to be
concatenated, each one possibly specifying a distinct protocol.
For example to read a sequence of files split1.mpeg, split2.mpeg,
split3.mpeg with ffplay use the command:
ffplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg
Note that you may need to escape the character "|" which is special for
many shells.
crypto
AES-encrypted stream reading protocol.
The accepted options are:
key Set the AES decryption key binary block from given hexadecimal
representation.
iv Set the AES decryption initialization vector binary block from
given hexadecimal representation.
Accepted URL formats:
crypto:<URL>
crypto+<URL>
data
Data in-line in the URI. See
<http://en.wikipedia.org/wiki/Data_URI_scheme>.
For example, to convert a GIF file given inline with ffmpeg:
ffmpeg -i "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywAAAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png
file
File access protocol.
Allow to read from or write to a file.
A file URL can have the form:
file:<filename>
where filename is the path of the file to read.
An URL that does not have a protocol prefix will be assumed to be a
file URL. Depending on the build, an URL that looks like a Windows path
with the drive letter at the beginning will also be assumed to be a
file URL (usually not the case in builds for unix-like systems).
For example to read from a file input.mpeg with ffmpeg use the command:
ffmpeg -i file:input.mpeg output.mpeg
This protocol accepts the following options:
truncate
Truncate existing files on write, if set to 1. A value of 0
prevents truncating. Default value is 1.
blocksize
Set I/O operation maximum block size, in bytes. Default value is
"INT_MAX", which results in not limiting the requested block size.
Setting this value reasonably low improves user termination request
reaction time, which is valuable for files on slow medium.
ftp
FTP (File Transfer Protocol).
Allow to read from or write to remote resources using FTP protocol.
Following syntax is required.
ftp://[user[:password]@]server[:port]/path/to/remote/resource.mpeg
This protocol accepts the following options.
timeout
Set timeout of socket I/O operations used by the underlying low
level operation. By default it is set to -1, which means that the
timeout is not specified.
ftp-anonymous-password
Password used when login as anonymous user. Typically an e-mail
address should be used.
ftp-write-seekable
Control seekability of connection during encoding. If set to 1 the
resource is supposed to be seekable, if set to 0 it is assumed not
to be seekable. Default value is 0.
NOTE: Protocol can be used as output, but it is recommended to not do
it, unless special care is taken (tests, customized server
configuration etc.). Different FTP servers behave in different way
during seek operation. ff* tools may produce incomplete content due to
server limitations.
gopher
Gopher protocol.
hls
Read Apple HTTP Live Streaming compliant segmented stream as a uniform
one. The M3U8 playlists describing the segments can be remote HTTP
resources or local files, accessed using the standard file protocol.
The nested protocol is declared by specifying "+proto" after the hls
URI scheme name, where proto is either "file" or "http".
hls+http://host/path/to/remote/resource.m3u8
hls+file://path/to/local/resource.m3u8
Using this protocol is discouraged - the hls demuxer should work just
as well (if not, please report the issues) and is more complete. To
use the hls demuxer instead, simply use the direct URLs to the m3u8
files.
http
HTTP (Hyper Text Transfer Protocol).
This protocol accepts the following options:
seekable
Control seekability of connection. If set to 1 the resource is
supposed to be seekable, if set to 0 it is assumed not to be
seekable, if set to -1 it will try to autodetect if it is seekable.
Default value is -1.
chunked_post
If set to 1 use chunked Transfer-Encoding for posts, default is 1.
content_type
Set a specific content type for the POST messages.
headers
Set custom HTTP headers, can override built in default headers. The
value must be a string encoding the headers.
multiple_requests
Use persistent connections if set to 1, default is 0.
post_data
Set custom HTTP post data.
user-agent
user_agent
Override the User-Agent header. If not specified the protocol will
use a string describing the libavformat build. ("Lavf/<version>")
timeout
Set timeout of socket I/O operations used by the underlying low
level operation. By default it is set to -1, which means that the
timeout is not specified.
mime_type
Export the MIME type.
icy If set to 1 request ICY (SHOUTcast) metadata from the server. If
the server supports this, the metadata has to be retrieved by the
application by reading the icy_metadata_headers and
icy_metadata_packet options. The default is 0.
icy_metadata_headers
If the server supports ICY metadata, this contains the ICY-specific
HTTP reply headers, separated by newline characters.
icy_metadata_packet
If the server supports ICY metadata, and icy was set to 1, this
contains the last non-empty metadata packet sent by the server. It
should be polled in regular intervals by applications interested in
mid-stream metadata updates.
cookies
Set the cookies to be sent in future requests. The format of each
cookie is the same as the value of a Set-Cookie HTTP response
field. Multiple cookies can be delimited by a newline character.
offset
Set initial byte offset.
end_offset
Try to limit the request to bytes preceding this offset.
HTTP Cookies
Some HTTP requests will be denied unless cookie values are passed in
with the request. The cookies option allows these cookies to be
specified. At the very least, each cookie must specify a value along
with a path and domain. HTTP requests that match both the domain and
path will automatically include the cookie value in the HTTP Cookie
header field. Multiple cookies can be delimited by a newline.
The required syntax to play a stream specifying a cookie is:
ffplay -cookies "nlqptid=nltid=tsn; path=/; domain=somedomain.com;" http://somedomain.com/somestream.m3u8
mmst
MMS (Microsoft Media Server) protocol over TCP.
mmsh
MMS (Microsoft Media Server) protocol over HTTP.
The required syntax is:
mmsh://<server>[:<port>][/<app>][/<playpath>]
md5
MD5 output protocol.
Computes the MD5 hash of the data to be written, and on close writes
this to the designated output or stdout if none is specified. It can be
used to test muxers without writing an actual file.
Some examples follow.
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
ffmpeg -i input.flv -f avi -y md5:output.avi.md5
# Write the MD5 hash of the encoded AVI file to stdout.
ffmpeg -i input.flv -f avi -y md5:
Note that some formats (typically MOV) require the output protocol to
be seekable, so they will fail with the MD5 output protocol.
pipe
UNIX pipe access protocol.
Allow to read and write from UNIX pipes.
The accepted syntax is:
pipe:[<number>]
number is the number corresponding to the file descriptor of the pipe
(e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number is not
specified, by default the stdout file descriptor will be used for
writing, stdin for reading.
For example to read from stdin with ffmpeg:
cat test.wav | ffmpeg -i pipe:0
# ...this is the same as...
cat test.wav | ffmpeg -i pipe:
For writing to stdout with ffmpeg:
ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
# ...this is the same as...
ffmpeg -i test.wav -f avi pipe: | cat > test.avi
This protocol accepts the following options:
blocksize
Set I/O operation maximum block size, in bytes. Default value is
"INT_MAX", which results in not limiting the requested block size.
Setting this value reasonably low improves user termination request
reaction time, which is valuable if data transmission is slow.
Note that some formats (typically MOV), require the output protocol to
be seekable, so they will fail with the pipe output protocol.
rtmp
Real-Time Messaging Protocol.
The Real-Time Messaging Protocol (RTMP) is used for streaming
multimedia content across a TCP/IP network.
The required syntax is:
rtmp://[<username>:<password>@]<server>[:<port>][/<app>][/<instance>][/<playpath>]
The accepted parameters are:
username
An optional username (mostly for publishing).
password
An optional password (mostly for publishing).
server
The address of the RTMP server.
port
The number of the TCP port to use (by default is 1935).
app It is the name of the application to access. It usually corresponds
to the path where the application is installed on the RTMP server
(e.g. /ondemand/, /flash/live/, etc.). You can override the value
parsed from the URI through the "rtmp_app" option, too.
playpath
It is the path or name of the resource to play with reference to
the application specified in app, may be prefixed by "mp4:". You
can override the value parsed from the URI through the
"rtmp_playpath" option, too.
listen
Act as a server, listening for an incoming connection.
timeout
Maximum time to wait for the incoming connection. Implies listen.
Additionally, the following parameters can be set via command line
options (or in code via "AVOption"s):
rtmp_app
Name of application to connect on the RTMP server. This option
overrides the parameter specified in the URI.
rtmp_buffer
Set the client buffer time in milliseconds. The default is 3000.
rtmp_conn
Extra arbitrary AMF connection parameters, parsed from a string,
e.g. like "B:1 S:authMe O:1 NN:code:1.23 NS:flag:ok O:0". Each
value is prefixed by a single character denoting the type, B for
Boolean, N for number, S for string, O for object, or Z for null,
followed by a colon. For Booleans the data must be either 0 or 1
for FALSE or TRUE, respectively. Likewise for Objects the data
must be 0 or 1 to end or begin an object, respectively. Data items
in subobjects may be named, by prefixing the type with 'N' and
specifying the name before the value (i.e. "NB:myFlag:1"). This
option may be used multiple times to construct arbitrary AMF
sequences.
rtmp_flashver
Version of the Flash plugin used to run the SWF player. The default
is LNX 9,0,124,2. (When publishing, the default is FMLE/3.0
(compatible; <libavformat version>).)
rtmp_flush_interval
Number of packets flushed in the same request (RTMPT only). The
default is 10.
rtmp_live
Specify that the media is a live stream. No resuming or seeking in
live streams is possible. The default value is "any", which means
the subscriber first tries to play the live stream specified in the
playpath. If a live stream of that name is not found, it plays the
recorded stream. The other possible values are "live" and
"recorded".
rtmp_pageurl
URL of the web page in which the media was embedded. By default no
value will be sent.
rtmp_playpath
Stream identifier to play or to publish. This option overrides the
parameter specified in the URI.
rtmp_subscribe
Name of live stream to subscribe to. By default no value will be
sent. It is only sent if the option is specified or if rtmp_live
is set to live.
rtmp_swfhash
SHA256 hash of the decompressed SWF file (32 bytes).
rtmp_swfsize
Size of the decompressed SWF file, required for SWFVerification.
rtmp_swfurl
URL of the SWF player for the media. By default no value will be
sent.
rtmp_swfverify
URL to player swf file, compute hash/size automatically.
rtmp_tcurl
URL of the target stream. Defaults to proto://host[:port]/app.
For example to read with ffplay a multimedia resource named "sample"
from the application "vod" from an RTMP server "myserver":
ffplay rtmp://myserver/vod/sample
To publish to a password protected server, passing the playpath and app
names separately:
ffmpeg -re -i <input> -f flv -rtmp_playpath some/long/path -rtmp_app long/app/name rtmp://username:password@myserver/
rtmpe
Encrypted Real-Time Messaging Protocol.
The Encrypted Real-Time Messaging Protocol (RTMPE) is used for
streaming multimedia content within standard cryptographic primitives,
consisting of Diffie-Hellman key exchange and HMACSHA256, generating a
pair of RC4 keys.
rtmps
Real-Time Messaging Protocol over a secure SSL connection.
The Real-Time Messaging Protocol (RTMPS) is used for streaming
multimedia content across an encrypted connection.
rtmpt
Real-Time Messaging Protocol tunneled through HTTP.
The Real-Time Messaging Protocol tunneled through HTTP (RTMPT) is used
for streaming multimedia content within HTTP requests to traverse
firewalls.
rtmpte
Encrypted Real-Time Messaging Protocol tunneled through HTTP.
The Encrypted Real-Time Messaging Protocol tunneled through HTTP
(RTMPTE) is used for streaming multimedia content within HTTP requests
to traverse firewalls.
rtmpts
Real-Time Messaging Protocol tunneled through HTTPS.
The Real-Time Messaging Protocol tunneled through HTTPS (RTMPTS) is
used for streaming multimedia content within HTTPS requests to traverse
firewalls.
libssh
Secure File Transfer Protocol via libssh
Allow to read from or write to remote resources using SFTP protocol.
Following syntax is required.
sftp://[user[:password]@]server[:port]/path/to/remote/resource.mpeg
This protocol accepts the following options.
timeout
Set timeout of socket I/O operations used by the underlying low
level operation. By default it is set to -1, which means that the
timeout is not specified.
truncate
Truncate existing files on write, if set to 1. A value of 0
prevents truncating. Default value is 1.
private_key
Specify the path of the file containing private key to use during
authorization. By default libssh searches for keys in the ~/.ssh/
directory.
Example: Play a file stored on remote server.
ffplay sftp://user:password@server_address:22/home/user/resource.mpeg
librtmp rtmp, rtmpe, rtmps, rtmpt, rtmpte
Real-Time Messaging Protocol and its variants supported through
librtmp.
Requires the presence of the librtmp headers and library during
configuration. You need to explicitly configure the build with
"--enable-librtmp". If enabled this will replace the native RTMP
protocol.
This protocol provides most client functions and a few server functions
needed to support RTMP, RTMP tunneled in HTTP (RTMPT), encrypted RTMP
(RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled variants of these
encrypted types (RTMPTE, RTMPTS).
The required syntax is:
<rtmp_proto>://<server>[:<port>][/<app>][/<playpath>] <options>
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
server, port, app and playpath have the same meaning as specified for
the RTMP native protocol. options contains a list of space-separated
options of the form key=val.
See the librtmp manual page (man 3 librtmp) for more information.
For example, to stream a file in real-time to an RTMP server using
ffmpeg:
ffmpeg -re -i myfile -f flv rtmp://myserver/live/mystream
To play the same stream using ffplay:
ffplay "rtmp://myserver/live/mystream live=1"
rtp
Real-time Transport Protocol.
The required syntax for an RTP URL is:
rtp://hostname[:port][?option=val...]
port specifies the RTP port to use.
The following URL options are supported:
ttl=n
Set the TTL (Time-To-Live) value (for multicast only).
rtcpport=n
Set the remote RTCP port to n.
localrtpport=n
Set the local RTP port to n.
localrtcpport=n'
Set the local RTCP port to n.
pkt_size=n
Set max packet size (in bytes) to n.
connect=0|1
Do a "connect()" on the UDP socket (if set to 1) or not (if set to
0).
sources=ip[,ip]
List allowed source IP addresses.
block=ip[,ip]
List disallowed (blocked) source IP addresses.
write_to_source=0|1
Send packets to the source address of the latest received packet
(if set to 1) or to a default remote address (if set to 0).
localport=n
Set the local RTP port to n.
This is a deprecated option. Instead, localrtpport should be used.
Important notes:
1. If rtcpport is not set the RTCP port will be set to the RTP port
value plus 1.
2. If localrtpport (the local RTP port) is not set any available port
will be used for the local RTP and RTCP ports.
3. If localrtcpport (the local RTCP port) is not set it will be set to
the the local RTP port value plus 1.
rtsp
Real-Time Streaming Protocol.
RTSP is not technically a protocol handler in libavformat, it is a
demuxer and muxer. The demuxer supports both normal RTSP (with data
transferred over RTP; this is used by e.g. Apple and Microsoft) and
Real-RTSP (with data transferred over RDT).
The muxer can be used to send a stream using RTSP ANNOUNCE to a server
supporting it (currently Darwin Streaming Server and Mischa
Spiegelmock's <http://github.com/revmischa/rtsp-server>).
The required syntax for a RTSP url is:
rtsp://<hostname>[:<port>]/<path>
Options can be set on the ffmpeg/ffplay command line, or set in code
via "AVOption"s or in "avformat_open_input".
The following options are supported.
initial_pause
Do not start playing the stream immediately if set to 1. Default
value is 0.
rtsp_transport
Set RTSP trasport protocols.
It accepts the following values:
udp Use UDP as lower transport protocol.
tcp Use TCP (interleaving within the RTSP control channel) as lower
transport protocol.
udp_multicast
Use UDP multicast as lower transport protocol.
http
Use HTTP tunneling as lower transport protocol, which is useful
for passing proxies.
Multiple lower transport protocols may be specified, in that case
they are tried one at a time (if the setup of one fails, the next
one is tried). For the muxer, only the tcp and udp options are
supported.
rtsp_flags
Set RTSP flags.
The following values are accepted:
filter_src
Accept packets only from negotiated peer address and port.
listen
Act as a server, listening for an incoming connection.
Default value is none.
allowed_media_types
Set media types to accept from the server.
The following flags are accepted:
video
audio
data
By default it accepts all media types.
min_port
Set minimum local UDP port. Default value is 5000.
max_port
Set maximum local UDP port. Default value is 65000.
timeout
Set maximum timeout (in seconds) to wait for incoming connections.
A value of -1 mean infinite (default). This option implies the
rtsp_flags set to listen.
reorder_queue_size
Set number of packets to buffer for handling of reordered packets.
stimeout
Set socket TCP I/O timeout in micro seconds.
user-agent
Override User-Agent header. If not specified, it default to the
libavformat identifier string.
When receiving data over UDP, the demuxer tries to reorder received
packets (since they may arrive out of order, or packets may get lost
totally). This can be disabled by setting the maximum demuxing delay to
zero (via the "max_delay" field of AVFormatContext).
When watching multi-bitrate Real-RTSP streams with ffplay, the streams
to display can be chosen with "-vst" n and "-ast" n for video and audio
respectively, and can be switched on the fly by pressing "v" and "a".
Examples
The following examples all make use of the ffplay and ffmpeg tools.
· Watch a stream over UDP, with a max reordering delay of 0.5
seconds:
ffplay -max_delay 500000 -rtsp_transport udp rtsp://server/video.mp4
· Watch a stream tunneled over HTTP:
ffplay -rtsp_transport http rtsp://server/video.mp4
· Send a stream in realtime to a RTSP server, for others to watch:
ffmpeg -re -i <input> -f rtsp -muxdelay 0.1 rtsp://server/live.sdp
· Receive a stream in realtime:
ffmpeg -rtsp_flags listen -i rtsp://ownaddress/live.sdp <output>
sap
Session Announcement Protocol (RFC 2974). This is not technically a
protocol handler in libavformat, it is a muxer and demuxer. It is used
for signalling of RTP streams, by announcing the SDP for the streams
regularly on a separate port.
Muxer
The syntax for a SAP url given to the muxer is:
sap://<destination>[:<port>][?<options>]
The RTP packets are sent to destination on port port, or to port 5004
if no port is specified. options is a "&"-separated list. The
following options are supported:
announce_addr=address
Specify the destination IP address for sending the announcements
to. If omitted, the announcements are sent to the commonly used
SAP announcement multicast address 224.2.127.254 (sap.mcast.net),
or ff0e::2:7ffe if destination is an IPv6 address.
announce_port=port
Specify the port to send the announcements on, defaults to 9875 if
not specified.
ttl=ttl
Specify the time to live value for the announcements and RTP
packets, defaults to 255.
same_port=0|1
If set to 1, send all RTP streams on the same port pair. If zero
(the default), all streams are sent on unique ports, with each
stream on a port 2 numbers higher than the previous. VLC/Live555
requires this to be set to 1, to be able to receive the stream.
The RTP stack in libavformat for receiving requires all streams to
be sent on unique ports.
Example command lines follow.
To broadcast a stream on the local subnet, for watching in VLC:
ffmpeg -re -i <input> -f sap sap://224.0.0.255?same_port=1
Similarly, for watching in ffplay:
ffmpeg -re -i <input> -f sap sap://224.0.0.255
And for watching in ffplay, over IPv6:
ffmpeg -re -i <input> -f sap sap://[ff0e::1:2:3:4]
Demuxer
The syntax for a SAP url given to the demuxer is:
sap://[<address>][:<port>]
address is the multicast address to listen for announcements on, if
omitted, the default 224.2.127.254 (sap.mcast.net) is used. port is the
port that is listened on, 9875 if omitted.
The demuxers listens for announcements on the given address and port.
Once an announcement is received, it tries to receive that particular
stream.
Example command lines follow.
To play back the first stream announced on the normal SAP multicast
address:
ffplay sap://
To play back the first stream announced on one the default IPv6 SAP
multicast address:
ffplay sap://[ff0e::2:7ffe]
sctp
Stream Control Transmission Protocol.
The accepted URL syntax is:
sctp://<host>:<port>[?<options>]
The protocol accepts the following options:
listen
If set to any value, listen for an incoming connection. Outgoing
connection is done by default.
max_streams
Set the maximum number of streams. By default no limit is set.
srtp
Secure Real-time Transport Protocol.
The accepted options are:
srtp_in_suite
srtp_out_suite
Select input and output encoding suites.
Supported values:
AES_CM_128_HMAC_SHA1_80
SRTP_AES128_CM_HMAC_SHA1_80
AES_CM_128_HMAC_SHA1_32
SRTP_AES128_CM_HMAC_SHA1_32
srtp_in_params
srtp_out_params
Set input and output encoding parameters, which are expressed by a
base64-encoded representation of a binary block. The first 16 bytes
of this binary block are used as master key, the following 14 bytes
are used as master salt.
tcp
Transmission Control Protocol.
The required syntax for a TCP url is:
tcp://<hostname>:<port>[?<options>]
options contains a list of &-separated options of the form key=val.
The list of supported options follows.
listen=1|0
Listen for an incoming connection. Default value is 0.
timeout=microseconds
Set raise error timeout, expressed in microseconds.
This option is only relevant in read mode: if no data arrived in
more than this time interval, raise error.
listen_timeout=microseconds
Set listen timeout, expressed in microseconds.
The following example shows how to setup a listening TCP connection
with ffmpeg, which is then accessed with ffplay:
ffmpeg -i <input> -f <format> tcp://<hostname>:<port>?listen
ffplay tcp://<hostname>:<port>
tls
Transport Layer Security (TLS) / Secure Sockets Layer (SSL)
The required syntax for a TLS/SSL url is:
tls://<hostname>:<port>[?<options>]
The following parameters can be set via command line options (or in
code via "AVOption"s):
ca_file, cafile=filename
A file containing certificate authority (CA) root certificates to
treat as trusted. If the linked TLS library contains a default this
might not need to be specified for verification to work, but not
all libraries and setups have defaults built in. The file must be
in OpenSSL PEM format.
tls_verify=1|0
If enabled, try to verify the peer that we are communicating with.
Note, if using OpenSSL, this currently only makes sure that the
peer certificate is signed by one of the root certificates in the
CA database, but it does not validate that the certificate actually
matches the host name we are trying to connect to. (With GnuTLS,
the host name is validated as well.)
This is disabled by default since it requires a CA database to be
provided by the caller in many cases.
cert_file, cert=filename
A file containing a certificate to use in the handshake with the
peer. (When operating as server, in listen mode, this is more
often required by the peer, while client certificates only are
mandated in certain setups.)
key_file, key=filename
A file containing the private key for the certificate.
listen=1|0
If enabled, listen for connections on the provided port, and assume
the server role in the handshake instead of the client role.
Example command lines:
To create a TLS/SSL server that serves an input stream.
ffmpeg -i <input> -f <format> tls://<hostname>:<port>?listen&cert=<server.crt>&key=<server.key>
To play back a stream from the TLS/SSL server using ffplay:
ffplay tls://<hostname>:<port>
udp
User Datagram Protocol.
The required syntax for an UDP URL is:
udp://<hostname>:<port>[?<options>]
options contains a list of &-separated options of the form key=val.
In case threading is enabled on the system, a circular buffer is used
to store the incoming data, which allows one to reduce loss of data due
to UDP socket buffer overruns. The fifo_size and overrun_nonfatal
options are related to this buffer.
The list of supported options follows.
buffer_size=size
Set the UDP socket buffer size in bytes. This is used both for the
receiving and the sending buffer size.
localport=port
Override the local UDP port to bind with.
localaddr=addr
Choose the local IP address. This is useful e.g. if sending
multicast and the host has multiple interfaces, where the user can
choose which interface to send on by specifying the IP address of
that interface.
pkt_size=size
Set the size in bytes of UDP packets.
reuse=1|0
Explicitly allow or disallow reusing UDP sockets.
ttl=ttl
Set the time to live value (for multicast only).
connect=1|0
Initialize the UDP socket with "connect()". In this case, the
destination address can't be changed with ff_udp_set_remote_url
later. If the destination address isn't known at the start, this
option can be specified in ff_udp_set_remote_url, too. This allows
finding out the source address for the packets with getsockname,
and makes writes return with AVERROR(ECONNREFUSED) if "destination
unreachable" is received. For receiving, this gives the benefit of
only receiving packets from the specified peer address/port.
sources=address[,address]
Only receive packets sent to the multicast group from one of the
specified sender IP addresses.
block=address[,address]
Ignore packets sent to the multicast group from the specified
sender IP addresses.
fifo_size=units
Set the UDP receiving circular buffer size, expressed as a number
of packets with size of 188 bytes. If not specified defaults to
7*4096.
overrun_nonfatal=1|0
Survive in case of UDP receiving circular buffer overrun. Default
value is 0.
timeout=microseconds
Set raise error timeout, expressed in microseconds.
This option is only relevant in read mode: if no data arrived in
more than this time interval, raise error.
Examples
· Use ffmpeg to stream over UDP to a remote endpoint:
ffmpeg -i <input> -f <format> udp://<hostname>:<port>
· Use ffmpeg to stream in mpegts format over UDP using 188 sized UDP
packets, using a large input buffer:
ffmpeg -i <input> -f mpegts udp://<hostname>:<port>?pkt_size=188&buffer_size=65535
· Use ffmpeg to receive over UDP from a remote endpoint:
ffmpeg -i udp://[<multicast-address>]:<port> ...
unix
Unix local socket
The required syntax for a Unix socket URL is:
unix://<filepath>
The following parameters can be set via command line options (or in
code via "AVOption"s):
timeout
Timeout in ms.
listen
Create the Unix socket in listening mode.
DEVICE OPTIONS
The libavdevice library provides the same interface as libavformat.
Namely, an input device is considered like a demuxer, and an output
device like a muxer, and the interface and generic device options are
the same provided by libavformat (see the ffmpeg-formats manual).
In addition each input or output device may support so-called private
options, which are specific for that component.
Options may be set by specifying -option value in the FFmpeg tools, or
by setting the value explicitly in the device "AVFormatContext" options
or using the libavutil/opt.h API for programmatic use.
INPUT DEVICES
Input devices are configured elements in FFmpeg which allow to access
the data coming from a multimedia device attached to your system.
When you configure your FFmpeg build, all the supported input devices
are enabled by default. You can list all available ones using the
configure option "--list-indevs".
You can disable all the input devices using the configure option
"--disable-indevs", and selectively enable an input device using the
option "--enable-indev=INDEV", or you can disable a particular input
device using the option "--disable-indev=INDEV".
The option "-formats" of the ff* tools will display the list of
supported input devices (amongst the demuxers).
A description of the currently available input devices follows.
alsa
ALSA (Advanced Linux Sound Architecture) input device.
To enable this input device during configuration you need libasound
installed on your system.
This device allows capturing from an ALSA device. The name of the
device to capture has to be an ALSA card identifier.
An ALSA identifier has the syntax:
hw:<CARD>[,<DEV>[,<SUBDEV>]]
where the DEV and SUBDEV components are optional.
The three arguments (in order: CARD,DEV,SUBDEV) specify card number or
identifier, device number and subdevice number (-1 means any).
To see the list of cards currently recognized by your system check the
files /proc/asound/cards and /proc/asound/devices.
For example to capture with ffmpeg from an ALSA device with card id 0,
you may run the command:
ffmpeg -f alsa -i hw:0 alsaout.wav
For more information see:
<http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html>
bktr
BSD video input device.
dshow
Windows DirectShow input device.
DirectShow support is enabled when FFmpeg is built with the mingw-w64
project. Currently only audio and video devices are supported.
Multiple devices may be opened as separate inputs, but they may also be
opened on the same input, which should improve synchronism between
them.
The input name should be in the format:
<TYPE>=<NAME>[:<TYPE>=<NAME>]
where TYPE can be either audio or video, and NAME is the device's name.
Options
If no options are specified, the device's defaults are used. If the
device does not support the requested options, it will fail to open.
video_size
Set the video size in the captured video.
framerate
Set the frame rate in the captured video.
sample_rate
Set the sample rate (in Hz) of the captured audio.
sample_size
Set the sample size (in bits) of the captured audio.
channels
Set the number of channels in the captured audio.
list_devices
If set to true, print a list of devices and exit.
list_options
If set to true, print a list of selected device's options and exit.
video_device_number
Set video device number for devices with same name (starts at 0,
defaults to 0).
audio_device_number
Set audio device number for devices with same name (starts at 0,
defaults to 0).
pixel_format
Select pixel format to be used by DirectShow. This may only be set
when the video codec is not set or set to rawvideo.
audio_buffer_size
Set audio device buffer size in milliseconds (which can directly
impact latency, depending on the device). Defaults to using the
audio device's default buffer size (typically some multiple of
500ms). Setting this value too low can degrade performance. See
also
<http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx>
Examples
· Print the list of DirectShow supported devices and exit:
$ ffmpeg -list_devices true -f dshow -i dummy
· Open video device Camera:
$ ffmpeg -f dshow -i video="Camera"
· Open second video device with name Camera:
$ ffmpeg -f dshow -video_device_number 1 -i video="Camera"
· Open video device Camera and audio device Microphone:
$ ffmpeg -f dshow -i video="Camera":audio="Microphone"
· Print the list of supported options in selected device and exit:
$ ffmpeg -list_options true -f dshow -i video="Camera"
dv1394
Linux DV 1394 input device.
fbdev
Linux framebuffer input device.
The Linux framebuffer is a graphic hardware-independent abstraction
layer to show graphics on a computer monitor, typically on the console.
It is accessed through a file device node, usually /dev/fb0.
For more detailed information read the file
Documentation/fb/framebuffer.txt included in the Linux source tree.
To record from the framebuffer device /dev/fb0 with ffmpeg:
ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
You can take a single screenshot image with the command:
ffmpeg -f fbdev -frames:v 1 -r 1 -i /dev/fb0 screenshot.jpeg
See also <http://linux-fbdev.sourceforge.net/>, and fbset(1).
iec61883
FireWire DV/HDV input device using libiec61883.
To enable this input device, you need libiec61883, libraw1394 and
libavc1394 installed on your system. Use the configure option
"--enable-libiec61883" to compile with the device enabled.
The iec61883 capture device supports capturing from a video device
connected via IEEE1394 (FireWire), using libiec61883 and the new Linux
FireWire stack (juju). This is the default DV/HDV input method in Linux
Kernel 2.6.37 and later, since the old FireWire stack was removed.
Specify the FireWire port to be used as input file, or "auto" to choose
the first port connected.
Options
dvtype
Override autodetection of DV/HDV. This should only be used if auto
detection does not work, or if usage of a different device type
should be prohibited. Treating a DV device as HDV (or vice versa)
will not work and result in undefined behavior. The values auto,
dv and hdv are supported.
dvbuffer
Set maxiumum size of buffer for incoming data, in frames. For DV,
this is an exact value. For HDV, it is not frame exact, since HDV
does not have a fixed frame size.
dvguid
Select the capture device by specifying it's GUID. Capturing will
only be performed from the specified device and fails if no device
with the given GUID is found. This is useful to select the input if
multiple devices are connected at the same time. Look at
/sys/bus/firewire/devices to find out the GUIDs.
Examples
· Grab and show the input of a FireWire DV/HDV device.
ffplay -f iec61883 -i auto
· Grab and record the input of a FireWire DV/HDV device, using a
packet buffer of 100000 packets if the source is HDV.
ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg
jack
JACK input device.
To enable this input device during configuration you need libjack
installed on your system.
A JACK input device creates one or more JACK writable clients, one for
each audio channel, with name client_name:input_N, where client_name is
the name provided by the application, and N is a number which
identifies the channel. Each writable client will send the acquired
data to the FFmpeg input device.
Once you have created one or more JACK readable clients, you need to
connect them to one or more JACK writable clients.
To connect or disconnect JACK clients you can use the jack_connect and
jack_disconnect programs, or do it through a graphical interface, for
example with qjackctl.
To list the JACK clients and their properties you can invoke the
command jack_lsp.
Follows an example which shows how to capture a JACK readable client
with ffmpeg.
# Create a JACK writable client with name "ffmpeg".
$ ffmpeg -f jack -i ffmpeg -y out.wav
# Start the sample jack_metro readable client.
$ jack_metro -b 120 -d 0.2 -f 4000
# List the current JACK clients.
$ jack_lsp -c
system:capture_1
system:capture_2
system:playback_1
system:playback_2
ffmpeg:input_1
metro:120_bpm
# Connect metro to the ffmpeg writable client.
$ jack_connect metro:120_bpm ffmpeg:input_1
For more information read: <http://jackaudio.org/>
lavfi
Libavfilter input virtual device.
This input device reads data from the open output pads of a libavfilter
filtergraph.
For each filtergraph open output, the input device will create a
corresponding stream which is mapped to the generated output. Currently
only video data is supported. The filtergraph is specified through the
option graph.
Options
graph
Specify the filtergraph to use as input. Each video open output
must be labelled by a unique string of the form "outN", where N is
a number starting from 0 corresponding to the mapped input stream
generated by the device. The first unlabelled output is
automatically assigned to the "out0" label, but all the others need
to be specified explicitly.
If not specified defaults to the filename specified for the input
device.
graph_file
Set the filename of the filtergraph to be read and sent to the
other filters. Syntax of the filtergraph is the same as the one
specified by the option graph.
Examples
· Create a color video stream and play it back with ffplay:
ffplay -f lavfi -graph "color=c=pink [out0]" dummy
· As the previous example, but use filename for specifying the graph
description, and omit the "out0" label:
ffplay -f lavfi color=c=pink
· Create three different video test filtered sources and play them:
ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
· Read an audio stream from a file using the amovie source and play
it back with ffplay:
ffplay -f lavfi "amovie=test.wav"
· Read an audio stream and a video stream and play it back with
ffplay:
ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
libdc1394
IIDC1394 input device, based on libdc1394 and libraw1394.
openal
The OpenAL input device provides audio capture on all systems with a
working OpenAL 1.1 implementation.
To enable this input device during configuration, you need OpenAL
headers and libraries installed on your system, and need to configure
FFmpeg with "--enable-openal".
OpenAL headers and libraries should be provided as part of your OpenAL
implementation, or as an additional download (an SDK). Depending on
your installation you may need to specify additional flags via the
"--extra-cflags" and "--extra-ldflags" for allowing the build system to
locate the OpenAL headers and libraries.
An incomplete list of OpenAL implementations follows:
Creative
The official Windows implementation, providing hardware
acceleration with supported devices and software fallback. See
<http://openal.org/>.
OpenAL Soft
Portable, open source (LGPL) software implementation. Includes
backends for the most common sound APIs on the Windows, Linux,
Solaris, and BSD operating systems. See
<http://kcat.strangesoft.net/openal.html>.
Apple
OpenAL is part of Core Audio, the official Mac OS X Audio
interface. See
<http://developer.apple.com/technologies/mac/audio-and-video.html>
This device allows one to capture from an audio input device handled
through OpenAL.
You need to specify the name of the device to capture in the provided
filename. If the empty string is provided, the device will
automatically select the default device. You can get the list of the
supported devices by using the option list_devices.
Options
channels
Set the number of channels in the captured audio. Only the values 1
(monaural) and 2 (stereo) are currently supported. Defaults to 2.
sample_size
Set the sample size (in bits) of the captured audio. Only the
values 8 and 16 are currently supported. Defaults to 16.
sample_rate
Set the sample rate (in Hz) of the captured audio. Defaults to
44.1k.
list_devices
If set to true, print a list of devices and exit. Defaults to
false.
Examples
Print the list of OpenAL supported devices and exit:
$ ffmpeg -list_devices true -f openal -i dummy out.ogg
Capture from the OpenAL device DR-BT101 via PulseAudio:
$ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
Capture from the default device (note the empty string '' as filename):
$ ffmpeg -f openal -i '' out.ogg
Capture from two devices simultaneously, writing to two different
files, within the same ffmpeg command:
$ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
Note: not all OpenAL implementations support multiple simultaneous
capture - try the latest OpenAL Soft if the above does not work.
oss
Open Sound System input device.
The filename to provide to the input device is the device node
representing the OSS input device, and is usually set to /dev/dsp.
For example to grab from /dev/dsp using ffmpeg use the command:
ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
For more information about OSS see:
<http://manuals.opensound.com/usersguide/dsp.html>
pulse
PulseAudio input device.
To enable this output device you need to configure FFmpeg with
"--enable-libpulse".
The filename to provide to the input device is a source device or the
string "default"
To list the PulseAudio source devices and their properties you can
invoke the command pactl list sources.
More information about PulseAudio can be found on
<http://www.pulseaudio.org>.
Options
server
Connect to a specific PulseAudio server, specified by an IP
address. Default server is used when not provided.
name
Specify the application name PulseAudio will use when showing
active clients, by default it is the "LIBAVFORMAT_IDENT" string.
stream_name
Specify the stream name PulseAudio will use when showing active
streams, by default it is "record".
sample_rate
Specify the samplerate in Hz, by default 48kHz is used.
channels
Specify the channels in use, by default 2 (stereo) is set.
frame_size
Specify the number of bytes per frame, by default it is set to
1024.
fragment_size
Specify the minimal buffering fragment in PulseAudio, it will
affect the audio latency. By default it is unset.
Examples
Record a stream from default device:
ffmpeg -f pulse -i default /tmp/pulse.wav
sndio
sndio input device.
To enable this input device during configuration you need libsndio
installed on your system.
The filename to provide to the input device is the device node
representing the sndio input device, and is usually set to /dev/audio0.
For example to grab from /dev/audio0 using ffmpeg use the command:
ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
video4linux2, v4l2
Video4Linux2 input video device.
"v4l2" can be used as alias for "video4linux2".
If FFmpeg is built with v4l-utils support (by using the
"--enable-libv4l2" configure option), it is possible to use it with the
"-use_libv4l2" input device option.
The name of the device to grab is a file device node, usually Linux
systems tend to automatically create such nodes when the device (e.g.
an USB webcam) is plugged into the system, and has a name of the kind
/dev/videoN, where N is a number associated to the device.
Video4Linux2 devices usually support a limited set of widthxheight
sizes and frame rates. You can check which are supported using
-list_formats all for Video4Linux2 devices. Some devices, like TV
cards, support one or more standards. It is possible to list all the
supported standards using -list_standards all.
The time base for the timestamps is 1 microsecond. Depending on the
kernel version and configuration, the timestamps may be derived from
the real time clock (origin at the Unix Epoch) or the monotonic clock
(origin usually at boot time, unaffected by NTP or manual changes to
the clock). The -timestamps abs or -ts abs option can be used to force
conversion into the real time clock.
Some usage examples of the video4linux2 device with ffmpeg and ffplay:
· Grab and show the input of a video4linux2 device:
ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0
· Grab and record the input of a video4linux2 device, leave the frame
rate and size as previously set:
ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg
For more information about Video4Linux, check <http://linuxtv.org/>.
Options
standard
Set the standard. Must be the name of a supported standard. To get
a list of the supported standards, use the list_standards option.
channel
Set the input channel number. Default to -1, which means using the
previously selected channel.
video_size
Set the video frame size. The argument must be a string in the form
WIDTHxHEIGHT or a valid size abbreviation.
pixel_format
Select the pixel format (only valid for raw video input).
input_format
Set the preferred pixel format (for raw video) or a codec name.
This option allows one to select the input format, when several are
available.
framerate
Set the preferred video frame rate.
list_formats
List available formats (supported pixel formats, codecs, and frame
sizes) and exit.
Available values are:
all Show all available (compressed and non-compressed) formats.
raw Show only raw video (non-compressed) formats.
compressed
Show only compressed formats.
list_standards
List supported standards and exit.
Available values are:
all Show all supported standards.
timestamps, ts
Set type of timestamps for grabbed frames.
Available values are:
default
Use timestamps from the kernel.
abs Use absolute timestamps (wall clock).
mono2abs
Force conversion from monotonic to absolute timestamps.
Default value is "default".
vfwcap
VfW (Video for Windows) capture input device.
The filename passed as input is the capture driver number, ranging from
0 to 9. You may use "list" as filename to print a list of drivers. Any
other filename will be interpreted as device number 0.
x11grab
X11 video input device.
This device allows one to capture a region of an X11 display.
The filename passed as input has the syntax:
[<hostname>]:<display_number>.<screen_number>[+<x_offset>,<y_offset>]
hostname:display_number.screen_number specifies the X11 display name of
the screen to grab from. hostname can be omitted, and defaults to
"localhost". The environment variable DISPLAY contains the default
display name.
x_offset and y_offset specify the offsets of the grabbed area with
respect to the top-left border of the X11 screen. They default to 0.
Check the X11 documentation (e.g. man X) for more detailed information.
Use the dpyinfo program for getting basic information about the
properties of your X11 display (e.g. grep for "name" or "dimensions").
For example to grab from :0.0 using ffmpeg:
ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0 out.mpg
Grab at position "10,20":
ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
Options
draw_mouse
Specify whether to draw the mouse pointer. A value of 0 specify not
to draw the pointer. Default value is 1.
follow_mouse
Make the grabbed area follow the mouse. The argument can be
"centered" or a number of pixels PIXELS.
When it is specified with "centered", the grabbing region follows
the mouse pointer and keeps the pointer at the center of region;
otherwise, the region follows only when the mouse pointer reaches
within PIXELS (greater than zero) to the edge of region.
For example:
ffmpeg -f x11grab -follow_mouse centered -framerate 25 -video_size cif -i :0.0 out.mpg
To follow only when the mouse pointer reaches within 100 pixels to
edge:
ffmpeg -f x11grab -follow_mouse 100 -framerate 25 -video_size cif -i :0.0 out.mpg
framerate
Set the grabbing frame rate. Default value is "ntsc", corresponding
to a frame rate of "30000/1001".
show_region
Show grabbed region on screen.
If show_region is specified with 1, then the grabbing region will
be indicated on screen. With this option, it is easy to know what
is being grabbed if only a portion of the screen is grabbed.
For example:
ffmpeg -f x11grab -show_region 1 -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
With follow_mouse:
ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
video_size
Set the video frame size. Default value is "vga".
RESAMPLER OPTIONS
The audio resampler supports the following named options.
Options may be set by specifying -option value in the FFmpeg tools,
option=value for the aresample filter, by setting the value explicitly
in the "SwrContext" options or using the libavutil/opt.h API for
programmatic use.
ich, in_channel_count
Set the number of input channels. Default value is 0. Setting this
value is not mandatory if the corresponding channel layout
in_channel_layout is set.
och, out_channel_count
Set the number of output channels. Default value is 0. Setting this
value is not mandatory if the corresponding channel layout
out_channel_layout is set.
uch, used_channel_count
Set the number of used input channels. Default value is 0. This
option is only used for special remapping.
isr, in_sample_rate
Set the input sample rate. Default value is 0.
osr, out_sample_rate
Set the output sample rate. Default value is 0.
isf, in_sample_fmt
Specify the input sample format. It is set by default to "none".
osf, out_sample_fmt
Specify the output sample format. It is set by default to "none".
tsf, internal_sample_fmt
Set the internal sample format. Default value is "none". This will
automatically be chosen when it is not explicitly set.
icl, in_channel_layout
ocl, out_channel_layout
Set the input/output channel layout.
See the Channel Layout section in the ffmpeg-utils(1) manual for
the required syntax.
clev, center_mix_level
Set the center mix level. It is a value expressed in deciBel, and
must be in the interval [-32,32].
slev, surround_mix_level
Set the surround mix level. It is a value expressed in deciBel, and
must be in the interval [-32,32].
lfe_mix_level
Set LFE mix into non LFE level. It is used when there is a LFE
input but no LFE output. It is a value expressed in deciBel, and
must be in the interval [-32,32].
rmvol, rematrix_volume
Set rematrix volume. Default value is 1.0.
rematrix_maxval
Set maximum output value for rematrixing. This can be used to
prevent clipping vs. preventing volumn reduction A value of 1.0
prevents cliping.
flags, swr_flags
Set flags used by the converter. Default value is 0.
It supports the following individual flags:
res force resampling, this flag forces resampling to be used even
when the input and output sample rates match.
dither_scale
Set the dither scale. Default value is 1.
dither_method
Set dither method. Default value is 0.
Supported values:
rectangular
select rectangular dither
triangular
select triangular dither
triangular_hp
select triangular dither with high pass
lipshitz
select lipshitz noise shaping dither
shibata
select shibata noise shaping dither
low_shibata
select low shibata noise shaping dither
high_shibata
select high shibata noise shaping dither
f_weighted
select f-weighted noise shaping dither
modified_e_weighted
select modified-e-weighted noise shaping dither
improved_e_weighted
select improved-e-weighted noise shaping dither
resampler
Set resampling engine. Default value is swr.
Supported values:
swr select the native SW Resampler; filter options precision and
cheby are not applicable in this case.
soxr
select the SoX Resampler (where available); compensation, and
filter options filter_size, phase_shift, filter_type &
kaiser_beta, are not applicable in this case.
filter_size
For swr only, set resampling filter size, default value is 32.
phase_shift
For swr only, set resampling phase shift, default value is 10, and
must be in the interval [0,30].
linear_interp
Use Linear Interpolation if set to 1, default value is 0.
cutoff
Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must
be a float value between 0 and 1. Default value is 0.97 with swr,
and 0.91 with soxr (which, with a sample-rate of 44100, preserves
the entire audio band to 20kHz).
precision
For soxr only, the precision in bits to which the resampled signal
will be calculated. The default value of 20 (which, with suitable
dithering, is appropriate for a destination bit-depth of 16) gives
SoX's 'High Quality'; a value of 28 gives SoX's 'Very High
Quality'.
cheby
For soxr only, selects passband rolloff none (Chebyshev) & higher-
precision approximation for 'irrational' ratios. Default value is
0.
async
For swr only, simple 1 parameter audio sync to timestamps using
stretching, squeezing, filling and trimming. Setting this to 1 will
enable filling and trimming, larger values represent the maximum
amount in samples that the data may be stretched or squeezed for
each second. Default value is 0, thus no compensation is applied
to make the samples match the audio timestamps.
first_pts
For swr only, assume the first pts should be this value. The time
unit is 1 / sample rate. This allows for padding/trimming at the
start of stream. By default, no assumption is made about the first
frame's expected pts, so no padding or trimming is done. For
example, this could be set to 0 to pad the beginning with silence
if an audio stream starts after the video stream or to trim any
samples with a negative pts due to encoder delay.
min_comp
For swr only, set the minimum difference between timestamps and
audio data (in seconds) to trigger stretching/squeezing/filling or
trimming of the data to make it match the timestamps. The default
is that stretching/squeezing/filling and trimming is disabled
(min_comp = "FLT_MAX").
min_hard_comp
For swr only, set the minimum difference between timestamps and
audio data (in seconds) to trigger adding/dropping samples to make
it match the timestamps. This option effectively is a threshold to
select between hard (trim/fill) and soft (squeeze/stretch)
compensation. Note that all compensation is by default disabled
through min_comp. The default is 0.1.
comp_duration
For swr only, set duration (in seconds) over which data is
stretched/squeezed to make it match the timestamps. Must be a non-
negative double float value, default value is 1.0.
max_soft_comp
For swr only, set maximum factor by which data is
stretched/squeezed to make it match the timestamps. Must be a non-
negative double float value, default value is 0.
matrix_encoding
Select matrixed stereo encoding.
It accepts the following values:
none
select none
dolby
select Dolby
dplii
select Dolby Pro Logic II
Default value is "none".
filter_type
For swr only, select resampling filter type. This only affects
resampling operations.
It accepts the following values:
cubic
select cubic
blackman_nuttall
select Blackman Nuttall Windowed Sinc
kaiser
select Kaiser Windowed Sinc
kaiser_beta
For swr only, set Kaiser Window Beta value. Must be an integer in
the interval [2,16], default value is 9.
output_sample_bits
For swr only, set number of used output sample bits for dithering.
Must be an integer in the interval [0,64], default value is 0,
which means it's not used.
SCALER OPTIONS
The video scaler supports the following named options.
Options may be set by specifying -option value in the FFmpeg tools. For
programmatic use, they can be set explicitly in the "SwsContext"
options or through the libavutil/opt.h API.
sws_flags
Set the scaler flags. This is also used to set the scaling
algorithm. Only a single algorithm should be selected.
It accepts the following values:
fast_bilinear
Select fast bilinear scaling algorithm.
bilinear
Select bilinear scaling algorithm.
bicubic
Select bicubic scaling algorithm.
experimental
Select experimental scaling algorithm.
neighbor
Select nearest neighbor rescaling algorithm.
area
Select averaging area rescaling algorithm.
bicublin
Select bicubic scaling algorithm for the luma component,
bilinear for chroma components.
gauss
Select Gaussian rescaling algorithm.
sinc
Select sinc rescaling algorithm.
lanczos
Select lanczos rescaling algorithm.
spline
Select natural bicubic spline rescaling algorithm.
print_info
Enable printing/debug logging.
accurate_rnd
Enable accurate rounding.
full_chroma_int
Enable full chroma interpolation.
full_chroma_inp
Select full chroma input.
bitexact
Enable bitexact output.
srcw
Set source width.
srch
Set source height.
dstw
Set destination width.
dsth
Set destination height.
src_format
Set source pixel format (must be expressed as an integer).
dst_format
Set destination pixel format (must be expressed as an integer).
src_range
Select source range.
dst_range
Select destination range.
param0, param1
Set scaling algorithm parameters. The specified values are specific
of some scaling algorithms and ignored by others. The specified
values are floating point number values.
sws_dither
Set the dithering algorithm. Accepts one of the following values.
Default value is auto.
auto
automatic choice
none
no dithering
bayer
bayer dither
ed error diffusion dither
FILTERING INTRODUCTION
Filtering in FFmpeg is enabled through the libavfilter library.
In libavfilter, a filter can have multiple inputs and multiple outputs.
To illustrate the sorts of things that are possible, we consider the
following filtergraph.
[main]
input --> split ---------------------> overlay --> output
| ^
|[tmp] [flip]|
+-----> crop --> vflip -------+
This filtergraph splits the input stream in two streams, sends one
stream through the crop filter and the vflip filter before merging it
back with the other stream by overlaying it on top. You can use the
following command to achieve this:
ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
The result will be that in output the top half of the video is mirrored
onto the bottom half.
Filters in the same linear chain are separated by commas, and distinct
linear chains of filters are separated by semicolons. In our example,
crop,vflip are in one linear chain, split and overlay are separately in
another. The points where the linear chains join are labelled by names
enclosed in square brackets. In the example, the split filter generates
two outputs that are associated to the labels [main] and [tmp].
The stream sent to the second output of split, labelled as [tmp], is
processed through the crop filter, which crops away the lower half part
of the video, and then vertically flipped. The overlay filter takes in
input the first unchanged output of the split filter (which was
labelled as [main]), and overlay on its lower half the output generated
by the crop,vflip filterchain.
Some filters take in input a list of parameters: they are specified
after the filter name and an equal sign, and are separated from each
other by a colon.
There exist so-called source filters that do not have an audio/video
input, and sink filters that will not have audio/video output.
GRAPH
The graph2dot program included in the FFmpeg tools directory can be
used to parse a filtergraph description and issue a corresponding
textual representation in the dot language.
Invoke the command:
graph2dot -h
to see how to use graph2dot.
You can then pass the dot description to the dot program (from the
graphviz suite of programs) and obtain a graphical representation of
the filtergraph.
For example the sequence of commands:
echo <GRAPH_DESCRIPTION> | \
tools/graph2dot -o graph.tmp && \
dot -Tpng graph.tmp -o graph.png && \
display graph.png
can be used to create and display an image representing the graph
described by the GRAPH_DESCRIPTION string. Note that this string must
be a complete self-contained graph, with its inputs and outputs
explicitly defined. For example if your command line is of the form:
ffmpeg -i infile -vf scale=640:360 outfile
your GRAPH_DESCRIPTION string will need to be of the form:
nullsrc,scale=640:360,nullsink
you may also need to set the nullsrc parameters and add a format filter
in order to simulate a specific input file.
FILTERGRAPH DESCRIPTION
A filtergraph is a directed graph of connected filters. It can contain
cycles, and there can be multiple links between a pair of filters. Each
link has one input pad on one side connecting it to one filter from
which it takes its input, and one output pad on the other side
connecting it to the one filter accepting its output.
Each filter in a filtergraph is an instance of a filter class
registered in the application, which defines the features and the
number of input and output pads of the filter.
A filter with no input pads is called a "source", a filter with no
output pads is called a "sink".
Filtergraph syntax
A filtergraph can be represented using a textual representation, which
is recognized by the -filter/-vf and -filter_complex options in ffmpeg
and -vf in ffplay, and by the
"avfilter_graph_parse()"/"avfilter_graph_parse2()" function defined in
libavfilter/avfilter.h.
A filterchain consists of a sequence of connected filters, each one
connected to the previous one in the sequence. A filterchain is
represented by a list of ","-separated filter descriptions.
A filtergraph consists of a sequence of filterchains. A sequence of
filterchains is represented by a list of ";"-separated filterchain
descriptions.
A filter is represented by a string of the form:
[in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]
filter_name is the name of the filter class of which the described
filter is an instance of, and has to be the name of one of the filter
classes registered in the program. The name of the filter class is
optionally followed by a string "=arguments".
arguments is a string which contains the parameters used to initialize
the filter instance. It may have one of the following forms:
· A ':'-separated list of key=value pairs.
· A ':'-separated list of value. In this case, the keys are assumed
to be the option names in the order they are declared. E.g. the
"fade" filter declares three options in this order -- type,
start_frame and nb_frames. Then the parameter list in:0:30 means
that the value in is assigned to the option type, 0 to start_frame
and 30 to nb_frames.
· A ':'-separated list of mixed direct value and long key=value
pairs. The direct value must precede the key=value pairs, and
follow the same constraints order of the previous point. The
following key=value pairs can be set in any preferred order.
If the option value itself is a list of items (e.g. the "format" filter
takes a list of pixel formats), the items in the list are usually
separated by '|'.
The list of arguments can be quoted using the character "'" as initial
and ending mark, and the character '\' for escaping the characters
within the quoted text; otherwise the argument string is considered
terminated when the next special character (belonging to the set
"[]=;,") is encountered.
The name and arguments of the filter are optionally preceded and
followed by a list of link labels. A link label allows one to name a
link and associate it to a filter output or input pad. The preceding
labels in_link_1 ... in_link_N, are associated to the filter input
pads, the following labels out_link_1 ... out_link_M, are associated to
the output pads.
When two link labels with the same name are found in the filtergraph, a
link between the corresponding input and output pad is created.
If an output pad is not labelled, it is linked by default to the first
unlabelled input pad of the next filter in the filterchain. For
example in the filterchain:
nullsrc, split[L1], [L2]overlay, nullsink
the split filter instance has two output pads, and the overlay filter
instance two input pads. The first output pad of split is labelled
"L1", the first input pad of overlay is labelled "L2", and the second
output pad of split is linked to the second input pad of overlay, which
are both unlabelled.
In a complete filterchain all the unlabelled filter input and output
pads must be connected. A filtergraph is considered valid if all the
filter input and output pads of all the filterchains are connected.
Libavfilter will automatically insert scale filters where format
conversion is required. It is possible to specify swscale flags for
those automatically inserted scalers by prepending "sws_flags=flags;"
to the filtergraph description.
Follows a BNF description for the filtergraph syntax:
<NAME> ::= sequence of alphanumeric characters and '_'
<LINKLABEL> ::= "[" <NAME> "]"
<LINKLABELS> ::= <LINKLABEL> [<LINKLABELS>]
<FILTER_ARGUMENTS> ::= sequence of chars (eventually quoted)
<FILTER> ::= [<LINKLABELS>] <NAME> ["=" <FILTER_ARGUMENTS>] [<LINKLABELS>]
<FILTERCHAIN> ::= <FILTER> [,<FILTERCHAIN>]
<FILTERGRAPH> ::= [sws_flags=<flags>;] <FILTERCHAIN> [;<FILTERGRAPH>]
Notes on filtergraph escaping
Filtergraph description composition entails several levels of escaping.
See the "Quoting and escaping" section in the ffmpeg-utils(1) manual
for more information about the employed escaping procedure.
A first level escaping affects the content of each filter option value,
which may contain the special character ":" used to separate values, or
one of the escaping characters "\'".
A second level escaping affects the whole filter description, which may
contain the escaping characters "\'" or the special characters "[],;"
used by the filtergraph description.
Finally, when you specify a filtergraph on a shell commandline, you
need to perform a third level escaping for the shell special characters
contained within it.
For example, consider the following string to be embedded in the
drawtext filter description text value:
this is a 'string': may contain one, or more, special characters
This string contains the "'" special escaping character, and the ":"
special character, so it needs to be escaped in this way:
text=this is a \'string\'\: may contain one, or more, special characters
A second level of escaping is required when embedding the filter
description in a filtergraph description, in order to escape all the
filtergraph special characters. Thus the example above becomes:
drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
(note that in addition to the "\'" escaping special characters, also
"," needs to be escaped).
Finally an additional level of escaping is needed when writing the
filtergraph description in a shell command, which depends on the
escaping rules of the adopted shell. For example, assuming that "\" is
special and needs to be escaped with another "\", the previous string
will finally result in:
-vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
TIMELINE EDITING
Some filters support a generic enable option. For the filters
supporting timeline editing, this option can be set to an expression
which is evaluated before sending a frame to the filter. If the
evaluation is non-zero, the filter will be enabled, otherwise the frame
will be sent unchanged to the next filter in the filtergraph.
The expression accepts the following values:
t timestamp expressed in seconds, NAN if the input timestamp is
unknown
n sequential number of the input frame, starting from 0
pos the position in the file of the input frame, NAN if unknown
Additionally, these filters support an enable command that can be used
to re-define the expression.
Like any other filtering option, the enable option follows the same
rules.
For example, to enable a blur filter (smartblur) from 10 seconds to 3
minutes, and a curves filter starting at 3 seconds:
smartblur = enable='between(t,10,3*60)',
curves = enable='gte(t,3)' : preset=cross_process
AUDIO FILTERS
When you configure your FFmpeg build, you can disable any of the
existing filters using "--disable-filters". The configure output will
show the audio filters included in your build.
Below is a description of the currently available audio filters.
aconvert
Convert the input audio format to the specified formats.
This filter is deprecated. Use aformat instead.
The filter accepts a string of the form:
"sample_format:channel_layout".
sample_format specifies the sample format, and can be a string or the
corresponding numeric value defined in libavutil/samplefmt.h. Use 'p'
suffix for a planar sample format.
channel_layout specifies the channel layout, and can be a string or the
corresponding number value defined in libavutil/channel_layout.h.
The special parameter "auto", signifies that the filter will
automatically select the output format depending on the output filter.
Examples
· Convert input to float, planar, stereo:
aconvert=fltp:stereo
· Convert input to unsigned 8-bit, automatically select out channel
layout:
aconvert=u8:auto
adelay
Delay one or more audio channels.
Samples in delayed channel are filled with silence.
The filter accepts the following option:
delays
Set list of delays in milliseconds for each channel separated by
'|'. At least one delay greater than 0 should be provided. Unused
delays will be silently ignored. If number of given delays is
smaller than number of channels all remaining channels will not be
delayed.
Examples
· Delay first channel by 1.5 seconds, the third channel by 0.5
seconds and leave the second channel (and any other channels that
may be present) unchanged.
adelay=1500|0|500
aecho
Apply echoing to the input audio.
Echoes are reflected sound and can occur naturally amongst mountains
(and sometimes large buildings) when talking or shouting; digital echo
effects emulate this behaviour and are often used to help fill out the
sound of a single instrument or vocal. The time difference between the
original signal and the reflection is the "delay", and the loudness of
the reflected signal is the "decay". Multiple echoes can have
different delays and decays.
A description of the accepted parameters follows.
in_gain
Set input gain of reflected signal. Default is 0.6.
out_gain
Set output gain of reflected signal. Default is 0.3.
delays
Set list of time intervals in milliseconds between original signal
and reflections separated by '|'. Allowed range for each "delay" is
"(0 - 90000.0]". Default is 1000.
decays
Set list of loudnesses of reflected signals separated by '|'.
Allowed range for each "decay" is "(0 - 1.0]". Default is 0.5.
Examples
· Make it sound as if there are twice as many instruments as are
actually playing:
aecho=0.8:0.88:60:0.4
· If delay is very short, then it sound like a (metallic) robot
playing music:
aecho=0.8:0.88:6:0.4
· A longer delay will sound like an open air concert in the
mountains:
aecho=0.8:0.9:1000:0.3
· Same as above but with one more mountain:
aecho=0.8:0.9:1000|1800:0.3|0.25
aeval
Modify an audio signal according to the specified expressions.
This filter accepts one or more expressions (one for each channel),
which are evaluated and used to modify a corresponding audio signal.
This filter accepts the following options:
exprs
Set the '|'-separated expressions list for each separate channel.
If the number of input channels is greater than the number of
expressions, the last specified expression is used for the
remaining output channels.
channel_layout, c
Set output channel layout. If not specified, the channel layout is
specified by the number of expressions. If set to same, it will use
by default the same input channel layout.
Each expression in exprs can contain the following constants and
functions:
ch channel number of the current expression
n number of the evaluated sample, starting from 0
s sample rate
t time of the evaluated sample expressed in seconds
nb_in_channels
nb_out_channels
input and output number of channels
val(CH)
the value of input channel with number CH
Note: this filter is slow. For faster processing you should use a
dedicated filter.
Examples
· Half volume:
aeval=val(ch)/2:c=same
· Invert phase of the second channel:
eval=val(0)|-val(1)
afade
Apply fade-in/out effect to input audio.
A description of the accepted parameters follows.
type, t
Specify the effect type, can be either "in" for fade-in, or "out"
for a fade-out effect. Default is "in".
start_sample, ss
Specify the number of the start sample for starting to apply the
fade effect. Default is 0.
nb_samples, ns
Specify the number of samples for which the fade effect has to
last. At the end of the fade-in effect the output audio will have
the same volume as the input audio, at the end of the fade-out
transition the output audio will be silence. Default is 44100.
start_time, st
Specify time for starting to apply the fade effect. Default is 0.
The accepted syntax is:
[-]HH[:MM[:SS[.m...]]]
[-]S+[.m...]
See also the function "av_parse_time()". If set this option is
used instead of start_sample one.
duration, d
Specify the duration for which the fade effect has to last. Default
is 0. The accepted syntax is:
[-]HH[:MM[:SS[.m...]]]
[-]S+[.m...]
See also the function "av_parse_time()". At the end of the fade-in
effect the output audio will have the same volume as the input
audio, at the end of the fade-out transition the output audio will
be silence. If set this option is used instead of nb_samples one.
curve
Set curve for fade transition.
It accepts the following values:
tri select triangular, linear slope (default)
qsin
select quarter of sine wave
hsin
select half of sine wave
esin
select exponential sine wave
log select logarithmic
par select inverted parabola
qua select quadratic
cub select cubic
squ select square root
cbr select cubic root
Examples
· Fade in first 15 seconds of audio:
afade=t=in:ss=0:d=15
· Fade out last 25 seconds of a 900 seconds audio:
afade=t=out:st=875:d=25
aformat
Set output format constraints for the input audio. The framework will
negotiate the most appropriate format to minimize conversions.
The filter accepts the following named parameters:
sample_fmts
A '|'-separated list of requested sample formats.
sample_rates
A '|'-separated list of requested sample rates.
channel_layouts
A '|'-separated list of requested channel layouts.
See the Channel Layout section in the ffmpeg-utils(1) manual for
the required syntax.
If a parameter is omitted, all values are allowed.
For example to force the output to either unsigned 8-bit or signed
16-bit stereo:
aformat=sample_fmts=u8|s16:channel_layouts=stereo
allpass
Apply a two-pole all-pass filter with central frequency (in Hz)
frequency, and filter-width width. An all-pass filter changes the
audio's frequency to phase relationship without changing its frequency
to amplitude relationship.
The filter accepts the following options:
frequency, f
Set frequency in Hz.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Specify the band-width of a filter in width_type units.
amerge
Merge two or more audio streams into a single multi-channel stream.
The filter accepts the following options:
inputs
Set the number of inputs. Default is 2.
If the channel layouts of the inputs are disjoint, and therefore
compatible, the channel layout of the output will be set accordingly
and the channels will be reordered as necessary. If the channel layouts
of the inputs are not disjoint, the output will have all the channels
of the first input then all the channels of the second input, in that
order, and the channel layout of the output will be the default value
corresponding to the total number of channels.
For example, if the first input is in 2.1 (FL+FR+LF) and the second
input is FC+BL+BR, then the output will be in 5.1, with the channels in
the following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of
the first input, b1 is the first channel of the second input).
On the other hand, if both input are in stereo, the output channels
will be in the default order: a1, a2, b1, b2, and the channel layout
will be arbitrarily set to 4.0, which may or may not be the expected
value.
All inputs must have the same sample rate, and format.
If inputs do not have the same duration, the output will stop with the
shortest.
Examples
· Merge two mono files into a stereo stream:
amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
· Multiple merges assuming 1 video stream and 6 audio streams in
input.mkv:
ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
amix
Mixes multiple audio inputs into a single output.
For example
ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
will mix 3 input audio streams to a single output with the same
duration as the first input and a dropout transition time of 3 seconds.
The filter accepts the following named parameters:
inputs
Number of inputs. If unspecified, it defaults to 2.
duration
How to determine the end-of-stream.
longest
Duration of longest input. (default)
shortest
Duration of shortest input.
first
Duration of first input.
dropout_transition
Transition time, in seconds, for volume renormalization when an
input stream ends. The default value is 2 seconds.
anull
Pass the audio source unchanged to the output.
apad
Pad the end of a audio stream with silence, this can be used together
with -shortest to extend audio streams to the same length as the video
stream.
aphaser
Add a phasing effect to the input audio.
A phaser filter creates series of peaks and troughs in the frequency
spectrum. The position of the peaks and troughs are modulated so that
they vary over time, creating a sweeping effect.
A description of the accepted parameters follows.
in_gain
Set input gain. Default is 0.4.
out_gain
Set output gain. Default is 0.74
delay
Set delay in milliseconds. Default is 3.0.
decay
Set decay. Default is 0.4.
speed
Set modulation speed in Hz. Default is 0.5.
type
Set modulation type. Default is triangular.
It accepts the following values:
triangular, t
sinusoidal, s
aresample
Resample the input audio to the specified parameters, using the
libswresample library. If none are specified then the filter will
automatically convert between its input and output.
This filter is also able to stretch/squeeze the audio data to make it
match the timestamps or to inject silence / cut out audio to make it
match the timestamps, do a combination of both or do neither.
The filter accepts the syntax [sample_rate:]resampler_options, where
sample_rate expresses a sample rate and resampler_options is a list of
key=value pairs, separated by ":". See the ffmpeg-resampler manual for
the complete list of supported options.
Examples
· Resample the input audio to 44100Hz:
aresample=44100
· Stretch/squeeze samples to the given timestamps, with a maximum of
1000 samples per second compensation:
aresample=async=1000
asetnsamples
Set the number of samples per each output audio frame.
The last output packet may contain a different number of samples, as
the filter will flush all the remaining samples when the input audio
signal its end.
The filter accepts the following options:
nb_out_samples, n
Set the number of frames per each output audio frame. The number is
intended as the number of samples per each channel. Default value
is 1024.
pad, p
If set to 1, the filter will pad the last audio frame with zeroes,
so that the last frame will contain the same number of samples as
the previous ones. Default value is 1.
For example, to set the number of per-frame samples to 1234 and disable
padding for the last frame, use:
asetnsamples=n=1234:p=0
asetrate
Set the sample rate without altering the PCM data. This will result in
a change of speed and pitch.
The filter accepts the following options:
sample_rate, r
Set the output sample rate. Default is 44100 Hz.
ashowinfo
Show a line containing various information for each input audio frame.
The input audio is not modified.
The shown line contains a sequence of key/value pairs of the form
key:value.
A description of each shown parameter follows:
n sequential number of the input frame, starting from 0
pts Presentation timestamp of the input frame, in time base units; the
time base depends on the filter input pad, and is usually
1/sample_rate.
pts_time
presentation timestamp of the input frame in seconds
pos position of the frame in the input stream, -1 if this information
in unavailable and/or meaningless (for example in case of synthetic
audio)
fmt sample format
chlayout
channel layout
rate
sample rate for the audio frame
nb_samples
number of samples (per channel) in the frame
checksum
Adler-32 checksum (printed in hexadecimal) of the audio data. For
planar audio the data is treated as if all the planes were
concatenated.
plane_checksums
A list of Adler-32 checksums for each data plane.
astats
Display time domain statistical information about the audio channels.
Statistics are calculated and displayed for each audio channel and,
where applicable, an overall figure is also given.
The filter accepts the following option:
length
Short window length in seconds, used for peak and trough RMS
measurement. Default is 0.05 (50 miliseconds). Allowed range is
"[0.1 - 10]".
A description of each shown parameter follows:
DC offset
Mean amplitude displacement from zero.
Min level
Minimal sample level.
Max level
Maximal sample level.
Peak level dB
RMS level dB
Standard peak and RMS level measured in dBFS.
RMS peak dB
RMS trough dB
Peak and trough values for RMS level measured over a short window.
Crest factor
Standard ratio of peak to RMS level (note: not in dB).
Flat factor
Flatness (i.e. consecutive samples with the same value) of the
signal at its peak levels (i.e. either Min level or Max level).
Peak count
Number of occasions (not the number of samples) that the signal
attained either Min level or Max level.
astreamsync
Forward two audio streams and control the order the buffers are
forwarded.
The filter accepts the following options:
expr, e
Set the expression deciding which stream should be forwarded next:
if the result is negative, the first stream is forwarded; if the
result is positive or zero, the second stream is forwarded. It can
use the following variables:
b1 b2
number of buffers forwarded so far on each stream
s1 s2
number of samples forwarded so far on each stream
t1 t2
current timestamp of each stream
The default value is "t1-t2", which means to always forward the
stream that has a smaller timestamp.
Examples
Stress-test "amerge" by randomly sending buffers on the wrong input,
while avoiding too much of a desynchronization:
amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
[a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
[a2] [b2] amerge
asyncts
Synchronize audio data with timestamps by squeezing/stretching it
and/or dropping samples/adding silence when needed.
This filter is not built by default, please use aresample to do
squeezing/stretching.
The filter accepts the following named parameters:
compensate
Enable stretching/squeezing the data to make it match the
timestamps. Disabled by default. When disabled, time gaps are
covered with silence.
min_delta
Minimum difference between timestamps and audio data (in seconds)
to trigger adding/dropping samples. Default value is 0.1. If you
get non-perfect sync with this filter, try setting this parameter
to 0.
max_comp
Maximum compensation in samples per second. Relevant only with
compensate=1. Default value 500.
first_pts
Assume the first pts should be this value. The time base is 1 /
sample rate. This allows for padding/trimming at the start of
stream. By default, no assumption is made about the first frame's
expected pts, so no padding or trimming is done. For example, this
could be set to 0 to pad the beginning with silence if an audio
stream starts after the video stream or to trim any samples with a
negative pts due to encoder delay.
atempo
Adjust audio tempo.
The filter accepts exactly one parameter, the audio tempo. If not
specified then the filter will assume nominal 1.0 tempo. Tempo must be
in the [0.5, 2.0] range.
Examples
· Slow down audio to 80% tempo:
atempo=0.8
· To speed up audio to 125% tempo:
atempo=1.25
atrim
Trim the input so that the output contains one continuous subpart of
the input.
This filter accepts the following options:
start
Specify time of the start of the kept section, i.e. the audio
sample with the timestamp start will be the first sample in the
output.
end Specify time of the first audio sample that will be dropped, i.e.
the audio sample immediately preceding the one with the timestamp
end will be the last sample in the output.
start_pts
Same as start, except this option sets the start timestamp in
samples instead of seconds.
end_pts
Same as end, except this option sets the end timestamp in samples
instead of seconds.
duration
Specify maximum duration of the output.
start_sample
Number of the first sample that should be passed to output.
end_sample
Number of the first sample that should be dropped.
start, end, duration are expressed as time duration specifications,
check the "Time duration" section in the ffmpeg-utils manual.
Note that the first two sets of the start/end options and the duration
option look at the frame timestamp, while the _sample options simply
count the samples that pass through the filter. So start/end_pts and
start/end_sample will give different results when the timestamps are
wrong, inexact or do not start at zero. Also note that this filter does
not modify the timestamps. If you wish that the output timestamps start
at zero, insert the asetpts filter after the atrim filter.
If multiple start or end options are set, this filter tries to be
greedy and keep all samples that match at least one of the specified
constraints. To keep only the part that matches all the constraints at
once, chain multiple atrim filters.
The defaults are such that all the input is kept. So it is possible to
set e.g. just the end values to keep everything before the specified
time.
Examples:
· drop everything except the second minute of input
ffmpeg -i INPUT -af atrim=60:120
· keep only the first 1000 samples
ffmpeg -i INPUT -af atrim=end_sample=1000
bandpass
Apply a two-pole Butterworth band-pass filter with central frequency
frequency, and (3dB-point) band-width width. The csg option selects a
constant skirt gain (peak gain = Q) instead of the default: constant
0dB peak gain. The filter roll off at 6dB per octave (20dB per
decade).
The filter accepts the following options:
frequency, f
Set the filter's central frequency. Default is 3000.
csg Constant skirt gain if set to 1. Defaults to 0.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Specify the band-width of a filter in width_type units.
bandreject
Apply a two-pole Butterworth band-reject filter with central frequency
frequency, and (3dB-point) band-width width. The filter roll off at
6dB per octave (20dB per decade).
The filter accepts the following options:
frequency, f
Set the filter's central frequency. Default is 3000.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Specify the band-width of a filter in width_type units.
bass
Boost or cut the bass (lower) frequencies of the audio using a two-pole
shelving filter with a response similar to that of a standard hi-fi's
tone-controls. This is also known as shelving equalisation (EQ).
The filter accepts the following options:
gain, g
Give the gain at 0 Hz. Its useful range is about -20 (for a large
cut) to +20 (for a large boost). Beware of clipping when using a
positive gain.
frequency, f
Set the filter's central frequency and so can be used to extend or
reduce the frequency range to be boosted or cut. The default value
is 100 Hz.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Determine how steep is the filter's shelf transition.
biquad
Apply a biquad IIR filter with the given coefficients. Where b0, b1,
b2 and a0, a1, a2 are the numerator and denominator coefficients
respectively.
channelmap
Remap input channels to new locations.
This filter accepts the following named parameters:
channel_layout
Channel layout of the output stream.
map Map channels from input to output. The argument is a '|'-separated
list of mappings, each in the "in_channel-out_channel" or
in_channel form. in_channel can be either the name of the input
channel (e.g. FL for front left) or its index in the input channel
layout. out_channel is the name of the output channel or its index
in the output channel layout. If out_channel is not given then it
is implicitly an index, starting with zero and increasing by one
for each mapping.
If no mapping is present, the filter will implicitly map input channels
to output channels preserving index.
For example, assuming a 5.1+downmix input MOV file
ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
will create an output WAV file tagged as stereo from the downmix
channels of the input.
To fix a 5.1 WAV improperly encoded in AAC's native channel order
ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
channelsplit
Split each channel in input audio stream into a separate output stream.
This filter accepts the following named parameters:
channel_layout
Channel layout of the input stream. Default is "stereo".
For example, assuming a stereo input MP3 file
ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
will create an output Matroska file with two audio streams, one
containing only the left channel and the other the right channel.
To split a 5.1 WAV file into per-channel files
ffmpeg -i in.wav -filter_complex
'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
-map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
side_right.wav
compand
Compress or expand audio dynamic range.
A description of the accepted options follows.
attacks
decays
Set list of times in seconds for each channel over which the
instantaneous level of the input signal is averaged to determine
its volume. attacks refers to increase of volume and decays refers
to decrease of volume. For most situations, the attack time
(response to the audio getting louder) should be shorter than the
decay time because the human ear is more sensitive to sudden loud
audio than sudden soft audio. A typical value for attack is 0.3
seconds and a typical value for decay is 0.8 seconds.
points
Set list of points for the transfer function, specified in dB
relative to the maximum possible signal amplitude. Each key points
list must be defined using the following syntax:
"x0/y0|x1/y1|x2/y2|...." or "x0/y0 x1/y1 x2/y2 ...."
The input values must be in strictly increasing order but the
transfer function does not have to be monotonically rising. The
point "0/0" is assumed but may be overridden (by "0/out-dBn").
Typical values for the transfer function are "-70/-70|-60/-20".
soft-knee
Set the curve radius in dB for all joints. Defaults to 0.01.
gain
Set additional gain in dB to be applied at all points on the
transfer function. This allows easy adjustment of the overall
gain. Defaults to 0.
volume
Set initial volume in dB to be assumed for each channel when
filtering starts. This permits the user to supply a nominal level
initially, so that, for example, a very large gain is not applied
to initial signal levels before the companding has begun to
operate. A typical value for audio which is initially quiet is -90
dB. Defaults to 0.
delay
Set delay in seconds. The input audio is analyzed immediately, but
audio is delayed before being fed to the volume adjuster.
Specifying a delay approximately equal to the attack/decay times
allows the filter to effectively operate in predictive rather than
reactive mode. Defaults to 0.
Examples
· Make music with both quiet and loud passages suitable for listening
in a noisy environment:
compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
· Noise gate for when the noise is at a lower level than the signal:
compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
· Here is another noise gate, this time for when the noise is at a
higher level than the signal (making it, in some ways, similar to
squelch):
compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
earwax
Make audio easier to listen to on headphones.
This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
so that when listened to on headphones the stereo image is moved from
inside your head (standard for headphones) to outside and in front of
the listener (standard for speakers).
Ported from SoX.
equalizer
Apply a two-pole peaking equalisation (EQ) filter. With this filter,
the signal-level at and around a selected frequency can be increased or
decreased, whilst (unlike bandpass and bandreject filters) that at all
other frequencies is unchanged.
In order to produce complex equalisation curves, this filter can be
given several times, each with a different central frequency.
The filter accepts the following options:
frequency, f
Set the filter's central frequency in Hz.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Specify the band-width of a filter in width_type units.
gain, g
Set the required gain or attenuation in dB. Beware of clipping
when using a positive gain.
Examples
· Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
equalizer=f=1000:width_type=h:width=200:g=-10
· Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz
with Q 2:
equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5
highpass
Apply a high-pass filter with 3dB point frequency. The filter can be
either single-pole, or double-pole (the default). The filter roll off
at 6dB per pole per octave (20dB per pole per decade).
The filter accepts the following options:
frequency, f
Set frequency in Hz. Default is 3000.
poles, p
Set number of poles. Default is 2.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Specify the band-width of a filter in width_type units. Applies
only to double-pole filter. The default is 0.707q and gives a
Butterworth response.
join
Join multiple input streams into one multi-channel stream.
The filter accepts the following named parameters:
inputs
Number of input streams. Defaults to 2.
channel_layout
Desired output channel layout. Defaults to stereo.
map Map channels from inputs to output. The argument is a '|'-separated
list of mappings, each in the "input_idx.in_channel-out_channel"
form. input_idx is the 0-based index of the input stream.
in_channel can be either the name of the input channel (e.g. FL for
front left) or its index in the specified input stream. out_channel
is the name of the output channel.
The filter will attempt to guess the mappings when those are not
specified explicitly. It does so by first trying to find an unused
matching input channel and if that fails it picks the first unused
input channel.
E.g. to join 3 inputs (with properly set channel layouts)
ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
To build a 5.1 output from 6 single-channel streams:
ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
out
ladspa
Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-ladspa".
file, f
Specifies the name of LADSPA plugin library to load. If the
environment variable LADSPA_PATH is defined, the LADSPA plugin is
searched in each one of the directories specified by the colon
separated list in LADSPA_PATH, otherwise in the standard LADSPA
paths, which are in this order: HOME/.ladspa/lib/,
/usr/local/lib/ladspa/, /usr/lib/ladspa/.
plugin, p
Specifies the plugin within the library. Some libraries contain
only one plugin, but others contain many of them. If this is not
set filter will list all available plugins within the specified
library.
controls, c
Set the '|' separated list of controls which are zero or more
floating point values that determine the behavior of the loaded
plugin (for example delay, threshold or gain). Controls need to be
defined using the following syntax:
c0=value0|c1=value1|c2=value2|..., where valuei is the value set on
the i-th control. If controls is set to "help", all available
controls and their valid ranges are printed.
sample_rate, s
Specify the sample rate, default to 44100. Only used if plugin have
zero inputs.
nb_samples, n
Set the number of samples per channel per each output frame,
default is 1024. Only used if plugin have zero inputs.
duration, d
Set the minimum duration of the sourced audio. See the function
"av_parse_time()" for the accepted format, also check the "Time
duration" section in the ffmpeg-utils manual. Note that the
resulting duration may be greater than the specified duration, as
the generated audio is always cut at the end of a complete frame.
If not specified, or the expressed duration is negative, the audio
is supposed to be generated forever. Only used if plugin have zero
inputs.
Examples
· List all available plugins within amp (LADSPA example plugin)
library:
ladspa=file=amp
· List all available controls and their valid ranges for "vcf_notch"
plugin from "VCF" library:
ladspa=f=vcf:p=vcf_notch:c=help
· Simulate low quality audio equipment using "Computer Music Toolkit"
(CMT) plugin library:
ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
· Add reverberation to the audio using TAP-plugins (Tom's Audio
Processing plugins):
ladspa=file=tap_reverb:tap_reverb
· Generate white noise, with 0.2 amplitude:
ladspa=file=cmt:noise_source_white:c=c0=.2
· Generate 20 bpm clicks using plugin "C* Click - Metronome" from the
"C* Audio Plugin Suite" (CAPS) library:
ladspa=file=caps:Click:c=c1=20'
· Apply "C* Eq10X2 - Stereo 10-band equaliser" effect:
ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
Commands
This filter supports the following commands:
cN Modify the N-th control value.
If the specified value is not valid, it is ignored and prior one is
kept.
lowpass
Apply a low-pass filter with 3dB point frequency. The filter can be
either single-pole or double-pole (the default). The filter roll off
at 6dB per pole per octave (20dB per pole per decade).
The filter accepts the following options:
frequency, f
Set frequency in Hz. Default is 500.
poles, p
Set number of poles. Default is 2.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Specify the band-width of a filter in width_type units. Applies
only to double-pole filter. The default is 0.707q and gives a
Butterworth response.
pan
Mix channels with specific gain levels. The filter accepts the output
channel layout followed by a set of channels definitions.
This filter is also designed to remap efficiently the channels of an
audio stream.
The filter accepts parameters of the form: "l:outdef:outdef:..."
l output channel layout or number of channels
outdef
output channel specification, of the form:
"out_name=[gain*]in_name[+[gain*]in_name...]"
out_name
output channel to define, either a channel name (FL, FR, etc.) or a
channel number (c0, c1, etc.)
gain
multiplicative coefficient for the channel, 1 leaving the volume
unchanged
in_name
input channel to use, see out_name for details; it is not possible
to mix named and numbered input channels
If the `=' in a channel specification is replaced by `<', then the
gains for that specification will be renormalized so that the total is
1, thus avoiding clipping noise.
Mixing examples
For example, if you want to down-mix from stereo to mono, but with a
bigger factor for the left channel:
pan=1:c0=0.9*c0+0.1*c1
A customized down-mix to stereo that works automatically for 3-, 4-, 5-
and 7-channels surround:
pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
Note that ffmpeg integrates a default down-mix (and up-mix) system that
should be preferred (see "-ac" option) unless you have very specific
needs.
Remapping examples
The channel remapping will be effective if, and only if:
*<gain coefficients are zeroes or ones,>
*<only one input per channel output,>
If all these conditions are satisfied, the filter will notify the user
("Pure channel mapping detected"), and use an optimized and lossless
method to do the remapping.
For example, if you have a 5.1 source and want a stereo audio stream by
dropping the extra channels:
pan="stereo: c0=FL : c1=FR"
Given the same source, you can also switch front left and front right
channels and keep the input channel layout:
pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
If the input is a stereo audio stream, you can mute the front left
channel (and still keep the stereo channel layout) with:
pan="stereo:c1=c1"
Still with a stereo audio stream input, you can copy the right channel
in both front left and right:
pan="stereo: c0=FR : c1=FR"
replaygain
ReplayGain scanner filter. This filter takes an audio stream as an
input and outputs it unchanged. At end of filtering it displays
"track_gain" and "track_peak".
resample
Convert the audio sample format, sample rate and channel layout. This
filter is not meant to be used directly.
silencedetect
Detect silence in an audio stream.
This filter logs a message when it detects that the input audio volume
is less or equal to a noise tolerance value for a duration greater or
equal to the minimum detected noise duration.
The printed times and duration are expressed in seconds.
The filter accepts the following options:
duration, d
Set silence duration until notification (default is 2 seconds).
noise, n
Set noise tolerance. Can be specified in dB (in case "dB" is
appended to the specified value) or amplitude ratio. Default is
-60dB, or 0.001.
Examples
· Detect 5 seconds of silence with -50dB noise tolerance:
silencedetect=n=-50dB:d=5
· Complete example with ffmpeg to detect silence with 0.0001 noise
tolerance in silence.mp3:
ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
treble
Boost or cut treble (upper) frequencies of the audio using a two-pole
shelving filter with a response similar to that of a standard hi-fi's
tone-controls. This is also known as shelving equalisation (EQ).
The filter accepts the following options:
gain, g
Give the gain at whichever is the lower of ~22 kHz and the Nyquist
frequency. Its useful range is about -20 (for a large cut) to +20
(for a large boost). Beware of clipping when using a positive gain.
frequency, f
Set the filter's central frequency and so can be used to extend or
reduce the frequency range to be boosted or cut. The default value
is 3000 Hz.
width_type
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
width, w
Determine how steep is the filter's shelf transition.
volume
Adjust the input audio volume.
The filter accepts the following options:
volume
Set audio volume expression.
Output values are clipped to the maximum value.
The output audio volume is given by the relation:
<output_volume> = <volume> * <input_volume>
Default value for volume is "1.0".
precision
Set the mathematical precision.
This determines which input sample formats will be allowed, which
affects the precision of the volume scaling.
fixed
8-bit fixed-point; limits input sample format to U8, S16, and
S32.
float
32-bit floating-point; limits input sample format to FLT.
(default)
double
64-bit floating-point; limits input sample format to DBL.
eval
Set when the volume expression is evaluated.
It accepts the following values:
once
only evaluate expression once during the filter initialization,
or when the volume command is sent
frame
evaluate expression for each incoming frame
Default value is once.
The volume expression can contain the following parameters.
n frame number (starting at zero)
nb_channels
number of channels
nb_consumed_samples
number of samples consumed by the filter
nb_samples
number of samples in the current frame
pos original frame position in the file
pts frame PTS
sample_rate
sample rate
startpts
PTS at start of stream
startt
time at start of stream
t frame time
tb timestamp timebase
volume
last set volume value
Note that when eval is set to once only the sample_rate and tb
variables are available, all other variables will evaluate to NAN.
Commands
This filter supports the following commands:
volume
Modify the volume expression. The command accepts the same syntax
of the corresponding option.
If the specified expression is not valid, it is kept at its current
value.
Examples
· Halve the input audio volume:
volume=volume=0.5
volume=volume=1/2
volume=volume=-6.0206dB
In all the above example the named key for volume can be omitted,
for example like in:
volume=0.5
· Increase input audio power by 6 decibels using fixed-point
precision:
volume=volume=6dB:precision=fixed
· Fade volume after time 10 with an annihilation period of 5 seconds:
volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
volumedetect
Detect the volume of the input video.
The filter has no parameters. The input is not modified. Statistics
about the volume will be printed in the log when the input stream end
is reached.
In particular it will show the mean volume (root mean square), maximum
volume (on a per-sample basis), and the beginning of a histogram of the
registered volume values (from the maximum value to a cumulated 1/1000
of the samples).
All volumes are in decibels relative to the maximum PCM value.
Examples
Here is an excerpt of the output:
[Parsed_volumedetect_0 0xa23120] mean_volume: -27 dB
[Parsed_volumedetect_0 0xa23120] max_volume: -4 dB
[Parsed_volumedetect_0 0xa23120] histogram_4db: 6
[Parsed_volumedetect_0 0xa23120] histogram_5db: 62
[Parsed_volumedetect_0 0xa23120] histogram_6db: 286
[Parsed_volumedetect_0 0xa23120] histogram_7db: 1042
[Parsed_volumedetect_0 0xa23120] histogram_8db: 2551
[Parsed_volumedetect_0 0xa23120] histogram_9db: 4609
[Parsed_volumedetect_0 0xa23120] histogram_10db: 8409
It means that:
· The mean square energy is approximately -27 dB, or 10^-2.7.
· The largest sample is at -4 dB, or more precisely between -4 dB and
-5 dB.
· There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
In other words, raising the volume by +4 dB does not cause any
clipping, raising it by +5 dB causes clipping for 6 samples, etc.
AUDIO SOURCES
Below is a description of the currently available audio sources.
abuffer
Buffer audio frames, and make them available to the filter chain.
This source is mainly intended for a programmatic use, in particular
through the interface defined in libavfilter/asrc_abuffer.h.
It accepts the following named parameters:
time_base
Timebase which will be used for timestamps of submitted frames. It
must be either a floating-point number or in numerator/denominator
form.
sample_rate
The sample rate of the incoming audio buffers.
sample_fmt
The sample format of the incoming audio buffers. Either a sample
format name or its corresponging integer representation from the
enum AVSampleFormat in libavutil/samplefmt.h
channel_layout
The channel layout of the incoming audio buffers. Either a channel
layout name from channel_layout_map in libavutil/channel_layout.c
or its corresponding integer representation from the AV_CH_LAYOUT_*
macros in libavutil/channel_layout.h
channels
The number of channels of the incoming audio buffers. If both
channels and channel_layout are specified, then they must be
consistent.
Examples
abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
will instruct the source to accept planar 16bit signed stereo at
44100Hz. Since the sample format with name "s16p" corresponds to the
number 6 and the "stereo" channel layout corresponds to the value 0x3,
this is equivalent to:
abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
aevalsrc
Generate an audio signal specified by an expression.
This source accepts in input one or more expressions (one for each
channel), which are evaluated and used to generate a corresponding
audio signal.
This source accepts the following options:
exprs
Set the '|'-separated expressions list for each separate channel.
In case the channel_layout option is not specified, the selected
channel layout depends on the number of provided expressions.
Otherwise the last specified expression is applied to the remaining
output channels.
channel_layout, c
Set the channel layout. The number of channels in the specified
layout must be equal to the number of specified expressions.
duration, d
Set the minimum duration of the sourced audio. See the function
"av_parse_time()" for the accepted format. Note that the resulting
duration may be greater than the specified duration, as the
generated audio is always cut at the end of a complete frame.
If not specified, or the expressed duration is negative, the audio
is supposed to be generated forever.
nb_samples, n
Set the number of samples per channel per each output frame,
default to 1024.
sample_rate, s
Specify the sample rate, default to 44100.
Each expression in exprs can contain the following constants:
n number of the evaluated sample, starting from 0
t time of the evaluated sample expressed in seconds, starting from 0
s sample rate
Examples
· Generate silence:
aevalsrc=0
· Generate a sin signal with frequency of 440 Hz, set sample rate to
8000 Hz:
aevalsrc="sin(440*2*PI*t):s=8000"
· Generate a two channels signal, specify the channel layout (Front
Center + Back Center) explicitly:
aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
· Generate white noise:
aevalsrc="-2+random(0)"
· Generate an amplitude modulated signal:
aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
· Generate 2.5 Hz binaural beats on a 360 Hz carrier:
aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
anullsrc
Null audio source, return unprocessed audio frames. It is mainly useful
as a template and to be employed in analysis / debugging tools, or as
the source for filters which ignore the input data (for example the sox
synth filter).
This source accepts the following options:
channel_layout, cl
Specify the channel layout, and can be either an integer or a
string representing a channel layout. The default value of
channel_layout is "stereo".
Check the channel_layout_map definition in
libavutil/channel_layout.c for the mapping between strings and
channel layout values.
sample_rate, r
Specify the sample rate, and defaults to 44100.
nb_samples, n
Set the number of samples per requested frames.
Examples
· Set the sample rate to 48000 Hz and the channel layout to
AV_CH_LAYOUT_MONO.
anullsrc=r=48000:cl=4
· Do the same operation with a more obvious syntax:
anullsrc=r=48000:cl=mono
All the parameters need to be explicitly defined.
flite
Synthesize a voice utterance using the libflite library.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libflite".
Note that the flite library is not thread-safe.
The filter accepts the following options:
list_voices
If set to 1, list the names of the available voices and exit
immediately. Default value is 0.
nb_samples, n
Set the maximum number of samples per frame. Default value is 512.
textfile
Set the filename containing the text to speak.
text
Set the text to speak.
voice, v
Set the voice to use for the speech synthesis. Default value is
"kal". See also the list_voices option.
Examples
· Read from file speech.txt, and synthetize the text using the
standard flite voice:
flite=textfile=speech.txt
· Read the specified text selecting the "slt" voice:
flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
· Input text to ffmpeg:
ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
· Make ffplay speak the specified text, using "flite" and the "lavfi"
device:
ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
For more information about libflite, check:
<http://www.speech.cs.cmu.edu/flite/>
sine
Generate an audio signal made of a sine wave with amplitude 1/8.
The audio signal is bit-exact.
The filter accepts the following options:
frequency, f
Set the carrier frequency. Default is 440 Hz.
beep_factor, b
Enable a periodic beep every second with frequency beep_factor
times the carrier frequency. Default is 0, meaning the beep is
disabled.
sample_rate, r
Specify the sample rate, default is 44100.
duration, d
Specify the duration of the generated audio stream.
samples_per_frame
Set the number of samples per output frame, default is 1024.
Examples
· Generate a simple 440 Hz sine wave:
sine
· Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5
seconds:
sine=220:4:d=5
sine=f=220:b=4:d=5
sine=frequency=220:beep_factor=4:duration=5
AUDIO SINKS
Below is a description of the currently available audio sinks.
abuffersink
Buffer audio frames, and make them available to the end of filter
chain.
This sink is mainly intended for programmatic use, in particular
through the interface defined in libavfilter/buffersink.h or the
options system.
It accepts a pointer to an AVABufferSinkContext structure, which
defines the incoming buffers' formats, to be passed as the opaque
parameter to "avfilter_init_filter" for initialization.
anullsink
Null audio sink, do absolutely nothing with the input audio. It is
mainly useful as a template and to be employed in analysis / debugging
tools.
VIDEO FILTERS
When you configure your FFmpeg build, you can disable any of the
existing filters using "--disable-filters". The configure output will
show the video filters included in your build.
Below is a description of the currently available video filters.
alphaextract
Extract the alpha component from the input as a grayscale video. This
is especially useful with the alphamerge filter.
alphamerge
Add or replace the alpha component of the primary input with the
grayscale value of a second input. This is intended for use with
alphaextract to allow the transmission or storage of frame sequences
that have alpha in a format that doesn't support an alpha channel.
For example, to reconstruct full frames from a normal YUV-encoded video
and a separate video created with alphaextract, you might use:
movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
Since this filter is designed for reconstruction, it operates on frame
sequences without considering timestamps, and terminates when either
input reaches end of stream. This will cause problems if your encoding
pipeline drops frames. If you're trying to apply an image as an overlay
to a video stream, consider the overlay filter instead.
ass
Same as the subtitles filter, except that it doesn't require libavcodec
and libavformat to work. On the other hand, it is limited to ASS
(Advanced Substation Alpha) subtitles files.
bbox
Compute the bounding box for the non-black pixels in the input frame
luminance plane.
This filter computes the bounding box containing all the pixels with a
luminance value greater than the minimum allowed value. The parameters
describing the bounding box are printed on the filter log.
The filter accepts the following option:
min_val
Set the minimal luminance value. Default is 16.
blackdetect
Detect video intervals that are (almost) completely black. Can be
useful to detect chapter transitions, commercials, or invalid
recordings. Output lines contains the time for the start, end and
duration of the detected black interval expressed in seconds.
In order to display the output lines, you need to set the loglevel at
least to the AV_LOG_INFO value.
The filter accepts the following options:
black_min_duration, d
Set the minimum detected black duration expressed in seconds. It
must be a non-negative floating point number.
Default value is 2.0.
picture_black_ratio_th, pic_th
Set the threshold for considering a picture "black". Express the
minimum value for the ratio:
<nb_black_pixels> / <nb_pixels>
for which a picture is considered black. Default value is 0.98.
pixel_black_th, pix_th
Set the threshold for considering a pixel "black".
The threshold expresses the maximum pixel luminance value for which
a pixel is considered "black". The provided value is scaled
according to the following equation:
<absolute_threshold> = <luminance_minimum_value> + <pixel_black_th> * <luminance_range_size>
luminance_range_size and luminance_minimum_value depend on the
input video format, the range is [0-255] for YUV full-range formats
and [16-235] for YUV non full-range formats.
Default value is 0.10.
The following example sets the maximum pixel threshold to the minimum
value, and detects only black intervals of 2 or more seconds:
blackdetect=d=2:pix_th=0.00
blackframe
Detect frames that are (almost) completely black. Can be useful to
detect chapter transitions or commercials. Output lines consist of the
frame number of the detected frame, the percentage of blackness, the
position in the file if known or -1 and the timestamp in seconds.
In order to display the output lines, you need to set the loglevel at
least to the AV_LOG_INFO value.
The filter accepts the following options:
amount
Set the percentage of the pixels that have to be below the
threshold, defaults to 98.
threshold, thresh
Set the threshold below which a pixel value is considered black,
defaults to 32.
blend
Blend two video frames into each other.
It takes two input streams and outputs one stream, the first input is
the "top" layer and second input is "bottom" layer. Output terminates
when shortest input terminates.
A description of the accepted options follows.
c0_mode
c1_mode
c2_mode
c3_mode
all_mode
Set blend mode for specific pixel component or all pixel components
in case of all_mode. Default value is "normal".
Available values for component modes are:
addition
and
average
burn
darken
difference
divide
dodge
exclusion
hardlight
lighten
multiply
negation
normal
or
overlay
phoenix
pinlight
reflect
screen
softlight
subtract
vividlight
xor
c0_opacity
c1_opacity
c2_opacity
c3_opacity
all_opacity
Set blend opacity for specific pixel component or all pixel
components in case of all_opacity. Only used in combination with
pixel component blend modes.
c0_expr
c1_expr
c2_expr
c3_expr
all_expr
Set blend expression for specific pixel component or all pixel
components in case of all_expr. Note that related mode options will
be ignored if those are set.
The expressions can use the following variables:
N The sequential number of the filtered frame, starting from 0.
X
Y the coordinates of the current sample
W
H the width and height of currently filtered plane
SW
SH Width and height scale depending on the currently filtered
plane. It is the ratio between the corresponding luma plane
number of pixels and the current plane ones. E.g. for YUV4:2:0
the values are "1,1" for the luma plane, and "0.5,0.5" for
chroma planes.
T Time of the current frame, expressed in seconds.
TOP, A
Value of pixel component at current location for first video
frame (top layer).
BOTTOM, B
Value of pixel component at current location for second video
frame (bottom layer).
shortest
Force termination when the shortest input terminates. Default is 0.
repeatlast
Continue applying the last bottom frame after the end of the
stream. A value of 0 disable the filter after the last frame of the
bottom layer is reached. Default is 1.
Examples
· Apply transition from bottom layer to top layer in first 10
seconds:
blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
· Apply 1x1 checkerboard effect:
blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
· Apply uncover left effect:
blend=all_expr='if(gte(N*SW+X,W),A,B)'
· Apply uncover down effect:
blend=all_expr='if(gte(Y-N*SH,0),A,B)'
· Apply uncover up-left effect:
blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
boxblur
Apply boxblur algorithm to the input video.
The filter accepts the following options:
luma_radius, lr
luma_power, lp
chroma_radius, cr
chroma_power, cp
alpha_radius, ar
alpha_power, ap
A description of the accepted options follows.
luma_radius, lr
chroma_radius, cr
alpha_radius, ar
Set an expression for the box radius in pixels used for blurring
the corresponding input plane.
The radius value must be a non-negative number, and must not be
greater than the value of the expression "min(w,h)/2" for the luma
and alpha planes, and of "min(cw,ch)/2" for the chroma planes.
Default value for luma_radius is "2". If not specified,
chroma_radius and alpha_radius default to the corresponding value
set for luma_radius.
The expressions can contain the following constants:
w
h the input width and height in pixels
cw
ch the input chroma image width and height in pixels
hsub
vsub
horizontal and vertical chroma subsample values. For example
for the pixel format "yuv422p" hsub is 2 and vsub is 1.
luma_power, lp
chroma_power, cp
alpha_power, ap
Specify how many times the boxblur filter is applied to the
corresponding plane.
Default value for luma_power is 2. If not specified, chroma_power
and alpha_power default to the corresponding value set for
luma_power.
A value of 0 will disable the effect.
Examples
· Apply a boxblur filter with luma, chroma, and alpha radius set to
2:
boxblur=luma_radius=2:luma_power=1
boxblur=2:1
· Set luma radius to 2, alpha and chroma radius to 0:
boxblur=2:1:cr=0:ar=0
· Set luma and chroma radius to a fraction of the video dimension:
boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
colorbalance
Modify intensity of primary colors (red, green and blue) of input
frames.
The filter allows an input frame to be adjusted in the shadows,
midtones or highlights regions for the red-cyan, green-magenta or blue-
yellow balance.
A positive adjustment value shifts the balance towards the primary
color, a negative value towards the complementary color.
The filter accepts the following options:
rs
gs
bs Adjust red, green and blue shadows (darkest pixels).
rm
gm
bm Adjust red, green and blue midtones (medium pixels).
rh
gh
bh Adjust red, green and blue highlights (brightest pixels).
Allowed ranges for options are "[-1.0, 1.0]". Defaults are 0.
Examples
· Add red color cast to shadows:
colorbalance=rs=.3
colorchannelmixer
Adjust video input frames by re-mixing color channels.
This filter modifies a color channel by adding the values associated to
the other channels of the same pixels. For example if the value to
modify is red, the output value will be:
<red>=<red>*<rr> + <blue>*<rb> + <green>*<rg> + <alpha>*<ra>
The filter accepts the following options:
rr
rg
rb
ra Adjust contribution of input red, green, blue and alpha channels
for output red channel. Default is 1 for rr, and 0 for rg, rb and
ra.
gr
gg
gb
ga Adjust contribution of input red, green, blue and alpha channels
for output green channel. Default is 1 for gg, and 0 for gr, gb
and ga.
br
bg
bb
ba Adjust contribution of input red, green, blue and alpha channels
for output blue channel. Default is 1 for bb, and 0 for br, bg and
ba.
ar
ag
ab
aa Adjust contribution of input red, green, blue and alpha channels
for output alpha channel. Default is 1 for aa, and 0 for ar, ag
and ab.
Allowed ranges for options are "[-2.0, 2.0]".
Examples
· Convert source to grayscale:
colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
· Simulate sepia tones:
colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
colormatrix
Convert color matrix.
The filter accepts the following options:
src
dst Specify the source and destination color matrix. Both values must
be specified.
The accepted values are:
bt709
BT.709
bt601
BT.601
smpte240m
SMPTE-240M
fcc FCC
For example to convert from BT.601 to SMPTE-240M, use the command:
colormatrix=bt601:smpte240m
copy
Copy the input source unchanged to the output. Mainly useful for
testing purposes.
crop
Crop the input video to given dimensions.
The filter accepts the following options:
w, out_w
Width of the output video. It defaults to "iw". This expression is
evaluated only once during the filter configuration.
h, out_h
Height of the output video. It defaults to "ih". This expression
is evaluated only once during the filter configuration.
x Horizontal position, in the input video, of the left edge of the
output video. It defaults to "(in_w-out_w)/2". This expression is
evaluated per-frame.
y Vertical position, in the input video, of the top edge of the
output video. It defaults to "(in_h-out_h)/2". This expression is
evaluated per-frame.
keep_aspect
If set to 1 will force the output display aspect ratio to be the
same of the input, by changing the output sample aspect ratio. It
defaults to 0.
The out_w, out_h, x, y parameters are expressions containing the
following constants:
x
y the computed values for x and y. They are evaluated for each new
frame.
in_w
in_h
the input width and height
iw
ih same as in_w and in_h
out_w
out_h
the output (cropped) width and height
ow
oh same as out_w and out_h
a same as iw / ih
sar input sample aspect ratio
dar input display aspect ratio, it is the same as (iw / ih) * sar
hsub
vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
n the number of input frame, starting from 0
pos the position in the file of the input frame, NAN if unknown
t timestamp expressed in seconds, NAN if the input timestamp is
unknown
The expression for out_w may depend on the value of out_h, and the
expression for out_h may depend on out_w, but they cannot depend on x
and y, as x and y are evaluated after out_w and out_h.
The x and y parameters specify the expressions for the position of the
top-left corner of the output (non-cropped) area. They are evaluated
for each frame. If the evaluated value is not valid, it is approximated
to the nearest valid value.
The expression for x may depend on y, and the expression for y may
depend on x.
Examples
· Crop area with size 100x100 at position (12,34).
crop=100:100:12:34
Using named options, the example above becomes:
crop=w=100:h=100:x=12:y=34
· Crop the central input area with size 100x100:
crop=100:100
· Crop the central input area with size 2/3 of the input video:
crop=2/3*in_w:2/3*in_h
· Crop the input video central square:
crop=out_w=in_h
crop=in_h
· Delimit the rectangle with the top-left corner placed at position
100:100 and the right-bottom corner corresponding to the right-
bottom corner of the input image:
crop=in_w-100:in_h-100:100:100
· Crop 10 pixels from the left and right borders, and 20 pixels from
the top and bottom borders
crop=in_w-2*10:in_h-2*20
· Keep only the bottom right quarter of the input image:
crop=in_w/2:in_h/2:in_w/2:in_h/2
· Crop height for getting Greek harmony:
crop=in_w:1/PHI*in_w
· Appply trembling effect:
crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)
· Apply erratic camera effect depending on timestamp:
crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
· Set x depending on the value of y:
crop=in_w/2:in_h/2:y:10+10*sin(n/10)
cropdetect
Auto-detect crop size.
Calculate necessary cropping parameters and prints the recommended
parameters through the logging system. The detected dimensions
correspond to the non-black area of the input video.
The filter accepts the following options:
limit
Set higher black value threshold, which can be optionally specified
from nothing (0) to everything (255). An intensity value greater to
the set value is considered non-black. Default value is 24.
round
Set the value for which the width/height should be divisible by.
The offset is automatically adjusted to center the video. Use 2 to
get only even dimensions (needed for 4:2:2 video). 16 is best when
encoding to most video codecs. Default value is 16.
reset_count, reset
Set the counter that determines after how many frames cropdetect
will reset the previously detected largest video area and start
over to detect the current optimal crop area. Default value is 0.
This can be useful when channel logos distort the video area. 0
indicates never reset and return the largest area encountered
during playback.
curves
Apply color adjustments using curves.
This filter is similar to the Adobe Photoshop and GIMP curves tools.
Each component (red, green and blue) has its values defined by N key
points tied from each other using a smooth curve. The x-axis represents
the pixel values from the input frame, and the y-axis the new pixel
values to be set for the output frame.
By default, a component curve is defined by the two points (0;0) and
(1;1). This creates a straight line where each original pixel value is
"adjusted" to its own value, which means no change to the image.
The filter allows you to redefine these two points and add some more. A
new curve (using a natural cubic spline interpolation) will be define
to pass smoothly through all these new coordinates. The new defined
points needs to be strictly increasing over the x-axis, and their x and
y values must be in the [0;1] interval. If the computed curves
happened to go outside the vector spaces, the values will be clipped
accordingly.
If there is no key point defined in "x=0", the filter will
automatically insert a (0;0) point. In the same way, if there is no key
point defined in "x=1", the filter will automatically insert a (1;1)
point.
The filter accepts the following options:
preset
Select one of the available color presets. This option can be used
in addition to the r, g, b parameters; in this case, the later
options takes priority on the preset values. Available presets
are:
none
color_negative
cross_process
darker
increase_contrast
lighter
linear_contrast
medium_contrast
negative
strong_contrast
vintage
Default is "none".
master, m
Set the master key points. These points will define a second pass
mapping. It is sometimes called a "luminance" or "value" mapping.
It can be used with r, g, b or all since it acts like a post-
processing LUT.
red, r
Set the key points for the red component.
green, g
Set the key points for the green component.
blue, b
Set the key points for the blue component.
all Set the key points for all components (not including master). Can
be used in addition to the other key points component options. In
this case, the unset component(s) will fallback on this all
setting.
psfile
Specify a Photoshop curves file (".asv") to import the settings
from.
To avoid some filtergraph syntax conflicts, each key points list need
to be defined using the following syntax: "x0/y0 x1/y1 x2/y2 ...".
Examples
· Increase slightly the middle level of blue:
curves=blue='0.5/0.58'
· Vintage effect:
curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
Here we obtain the following coordinates for each components:
red "(0;0.11) (0.42;0.51) (1;0.95)"
green
"(0;0) (0.50;0.48) (1;1)"
blue
"(0;0.22) (0.49;0.44) (1;0.80)"
· The previous example can also be achieved with the associated
built-in preset:
curves=preset=vintage
· Or simply:
curves=vintage
· Use a Photoshop preset and redefine the points of the green
component:
curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53'
dctdnoiz
Denoise frames using 2D DCT (frequency domain filtering).
This filter is not designed for real time and can be extremely slow.
The filter accepts the following options:
sigma, s
Set the noise sigma constant.
This sigma defines a hard threshold of "3 * sigma"; every DCT
coefficient (absolute value) below this threshold with be dropped.
If you need a more advanced filtering, see expr.
Default is 0.
overlap
Set number overlapping pixels for each block. Each block is of size
"16x16". Since the filter can be slow, you may want to reduce this
value, at the cost of a less effective filter and the risk of
various artefacts.
If the overlapping value doesn't allow to process the whole input
width or height, a warning will be displayed and according borders
won't be denoised.
Default value is 15.
expr, e
Set the coefficient factor expression.
For each coefficient of a DCT block, this expression will be
evaluated as a multiplier value for the coefficient.
If this is option is set, the sigma option will be ignored.
The absolute value of the coefficient can be accessed through the c
variable.
Examples
Apply a denoise with a sigma of 4.5:
dctdnoiz=4.5
The same operation can be achieved using the expression system:
dctdnoiz=e='gte(c, 4.5*3)'
decimate
Drop duplicated frames at regular intervals.
The filter accepts the following options:
cycle
Set the number of frames from which one will be dropped. Setting
this to N means one frame in every batch of N frames will be
dropped. Default is 5.
dupthresh
Set the threshold for duplicate detection. If the difference metric
for a frame is less than or equal to this value, then it is
declared as duplicate. Default is 1.1
scthresh
Set scene change threshold. Default is 15.
blockx
blocky
Set the size of the x and y-axis blocks used during metric
calculations. Larger blocks give better noise suppression, but
also give worse detection of small movements. Must be a power of
two. Default is 32.
ppsrc
Mark main input as a pre-processed input and activate clean source
input stream. This allows the input to be pre-processed with
various filters to help the metrics calculation while keeping the
frame selection lossless. When set to 1, the first stream is for
the pre-processed input, and the second stream is the clean source
from where the kept frames are chosen. Default is 0.
chroma
Set whether or not chroma is considered in the metric calculations.
Default is 1.
dejudder
Remove judder produced by partially interlaced telecined content.
Judder can be introduced, for instance, by pullup filter. If the
original source was partially telecined content then the output of
"pullup,dejudder" will have a variable frame rate. May change the
recorded frame rate of the container. Aside from that change, this
filter will not affect constant frame rate video.
The option available in this filter is:
cycle
Specify the length of the window over which the judder repeats.
Accepts any interger greater than 1. Useful values are:
4 If the original was telecined from 24 to 30 fps (Film to NTSC).
5 If the original was telecined from 25 to 30 fps (PAL to NTSC).
20 If a mixture of the two.
The default is 4.
delogo
Suppress a TV station logo by a simple interpolation of the surrounding
pixels. Just set a rectangle covering the logo and watch it disappear
(and sometimes something even uglier appear - your mileage may vary).
This filter accepts the following options:
x
y Specify the top left corner coordinates of the logo. They must be
specified.
w
h Specify the width and height of the logo to clear. They must be
specified.
band, t
Specify the thickness of the fuzzy edge of the rectangle (added to
w and h). The default value is 4.
show
When set to 1, a green rectangle is drawn on the screen to simplify
finding the right x, y, w, and h parameters. The default value is
0.
The rectangle is drawn on the outermost pixels which will be
(partly) replaced with interpolated values. The values of the next
pixels immediately outside this rectangle in each direction will be
used to compute the interpolated pixel values inside the rectangle.
Examples
· Set a rectangle covering the area with top left corner coordinates
0,0 and size 100x77, setting a band of size 10:
delogo=x=0:y=0:w=100:h=77:band=10
deshake
Attempt to fix small changes in horizontal and/or vertical shift. This
filter helps remove camera shake from hand-holding a camera, bumping a
tripod, moving on a vehicle, etc.
The filter accepts the following options:
x
y
w
h Specify a rectangular area where to limit the search for motion
vectors. If desired the search for motion vectors can be limited
to a rectangular area of the frame defined by its top left corner,
width and height. These parameters have the same meaning as the
drawbox filter which can be used to visualise the position of the
bounding box.
This is useful when simultaneous movement of subjects within the
frame might be confused for camera motion by the motion vector
search.
If any or all of x, y, w and h are set to -1 then the full frame is
used. This allows later options to be set without specifying the
bounding box for the motion vector search.
Default - search the whole frame.
rx
ry Specify the maximum extent of movement in x and y directions in the
range 0-64 pixels. Default 16.
edge
Specify how to generate pixels to fill blanks at the edge of the
frame. Available values are:
blank, 0
Fill zeroes at blank locations
original, 1
Original image at blank locations
clamp, 2
Extruded edge value at blank locations
mirror, 3
Mirrored edge at blank locations
Default value is mirror.
blocksize
Specify the blocksize to use for motion search. Range 4-128 pixels,
default 8.
contrast
Specify the contrast threshold for blocks. Only blocks with more
than the specified contrast (difference between darkest and
lightest pixels) will be considered. Range 1-255, default 125.
search
Specify the search strategy. Available values are:
exhaustive, 0
Set exhaustive search
less, 1
Set less exhaustive search.
Default value is exhaustive.
filename
If set then a detailed log of the motion search is written to the
specified file.
opencl
If set to 1, specify using OpenCL capabilities, only available if
FFmpeg was configured with "--enable-opencl". Default value is 0.
drawbox
Draw a colored box on the input image.
This filter accepts the following options:
x
y The expressions which specify the top left corner coordinates of
the box. Default to 0.
width, w
height, h
The expressions which specify the width and height of the box, if 0
they are interpreted as the input width and height. Default to 0.
color, c
Specify the color of the box to write. For the general syntax of
this option, check the "Color" section in the ffmpeg-utils manual.
If the special value "invert" is used, the box edge color is the
same as the video with inverted luma.
thickness, t
The expression which sets the thickness of the box edge. Default
value is 3.
See below for the list of accepted constants.
The parameters for x, y, w and h and t are expressions containing the
following constants:
dar The input display aspect ratio, it is the same as (w / h) * sar.
hsub
vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
in_h, ih
in_w, iw
The input width and height.
sar The input sample aspect ratio.
x
y The x and y offset coordinates where the box is drawn.
w
h The width and height of the drawn box.
t The thickness of the drawn box.
These constants allow the x, y, w, h and t expressions to refer to
each other, so you may for example specify "y=x/dar" or "h=w/dar".
Examples
· Draw a black box around the edge of the input image:
drawbox
· Draw a box with color red and an opacity of 50%:
drawbox=10:20:200:60:red@0.5
The previous example can be specified as:
drawbox=x=10:y=20:w=200:h=60:color=red@0.5
· Fill the box with pink color:
drawbox=x=10:y=10:w=100:h=100:color=pink@0.5:t=max
· Draw a 2-pixel red 2.40:1 mask:
drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red
drawgrid
Draw a grid on the input image.
This filter accepts the following options:
x
y The expressions which specify the coordinates of some point of grid
intersection (meant to configure offset). Both default to 0.
width, w
height, h
The expressions which specify the width and height of the grid
cell, if 0 they are interpreted as the input width and height,
respectively, minus "thickness", so image gets framed. Default to
0.
color, c
Specify the color of the grid. For the general syntax of this
option, check the "Color" section in the ffmpeg-utils manual. If
the special value "invert" is used, the grid color is the same as
the video with inverted luma.
thickness, t
The expression which sets the thickness of the grid line. Default
value is 1.
See below for the list of accepted constants.
The parameters for x, y, w and h and t are expressions containing the
following constants:
dar The input display aspect ratio, it is the same as (w / h) * sar.
hsub
vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
in_h, ih
in_w, iw
The input grid cell width and height.
sar The input sample aspect ratio.
x
y The x and y coordinates of some point of grid intersection (meant
to configure offset).
w
h The width and height of the drawn cell.
t The thickness of the drawn cell.
These constants allow the x, y, w, h and t expressions to refer to
each other, so you may for example specify "y=x/dar" or "h=w/dar".
Examples
· Draw a grid with cell 100x100 pixels, thickness 2 pixels, with
color red and an opacity of 50%:
drawgrid=width=100:height=100:thickness=2:color=red@0.5
· Draw a white 3x3 grid with an opacity of 50%:
drawgrid=w=iw/3:h=ih/3:t=2:c=white@0.5
drawtext
Draw text string or text from specified file on top of video using the
libfreetype library.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libfreetype".
Syntax
The description of the accepted parameters follows.
box Used to draw a box around text using background color. Value
should be either 1 (enable) or 0 (disable). The default value of
box is 0.
boxcolor
The color to be used for drawing box around text. For the syntax of
this option, check the "Color" section in the ffmpeg-utils manual.
The default value of boxcolor is "white".
borderw
Set the width of the border to be drawn around the text using
bordercolor. The default value of borderw is 0.
bordercolor
Set the color to be used for drawing border around text. For the
syntax of this option, check the "Color" section in the ffmpeg-
utils manual.
The default value of bordercolor is "black".
expansion
Select how the text is expanded. Can be either "none", "strftime"
(deprecated) or "normal" (default). See the drawtext_expansion,
Text expansion section below for details.
fix_bounds
If true, check and fix text coords to avoid clipping.
fontcolor
The color to be used for drawing fonts. For the syntax of this
option, check the "Color" section in the ffmpeg-utils manual.
The default value of fontcolor is "black".
fontfile
The font file to be used for drawing text. Path must be included.
This parameter is mandatory.
fontsize
The font size to be used for drawing text. The default value of
fontsize is 16.
ft_load_flags
Flags to be used for loading the fonts.
The flags map the corresponding flags supported by libfreetype, and
are a combination of the following values:
default
no_scale
no_hinting
render
no_bitmap
vertical_layout
force_autohint
crop_bitmap
pedantic
ignore_global_advance_width
no_recurse
ignore_transform
monochrome
linear_design
no_autohint
Default value is "default".
For more information consult the documentation for the FT_LOAD_*
libfreetype flags.
shadowcolor
The color to be used for drawing a shadow behind the drawn text.
For the syntax of this option, check the "Color" section in the
ffmpeg-utils manual.
The default value of shadowcolor is "black".
shadowx
shadowy
The x and y offsets for the text shadow position with respect to
the position of the text. They can be either positive or negative
values. Default value for both is "0".
start_number
The starting frame number for the n/frame_num variable. The default
value is "0".
tabsize
The size in number of spaces to use for rendering the tab. Default
value is 4.
timecode
Set the initial timecode representation in "hh:mm:ss[:;.]ff"
format. It can be used with or without text parameter.
timecode_rate option must be specified.
timecode_rate, rate, r
Set the timecode frame rate (timecode only).
text
The text string to be drawn. The text must be a sequence of UTF-8
encoded characters. This parameter is mandatory if no file is
specified with the parameter textfile.
textfile
A text file containing text to be drawn. The text must be a
sequence of UTF-8 encoded characters.
This parameter is mandatory if no text string is specified with the
parameter text.
If both text and textfile are specified, an error is thrown.
reload
If set to 1, the textfile will be reloaded before each frame. Be
sure to update it atomically, or it may be read partially, or even
fail.
x
y The expressions which specify the offsets where text will be drawn
within the video frame. They are relative to the top/left border of
the output image.
The default value of x and y is "0".
See below for the list of accepted constants and functions.
The parameters for x and y are expressions containing the following
constants and functions:
dar input display aspect ratio, it is the same as (w / h) * sar
hsub
vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
line_h, lh
the height of each text line
main_h, h, H
the input height
main_w, w, W
the input width
max_glyph_a, ascent
the maximum distance from the baseline to the highest/upper grid
coordinate used to place a glyph outline point, for all the
rendered glyphs. It is a positive value, due to the grid's
orientation with the Y axis upwards.
max_glyph_d, descent
the maximum distance from the baseline to the lowest grid
coordinate used to place a glyph outline point, for all the
rendered glyphs. This is a negative value, due to the grid's
orientation, with the Y axis upwards.
max_glyph_h
maximum glyph height, that is the maximum height for all the glyphs
contained in the rendered text, it is equivalent to ascent -
descent.
max_glyph_w
maximum glyph width, that is the maximum width for all the glyphs
contained in the rendered text
n the number of input frame, starting from 0
rand(min, max)
return a random number included between min and max
sar input sample aspect ratio
t timestamp expressed in seconds, NAN if the input timestamp is
unknown
text_h, th
the height of the rendered text
text_w, tw
the width of the rendered text
x
y the x and y offset coordinates where the text is drawn.
These parameters allow the x and y expressions to refer each other,
so you can for example specify "y=x/dar".
If libavfilter was built with "--enable-fontconfig", then fontfile can
be a fontconfig pattern or omitted.
Text expansion
If expansion is set to "strftime", the filter recognizes strftime()
sequences in the provided text and expands them accordingly. Check the
documentation of strftime(). This feature is deprecated.
If expansion is set to "none", the text is printed verbatim.
If expansion is set to "normal" (which is the default), the following
expansion mechanism is used.
The backslash character '\', followed by any character, always expands
to the second character.
Sequence of the form "%{...}" are expanded. The text between the braces
is a function name, possibly followed by arguments separated by ':'.
If the arguments contain special characters or delimiters (':' or '}'),
they should be escaped.
Note that they probably must also be escaped as the value for the text
option in the filter argument string and as the filter argument in the
filtergraph description, and possibly also for the shell, that makes up
to four levels of escaping; using a text file avoids these problems.
The following functions are available:
expr, e
The expression evaluation result.
It must take one argument specifying the expression to be
evaluated, which accepts the same constants and functions as the x
and y values. Note that not all constants should be used, for
example the text size is not known when evaluating the expression,
so the constants text_w and text_h will have an undefined value.
gmtime
The time at which the filter is running, expressed in UTC. It can
accept an argument: a strftime() format string.
localtime
The time at which the filter is running, expressed in the local
time zone. It can accept an argument: a strftime() format string.
metadata
Frame metadata. It must take one argument specifying metadata key.
n, frame_num
The frame number, starting from 0.
pict_type
A 1 character description of the current picture type.
pts The timestamp of the current frame, in seconds, with microsecond
accuracy.
Examples
· Draw "Test Text" with font FreeSerif, using the default values for
the optional parameters.
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
· Draw 'Test Text' with font FreeSerif of size 24 at position x=100
and y=50 (counting from the top-left corner of the screen), text is
yellow with a red box around it. Both the text and the box have an
opacity of 20%.
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"
Note that the double quotes are not necessary if spaces are not
used within the parameter list.
· Show the text at the center of the video frame:
drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
· Show a text line sliding from right to left in the last row of the
video frame. The file LONG_LINE is assumed to contain a single line
with no newlines.
drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
· Show the content of file CREDITS off the bottom of the frame and
scroll up.
drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
· Draw a single green letter "g", at the center of the input video.
The glyph baseline is placed at half screen height.
drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
· Show text for 1 second every 3 seconds:
drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
· Use fontconfig to set the font. Note that the colons need to be
escaped.
drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
· Print the date of a real-time encoding (see strftime(3)):
drawtext='fontfile=FreeSans.ttf:text=%{localtime:%a %b %d %Y}'
For more information about libfreetype, check:
<http://www.freetype.org/>.
For more information about fontconfig, check:
<http://freedesktop.org/software/fontconfig/fontconfig-user.html>.
edgedetect
Detect and draw edges. The filter uses the Canny Edge Detection
algorithm.
The filter accepts the following options:
low
high
Set low and high threshold values used by the Canny thresholding
algorithm.
The high threshold selects the "strong" edge pixels, which are then
connected through 8-connectivity with the "weak" edge pixels
selected by the low threshold.
low and high threshold values must be chosen in the range [0,1],
and low should be lesser or equal to high.
Default value for low is "20/255", and default value for high is
"50/255".
Example:
edgedetect=low=0.1:high=0.4
extractplanes
Extract color channel components from input video stream into separate
grayscale video streams.
The filter accepts the following option:
planes
Set plane(s) to extract.
Available values for planes are:
y
u
v
a
r
g
b
Choosing planes not available in the input will result in an error.
That means you cannot select "r", "g", "b" planes with "y", "u",
"v" planes at same time.
Examples
· Extract luma, u and v color channel component from input video
frame into 3 grayscale outputs:
ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi
elbg
Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
For each input image, the filter will compute the optimal mapping from
the input to the output given the codebook length, that is the number
of distinct output colors.
This filter accepts the following options.
codebook_length, l
Set codebook length. The value must be a positive integer, and
represents the number of distinct output colors. Default value is
256.
nb_steps, n
Set the maximum number of iterations to apply for computing the
optimal mapping. The higher the value the better the result and the
higher the computation time. Default value is 1.
seed, s
Set a random seed, must be an integer included between 0 and
UINT32_MAX. If not specified, or if explicitly set to -1, the
filter will try to use a good random seed on a best effort basis.
fade
Apply fade-in/out effect to input video.
This filter accepts the following options:
type, t
The effect type -- can be either "in" for fade-in, or "out" for a
fade-out effect. Default is "in".
start_frame, s
Specify the number of the start frame for starting to apply the
fade effect. Default is 0.
nb_frames, n
The number of frames for which the fade effect has to last. At the
end of the fade-in effect the output video will have the same
intensity as the input video, at the end of the fade-out transition
the output video will be filled with the selected color. Default
is 25.
alpha
If set to 1, fade only alpha channel, if one exists on the input.
Default value is 0.
start_time, st
Specify the timestamp (in seconds) of the frame to start to apply
the fade effect. If both start_frame and start_time are specified,
the fade will start at whichever comes last. Default is 0.
duration, d
The number of seconds for which the fade effect has to last. At the
end of the fade-in effect the output video will have the same
intensity as the input video, at the end of the fade-out transition
the output video will be filled with the selected color. If both
duration and nb_frames are specified, duration is used. Default is
0.
color, c
Specify the color of the fade. Default is "black".
Examples
· Fade in first 30 frames of video:
fade=in:0:30
The command above is equivalent to:
fade=t=in:s=0:n=30
· Fade out last 45 frames of a 200-frame video:
fade=out:155:45
fade=type=out:start_frame=155:nb_frames=45
· Fade in first 25 frames and fade out last 25 frames of a 1000-frame
video:
fade=in:0:25, fade=out:975:25
· Make first 5 frames yellow, then fade in from frame 5-24:
fade=in:5:20:color=yellow
· Fade in alpha over first 25 frames of video:
fade=in:0:25:alpha=1
· Make first 5.5 seconds black, then fade in for 0.5 seconds:
fade=t=in:st=5.5:d=0.5
field
Extract a single field from an interlaced image using stride arithmetic
to avoid wasting CPU time. The output frames are marked as non-
interlaced.
The filter accepts the following options:
type
Specify whether to extract the top (if the value is 0 or "top") or
the bottom field (if the value is 1 or "bottom").
fieldmatch
Field matching filter for inverse telecine. It is meant to reconstruct
the progressive frames from a telecined stream. The filter does not
drop duplicated frames, so to achieve a complete inverse telecine
"fieldmatch" needs to be followed by a decimation filter such as
decimate in the filtergraph.
The separation of the field matching and the decimation is notably
motivated by the possibility of inserting a de-interlacing filter
fallback between the two. If the source has mixed telecined and real
interlaced content, "fieldmatch" will not be able to match fields for
the interlaced parts. But these remaining combed frames will be marked
as interlaced, and thus can be de-interlaced by a later filter such as
yadif before decimation.
In addition to the various configuration options, "fieldmatch" can take
an optional second stream, activated through the ppsrc option. If
enabled, the frames reconstruction will be based on the fields and
frames from this second stream. This allows the first input to be pre-
processed in order to help the various algorithms of the filter, while
keeping the output lossless (assuming the fields are matched properly).
Typically, a field-aware denoiser, or brightness/contrast adjustments
can help.
Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth
project) and VIVTC/VFM (VapourSynth project). The later is a light
clone of TFM from which "fieldmatch" is based on. While the semantic
and usage are very close, some behaviour and options names can differ.
The filter accepts the following options:
order
Specify the assumed field order of the input stream. Available
values are:
auto
Auto detect parity (use FFmpeg's internal parity value).
bff Assume bottom field first.
tff Assume top field first.
Note that it is sometimes recommended not to trust the parity
announced by the stream.
Default value is auto.
mode
Set the matching mode or strategy to use. pc mode is the safest in
the sense that it won't risk creating jerkiness due to duplicate
frames when possible, but if there are bad edits or blended fields
it will end up outputting combed frames when a good match might
actually exist. On the other hand, pcn_ub mode is the most risky in
terms of creating jerkiness, but will almost always find a good
frame if there is one. The other values are all somewhere in
between pc and pcn_ub in terms of risking jerkiness and creating
duplicate frames versus finding good matches in sections with bad
edits, orphaned fields, blended fields, etc.
More details about p/c/n/u/b are available in p/c/n/u/b meaning
section.
Available values are:
pc 2-way matching (p/c)
pc_n
2-way matching, and trying 3rd match if still combed (p/c + n)
pc_u
2-way matching, and trying 3rd match (same order) if still
combed (p/c + u)
pc_n_ub
2-way matching, trying 3rd match if still combed, and trying
4th/5th matches if still combed (p/c + n + u/b)
pcn 3-way matching (p/c/n)
pcn_ub
3-way matching, and trying 4th/5th matches if all 3 of the
original matches are detected as combed (p/c/n + u/b)
The parenthesis at the end indicate the matches that would be used
for that mode assuming order=tff (and field on auto or top).
In terms of speed pc mode is by far the fastest and pcn_ub is the
slowest.
Default value is pc_n.
ppsrc
Mark the main input stream as a pre-processed input, and enable the
secondary input stream as the clean source to pick the fields from.
See the filter introduction for more details. It is similar to the
clip2 feature from VFM/TFM.
Default value is 0 (disabled).
field
Set the field to match from. It is recommended to set this to the
same value as order unless you experience matching failures with
that setting. In certain circumstances changing the field that is
used to match from can have a large impact on matching performance.
Available values are:
auto
Automatic (same value as order).
bottom
Match from the bottom field.
top Match from the top field.
Default value is auto.
mchroma
Set whether or not chroma is included during the match comparisons.
In most cases it is recommended to leave this enabled. You should
set this to 0 only if your clip has bad chroma problems such as
heavy rainbowing or other artifacts. Setting this to 0 could also
be used to speed things up at the cost of some accuracy.
Default value is 1.
y0
y1 These define an exclusion band which excludes the lines between y0
and y1 from being included in the field matching decision. An
exclusion band can be used to ignore subtitles, a logo, or other
things that may interfere with the matching. y0 sets the starting
scan line and y1 sets the ending line; all lines in between y0 and
y1 (including y0 and y1) will be ignored. Setting y0 and y1 to the
same value will disable the feature. y0 and y1 defaults to 0.
scthresh
Set the scene change detection threshold as a percentage of maximum
change on the luma plane. Good values are in the "[8.0, 14.0]"
range. Scene change detection is only relevant in case
combmatch=sc. The range for scthresh is "[0.0, 100.0]".
Default value is 12.0.
combmatch
When combatch is not none, "fieldmatch" will take into account the
combed scores of matches when deciding what match to use as the
final match. Available values are:
none
No final matching based on combed scores.
sc Combed scores are only used when a scene change is detected.
full
Use combed scores all the time.
Default is sc.
combdbg
Force "fieldmatch" to calculate the combed metrics for certain
matches and print them. This setting is known as micout in TFM/VFM
vocabulary. Available values are:
none
No forced calculation.
pcn Force p/c/n calculations.
pcnub
Force p/c/n/u/b calculations.
Default value is none.
cthresh
This is the area combing threshold used for combed frame detection.
This essentially controls how "strong" or "visible" combing must be
to be detected. Larger values mean combing must be more visible
and smaller values mean combing can be less visible or strong and
still be detected. Valid settings are from "-1" (every pixel will
be detected as combed) to 255 (no pixel will be detected as
combed). This is basically a pixel difference value. A good range
is "[8, 12]".
Default value is 9.
chroma
Sets whether or not chroma is considered in the combed frame
decision. Only disable this if your source has chroma problems
(rainbowing, etc.) that are causing problems for the combed frame
detection with chroma enabled. Actually, using chroma=0 is usually
more reliable, except for the case where there is chroma only
combing in the source.
Default value is 0.
blockx
blocky
Respectively set the x-axis and y-axis size of the window used
during combed frame detection. This has to do with the size of the
area in which combpel pixels are required to be detected as combed
for a frame to be declared combed. See the combpel parameter
description for more info. Possible values are any number that is
a power of 2 starting at 4 and going up to 512.
Default value is 16.
combpel
The number of combed pixels inside any of the blocky by blockx size
blocks on the frame for the frame to be detected as combed. While
cthresh controls how "visible" the combing must be, this setting
controls "how much" combing there must be in any localized area (a
window defined by the blockx and blocky settings) on the frame.
Minimum value is 0 and maximum is "blocky x blockx" (at which point
no frames will ever be detected as combed). This setting is known
as MI in TFM/VFM vocabulary.
Default value is 80.
p/c/n/u/b meaning
p/c/n
We assume the following telecined stream:
Top fields: 1 2 2 3 4
Bottom fields: 1 2 3 4 4
The numbers correspond to the progressive frame the fields relate to.
Here, the first two frames are progressive, the 3rd and 4th are combed,
and so on.
When "fieldmatch" is configured to run a matching from bottom
(field=bottom) this is how this input stream get transformed:
Input stream:
T 1 2 2 3 4
B 1 2 3 4 4 <-- matching reference
Matches: c c n n c
Output stream:
T 1 2 3 4 4
B 1 2 3 4 4
As a result of the field matching, we can see that some frames get
duplicated. To perform a complete inverse telecine, you need to rely
on a decimation filter after this operation. See for instance the
decimate filter.
The same operation now matching from top fields (field=top) looks like
this:
Input stream:
T 1 2 2 3 4 <-- matching reference
B 1 2 3 4 4
Matches: c c p p c
Output stream:
T 1 2 2 3 4
B 1 2 2 3 4
In these examples, we can see what p, c and n mean; basically, they
refer to the frame and field of the opposite parity:
*<p matches the field of the opposite parity in the previous frame>
*<c matches the field of the opposite parity in the current frame>
*<n matches the field of the opposite parity in the next frame>
u/b
The u and b matching are a bit special in the sense that they match
from the opposite parity flag. In the following examples, we assume
that we are currently matching the 2nd frame (Top:2, bottom:2).
According to the match, a 'x' is placed above and below each matched
fields.
With bottom matching (field=bottom):
Match: c p n b u
x x x x x
Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
x x x x x
Output frames:
2 1 2 2 2
2 2 2 1 3
With top matching (field=top):
Match: c p n b u
x x x x x
Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
x x x x x
Output frames:
2 2 2 1 2
2 1 3 2 2
Examples
Simple IVTC of a top field first telecined stream:
fieldmatch=order=tff:combmatch=none, decimate
Advanced IVTC, with fallback on yadif for still combed frames:
fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
fieldorder
Transform the field order of the input video.
This filter accepts the following options:
order
Output field order. Valid values are tff for top field first or bff
for bottom field first.
Default value is tff.
Transformation is achieved by shifting the picture content up or down
by one line, and filling the remaining line with appropriate picture
content. This method is consistent with most broadcast field order
converters.
If the input video is not flagged as being interlaced, or it is already
flagged as being of the required output field order then this filter
does not alter the incoming video.
This filter is very useful when converting to or from PAL DV material,
which is bottom field first.
For example:
ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
fifo
Buffer input images and send them when they are requested.
This filter is mainly useful when auto-inserted by the libavfilter
framework.
The filter does not take parameters.
format
Convert the input video to one of the specified pixel formats.
Libavfilter will try to pick one that is supported for the input to the
next filter.
This filter accepts the following parameters:
pix_fmts
A '|'-separated list of pixel format names, for example
"pix_fmts=yuv420p|monow|rgb24".
Examples
· Convert the input video to the format yuv420p
format=pix_fmts=yuv420p
Convert the input video to any of the formats in the list
format=pix_fmts=yuv420p|yuv444p|yuv410p
fps
Convert the video to specified constant frame rate by duplicating or
dropping frames as necessary.
This filter accepts the following named parameters:
fps Desired output frame rate. The default is 25.
round
Rounding method.
Possible values are:
zero
zero round towards 0
inf round away from 0
down
round towards -infinity
up round towards +infinity
near
round to nearest
The default is "near".
start_time
Assume the first PTS should be the given value, in seconds. This
allows for padding/trimming at the start of stream. By default, no
assumption is made about the first frame's expected PTS, so no
padding or trimming is done. For example, this could be set to 0
to pad the beginning with duplicates of the first frame if a video
stream starts after the audio stream or to trim any frames with a
negative PTS.
Alternatively, the options can be specified as a flat string:
fps[:round].
See also the setpts filter.
Examples
· A typical usage in order to set the fps to 25:
fps=fps=25
· Sets the fps to 24, using abbreviation and rounding method to round
to nearest:
fps=fps=film:round=near
framepack
Pack two different video streams into a stereoscopic video, setting
proper metadata on supported codecs. The two views should have the same
size and framerate and processing will stop when the shorter video
ends. Please note that you may conveniently adjust view properties with
the scale and fps filters.
This filter accepts the following named parameters:
format
Desired packing format. Supported values are:
sbs Views are next to each other (default).
tab Views are on top of each other.
lines
Views are packed by line.
columns
Views are eacked by column.
frameseq
Views are temporally interleaved.
Some examples follow:
# Convert left and right views into a frame sequential video.
ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
# Convert views into a side-by-side video with the same output resolution as the input.
ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
framestep
Select one frame every N-th frame.
This filter accepts the following option:
step
Select frame after every "step" frames. Allowed values are
positive integers higher than 0. Default value is 1.
frei0r
Apply a frei0r effect to the input video.
To enable compilation of this filter you need to install the frei0r
header and configure FFmpeg with "--enable-frei0r".
This filter accepts the following options:
filter_name
The name to the frei0r effect to load. If the environment variable
FREI0R_PATH is defined, the frei0r effect is searched in each one
of the directories specified by the colon separated list in
FREIOR_PATH, otherwise in the standard frei0r paths, which are in
this order: HOME/.frei0r-1/lib/, /usr/local/lib/frei0r-1/,
/usr/lib/frei0r-1/.
filter_params
A '|'-separated list of parameters to pass to the frei0r effect.
A frei0r effect parameter can be a boolean (whose values are specified
with "y" and "n"), a double, a color (specified by the syntax R/G/B,
(R, G, and B being float numbers from 0.0 to 1.0) or by a color
description specified in the "Color" section in the ffmpeg-utils
manual), a position (specified by the syntax X/Y, X and Y being float
numbers) and a string.
The number and kind of parameters depend on the loaded effect. If an
effect parameter is not specified the default value is set.
Examples
· Apply the distort0r effect, set the first two double parameters:
frei0r=filter_name=distort0r:filter_params=0.5|0.01
· Apply the colordistance effect, take a color as first parameter:
frei0r=colordistance:0.2/0.3/0.4
frei0r=colordistance:violet
frei0r=colordistance:0x112233
· Apply the perspective effect, specify the top left and top right
image positions:
frei0r=perspective:0.2/0.2|0.8/0.2
For more information see: <http://frei0r.dyne.org>
geq
The filter accepts the following options:
lum_expr, lum
Set the luminance expression.
cb_expr, cb
Set the chrominance blue expression.
cr_expr, cr
Set the chrominance red expression.
alpha_expr, a
Set the alpha expression.
red_expr, r
Set the red expression.
green_expr, g
Set the green expression.
blue_expr, b
Set the blue expression.
The colorspace is selected according to the specified options. If one
of the lum_expr, cb_expr, or cr_expr options is specified, the filter
will automatically select a YCbCr colorspace. If one of the red_expr,
green_expr, or blue_expr options is specified, it will select an RGB
colorspace.
If one of the chrominance expression is not defined, it falls back on
the other one. If no alpha expression is specified it will evaluate to
opaque value. If none of chrominance expressions are specified, they
will evaluate to the luminance expression.
The expressions can use the following variables and functions:
N The sequential number of the filtered frame, starting from 0.
X
Y The coordinates of the current sample.
W
H The width and height of the image.
SW
SH Width and height scale depending on the currently filtered plane.
It is the ratio between the corresponding luma plane number of
pixels and the current plane ones. E.g. for YUV4:2:0 the values are
"1,1" for the luma plane, and "0.5,0.5" for chroma planes.
T Time of the current frame, expressed in seconds.
p(x, y)
Return the value of the pixel at location (x,y) of the current
plane.
lum(x, y)
Return the value of the pixel at location (x,y) of the luminance
plane.
cb(x, y)
Return the value of the pixel at location (x,y) of the blue-
difference chroma plane. Return 0 if there is no such plane.
cr(x, y)
Return the value of the pixel at location (x,y) of the red-
difference chroma plane. Return 0 if there is no such plane.
r(x, y)
g(x, y)
b(x, y)
Return the value of the pixel at location (x,y) of the
red/green/blue component. Return 0 if there is no such component.
alpha(x, y)
Return the value of the pixel at location (x,y) of the alpha plane.
Return 0 if there is no such plane.
For functions, if x and y are outside the area, the value will be
automatically clipped to the closer edge.
Examples
· Flip the image horizontally:
geq=p(W-X\,Y)
· Generate a bidimensional sine wave, with angle "PI/3" and a
wavelength of 100 pixels:
geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
· Generate a fancy enigmatic moving light:
nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
· Generate a quick emboss effect:
format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
· Modify RGB components depending on pixel position:
geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
gradfun
Fix the banding artifacts that are sometimes introduced into nearly
flat regions by truncation to 8bit color depth. Interpolate the
gradients that should go where the bands are, and dither them.
This filter is designed for playback only. Do not use it prior to
lossy compression, because compression tends to lose the dither and
bring back the bands.
This filter accepts the following options:
strength
The maximum amount by which the filter will change any one pixel.
Also the threshold for detecting nearly flat regions. Acceptable
values range from .51 to 64, default value is 1.2, out-of-range
values will be clipped to the valid range.
radius
The neighborhood to fit the gradient to. A larger radius makes for
smoother gradients, but also prevents the filter from modifying the
pixels near detailed regions. Acceptable values are 8-32, default
value is 16, out-of-range values will be clipped to the valid
range.
Alternatively, the options can be specified as a flat string:
strength[:radius]
Examples
· Apply the filter with a 3.5 strength and radius of 8:
gradfun=3.5:8
· Specify radius, omitting the strength (which will fall-back to the
default value):
gradfun=radius=8
haldclut
Apply a Hald CLUT to a video stream.
First input is the video stream to process, and second one is the Hald
CLUT. The Hald CLUT input can be a simple picture or a complete video
stream.
The filter accepts the following options:
shortest
Force termination when the shortest input terminates. Default is 0.
repeatlast
Continue applying the last CLUT after the end of the stream. A
value of 0 disable the filter after the last frame of the CLUT is
reached. Default is 1.
"haldclut" also has the same interpolation options as lut3d (both
filters share the same internals).
More information about the Hald CLUT can be found on Eskil Steenberg's
website (Hald CLUT author) at
<http://www.quelsolaar.com/technology/clut.html>.
Workflow examples
Hald CLUT video stream
Generate an identity Hald CLUT stream altered with various effects:
ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut
Note: make sure you use a lossless codec.
Then use it with "haldclut" to apply it on some random stream:
ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
The Hald CLUT will be applied to the 10 first seconds (duration of
clut.nut), then the latest picture of that CLUT stream will be applied
to the remaining frames of the "mandelbrot" stream.
Hald CLUT with preview
A Hald CLUT is supposed to be a squared image of "Level*Level*Level" by
"Level*Level*Level" pixels. For a given Hald CLUT, FFmpeg will select
the biggest possible square starting at the top left of the picture.
The remaining padding pixels (bottom or right) will be ignored. This
area can be used to add a preview of the Hald CLUT.
Typically, the following generated Hald CLUT will be supported by the
"haldclut" filter:
ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "
pad=iw+320 [padded_clut];
smptebars=s=320x256, split [a][b];
[padded_clut][a] overlay=W-320:h, curves=color_negative [main];
[main][b] overlay=W-320" -frames:v 1 clut.png
It contains the original and a preview of the effect of the CLUT: SMPTE
color bars are displayed on the right-top, and below the same color
bars processed by the color changes.
Then, the effect of this Hald CLUT can be visualized with:
ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
hflip
Flip the input video horizontally.
For example to horizontally flip the input video with ffmpeg:
ffmpeg -i in.avi -vf "hflip" out.avi
histeq
This filter applies a global color histogram equalization on a per-
frame basis.
It can be used to correct video that has a compressed range of pixel
intensities. The filter redistributes the pixel intensities to
equalize their distribution across the intensity range. It may be
viewed as an "automatically adjusting contrast filter". This filter is
useful only for correcting degraded or poorly captured source video.
The filter accepts the following options:
strength
Determine the amount of equalization to be applied. As the
strength is reduced, the distribution of pixel intensities more-
and-more approaches that of the input frame. The value must be a
float number in the range [0,1] and defaults to 0.200.
intensity
Set the maximum intensity that can generated and scale the output
values appropriately. The strength should be set as desired and
then the intensity can be limited if needed to avoid washing-out.
The value must be a float number in the range [0,1] and defaults to
0.210.
antibanding
Set the antibanding level. If enabled the filter will randomly vary
the luminance of output pixels by a small amount to avoid banding
of the histogram. Possible values are "none", "weak" or "strong".
It defaults to "none".
histogram
Compute and draw a color distribution histogram for the input video.
The computed histogram is a representation of the color component
distribution in an image.
The filter accepts the following options:
mode
Set histogram mode.
It accepts the following values:
levels
Standard histogram that displays the color components
distribution in an image. Displays color graph for each color
component. Shows distribution of the Y, U, V, A or R, G, B
components, depending on input format, in the current frame.
Below each graph a color component scale meter is shown.
color
Displays chroma values (U/V color placement) in a two
dimensional graph (which is called a vectorscope). The brighter
a pixel in the vectorscope, the more pixels of the input frame
correspond to that pixel (i.e., more pixels have this chroma
value). The V component is displayed on the horizontal (X)
axis, with the leftmost side being V = 0 and the rightmost side
being V = 255. The U component is displayed on the vertical (Y)
axis, with the top representing U = 0 and the bottom
representing U = 255.
The position of a white pixel in the graph corresponds to the
chroma value of a pixel of the input clip. The graph can
therefore be used to read the hue (color flavor) and the
saturation (the dominance of the hue in the color). As the hue
of a color changes, it moves around the square. At the center
of the square the saturation is zero, which means that the
corresponding pixel has no color. If the amount of a specific
color is increased (while leaving the other colors unchanged)
the saturation increases, and the indicator moves towards the
edge of the square.
color2
Chroma values in vectorscope, similar as "color" but actual
chroma values are displayed.
waveform
Per row/column color component graph. In row mode, the graph on
the left side represents color component value 0 and the right
side represents value = 255. In column mode, the top side
represents color component value = 0 and bottom side represents
value = 255.
Default value is "levels".
level_height
Set height of level in "levels". Default value is 200. Allowed
range is [50, 2048].
scale_height
Set height of color scale in "levels". Default value is 12.
Allowed range is [0, 40].
step
Set step for "waveform" mode. Smaller values are useful to find out
how many values of the same luminance are distributed across input
rows/columns. Default value is 10. Allowed range is [1, 255].
waveform_mode
Set mode for "waveform". Can be either "row", or "column". Default
is "row".
waveform_mirror
Set mirroring mode for "waveform". 0 means unmirrored, 1 means
mirrored. In mirrored mode, higher values will be represented on
the left side for "row" mode and at the top for "column" mode.
Default is 0 (unmirrored).
display_mode
Set display mode for "waveform" and "levels". It accepts the
following values:
parade
Display separate graph for the color components side by side in
"row" waveform mode or one below the other in "column" waveform
mode for "waveform" histogram mode. For "levels" histogram
mode, per color component graphs are placed below each other.
Using this display mode in "waveform" histogram mode makes it
easy to spot color casts in the highlights and shadows of an
image, by comparing the contours of the top and the bottom
graphs of each waveform. Since whites, grays, and blacks are
characterized by exactly equal amounts of red, green, and blue,
neutral areas of the picture should display three waveforms of
roughly equal width/height. If not, the correction is easy to
perform by making level adjustments the three waveforms.
overlay
Presents information identical to that in the "parade", except
that the graphs representing color components are superimposed
directly over one another.
This display mode in "waveform" histogram mode makes it easier
to spot relative differences or similarities in overlapping
areas of the color components that are supposed to be
identical, such as neutral whites, grays, or blacks.
Default is "parade".
levels_mode
Set mode for "levels". Can be either "linear", or "logarithmic".
Default is "linear".
Examples
· Calculate and draw histogram:
ffplay -i input -vf histogram
hqdn3d
High precision/quality 3d denoise filter. This filter aims to reduce
image noise producing smooth images and making still images really
still. It should enhance compressibility.
It accepts the following optional parameters:
luma_spatial
a non-negative float number which specifies spatial luma strength,
defaults to 4.0
chroma_spatial
a non-negative float number which specifies spatial chroma
strength, defaults to 3.0*luma_spatial/4.0
luma_tmp
a float number which specifies luma temporal strength, defaults to
6.0*luma_spatial/4.0
chroma_tmp
a float number which specifies chroma temporal strength, defaults
to luma_tmp*chroma_spatial/luma_spatial
hue
Modify the hue and/or the saturation of the input.
This filter accepts the following options:
h Specify the hue angle as a number of degrees. It accepts an
expression, and defaults to "0".
s Specify the saturation in the [-10,10] range. It accepts an
expression and defaults to "1".
H Specify the hue angle as a number of radians. It accepts an
expression, and defaults to "0".
b Specify the brightness in the [-10,10] range. It accepts an
expression and defaults to "0".
h and H are mutually exclusive, and can't be specified at the same
time.
The b, h, H and s option values are expressions containing the
following constants:
n frame count of the input frame starting from 0
pts presentation timestamp of the input frame expressed in time base
units
r frame rate of the input video, NAN if the input frame rate is
unknown
t timestamp expressed in seconds, NAN if the input timestamp is
unknown
tb time base of the input video
Examples
· Set the hue to 90 degrees and the saturation to 1.0:
hue=h=90:s=1
· Same command but expressing the hue in radians:
hue=H=PI/2:s=1
· Rotate hue and make the saturation swing between 0 and 2 over a
period of 1 second:
hue="H=2*PI*t: s=sin(2*PI*t)+1"
· Apply a 3 seconds saturation fade-in effect starting at 0:
hue="s=min(t/3\,1)"
The general fade-in expression can be written as:
hue="s=min(0\, max((t-START)/DURATION\, 1))"
· Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
hue="s=max(0\, min(1\, (8-t)/3))"
The general fade-out expression can be written as:
hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
Commands
This filter supports the following commands:
b
s
h
H Modify the hue and/or the saturation and/or brightness of the input
video. The command accepts the same syntax of the corresponding
option.
If the specified expression is not valid, it is kept at its current
value.
idet
Detect video interlacing type.
This filter tries to detect if the input is interlaced or progressive,
top or bottom field first.
The filter accepts the following options:
intl_thres
Set interlacing threshold.
prog_thres
Set progressive threshold.
il
Deinterleave or interleave fields.
This filter allows one to process interlaced images fields without
deinterlacing them. Deinterleaving splits the input frame into 2 fields
(so called half pictures). Odd lines are moved to the top half of the
output image, even lines to the bottom half. You can process (filter)
them independently and then re-interleave them.
The filter accepts the following options:
luma_mode, l
chroma_mode, c
alpha_mode, a
Available values for luma_mode, chroma_mode and alpha_mode are:
none
Do nothing.
deinterleave, d
Deinterleave fields, placing one above the other.
interleave, i
Interleave fields. Reverse the effect of deinterleaving.
Default value is "none".
luma_swap, ls
chroma_swap, cs
alpha_swap, as
Swap luma/chroma/alpha fields. Exchange even & odd lines. Default
value is 0.
interlace
Simple interlacing filter from progressive contents. This interleaves
upper (or lower) lines from odd frames with lower (or upper) lines from
even frames, halving the frame rate and preserving image height. A
vertical lowpass filter is always applied in order to avoid twitter
effects and reduce moire patterns.
Original Original New Frame
Frame 'j' Frame 'j+1' (tff)
========== =========== ==================
Line 0 --------------------> Frame 'j' Line 0
Line 1 Line 1 ----> Frame 'j+1' Line 1
Line 2 ---------------------> Frame 'j' Line 2
Line 3 Line 3 ----> Frame 'j+1' Line 3
... ... ...
New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
It accepts the following optional parameters:
scan
determines whether the interlaced frame is taken from the even (tff
- default) or odd (bff) lines of the progressive frame.
kerndeint
Deinterlace input video by applying Donald Graft's adaptive kernel
deinterling. Work on interlaced parts of a video to produce progressive
frames.
The description of the accepted parameters follows.
thresh
Set the threshold which affects the filter's tolerance when
determining if a pixel line must be processed. It must be an
integer in the range [0,255] and defaults to 10. A value of 0 will
result in applying the process on every pixels.
map Paint pixels exceeding the threshold value to white if set to 1.
Default is 0.
order
Set the fields order. Swap fields if set to 1, leave fields alone
if 0. Default is 0.
sharp
Enable additional sharpening if set to 1. Default is 0.
twoway
Enable twoway sharpening if set to 1. Default is 0.
Examples
· Apply default values:
kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
· Enable additional sharpening:
kerndeint=sharp=1
· Paint processed pixels in white:
kerndeint=map=1
lut3d
Apply a 3D LUT to an input video.
The filter accepts the following options:
file
Set the 3D LUT file name.
Currently supported formats:
3dl AfterEffects
cube
Iridas
dat DaVinci
m3d Pandora
interp
Select interpolation mode.
Available values are:
nearest
Use values from the nearest defined point.
trilinear
Interpolate values using the 8 points defining a cube.
tetrahedral
Interpolate values using a tetrahedron.
lut, lutrgb, lutyuv
Compute a look-up table for binding each pixel component input value to
an output value, and apply it to input video.
lutyuv applies a lookup table to a YUV input video, lutrgb to an RGB
input video.
These filters accept the following options:
c0 set first pixel component expression
c1 set second pixel component expression
c2 set third pixel component expression
c3 set fourth pixel component expression, corresponds to the alpha
component
r set red component expression
g set green component expression
b set blue component expression
a alpha component expression
y set Y/luminance component expression
u set U/Cb component expression
v set V/Cr component expression
Each of them specifies the expression to use for computing the lookup
table for the corresponding pixel component values.
The exact component associated to each of the c* options depends on the
format in input.
The lut filter requires either YUV or RGB pixel formats in input,
lutrgb requires RGB pixel formats in input, and lutyuv requires YUV.
The expressions can contain the following constants and functions:
w
h the input width and height
val input value for the pixel component
clipval
the input value clipped in the minval-maxval range
maxval
maximum value for the pixel component
minval
minimum value for the pixel component
negval
the negated value for the pixel component value clipped in the
minval-maxval range , it corresponds to the expression
"maxval-clipval+minval"
clip(val)
the computed value in val clipped in the minval-maxval range
gammaval(gamma)
the computed gamma correction value of the pixel component value
clipped in the minval-maxval range, corresponds to the expression
"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
All expressions default to "val".
Examples
· Negate input video:
lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
The above is the same as:
lutrgb="r=negval:g=negval:b=negval"
lutyuv="y=negval:u=negval:v=negval"
· Negate luminance:
lutyuv=y=negval
· Remove chroma components, turns the video into a graytone image:
lutyuv="u=128:v=128"
· Apply a luma burning effect:
lutyuv="y=2*val"
· Remove green and blue components:
lutrgb="g=0:b=0"
· Set a constant alpha channel value on input:
format=rgba,lutrgb=a="maxval-minval/2"
· Correct luminance gamma by a 0.5 factor:
lutyuv=y=gammaval(0.5)
· Discard least significant bits of luma:
lutyuv=y='bitand(val, 128+64+32)'
mergeplanes
Merge color channel components from several video streams.
The filter accepts up to 4 input streams, and merge selected input
planes to the output video.
This filter accepts the following options:
mapping
Set input to output plane mapping. Default is 0.
The mappings is specified as a bitmap. It should be specified as a
hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
mapping for the first plane of the output stream. 'A' sets the
number of the input stream to use (from 0 to 3), and 'a' the plane
number of the corresponding input to use (from 0 to 3). The rest of
the mappings is similar, 'Bb' describes the mapping for the output
stream second plane, 'Cc' describes the mapping for the output
stream third plane and 'Dd' describes the mapping for the output
stream fourth plane.
format
Set output pixel format. Default is "yuva444p".
Examples
· Merge three gray video streams of same width and height into single
video stream:
[a0][a1][a2]mergeplanes=0x001020:yuv444p
· Merge 1st yuv444p stream and 2nd gray video stream into yuva444p
video stream:
[a0][a1]mergeplanes=0x00010210:yuva444p
· Swap Y and A plane in yuva444p stream:
format=yuva444p,mergeplanes=0x03010200:yuva444p
· Swap U and V plane in yuv420p stream:
format=yuv420p,mergeplanes=0x000201:yuv420p
· Cast a rgb24 clip to yuv444p:
format=rgb24,mergeplanes=0x000102:yuv444p
mcdeint
Apply motion-compensation deinterlacing.
It needs one field per frame as input and must thus be used together
with yadif=1/3 or equivalent.
This filter accepts the following options:
mode
Set the deinterlacing mode.
It accepts one of the following values:
fast
medium
slow
use iterative motion estimation
extra_slow
like slow, but use multiple reference frames.
Default value is fast.
parity
Set the picture field parity assumed for the input video. It must
be one of the following values:
0, tff
assume top field first
1, bff
assume bottom field first
Default value is bff.
qp Set per-block quantization parameter (QP) used by the internal
encoder.
Higher values should result in a smoother motion vector field but
less optimal individual vectors. Default value is 1.
mp
Apply an MPlayer filter to the input video.
This filter provides a wrapper around some of the filters of
MPlayer/MEncoder.
This wrapper is considered experimental. Some of the wrapped filters
may not work properly and we may drop support for them, as they will be
implemented natively into FFmpeg. Thus you should avoid depending on
them when writing portable scripts.
The filter accepts the parameters: filter_name[:=]filter_params
filter_name is the name of a supported MPlayer filter, filter_params is
a string containing the parameters accepted by the named filter.
The list of the currently supported filters follows:
eq2
eq
fspp
ilpack
pp7
softpulldown
uspp
The parameter syntax and behavior for the listed filters are the same
of the corresponding MPlayer filters. For detailed instructions check
the "VIDEO FILTERS" section in the MPlayer manual.
Examples
· Adjust gamma, brightness, contrast:
mp=eq2=1.0:2:0.5
See also mplayer(1), <http://www.mplayerhq.hu/>.
mpdecimate
Drop frames that do not differ greatly from the previous frame in order
to reduce frame rate.
The main use of this filter is for very-low-bitrate encoding (e.g.
streaming over dialup modem), but it could in theory be used for fixing
movies that were inverse-telecined incorrectly.
A description of the accepted options follows.
max Set the maximum number of consecutive frames which can be dropped
(if positive), or the minimum interval between dropped frames (if
negative). If the value is 0, the frame is dropped unregarding the
number of previous sequentially dropped frames.
Default value is 0.
hi
lo
frac
Set the dropping threshold values.
Values for hi and lo are for 8x8 pixel blocks and represent actual
pixel value differences, so a threshold of 64 corresponds to 1 unit
of difference for each pixel, or the same spread out differently
over the block.
A frame is a candidate for dropping if no 8x8 blocks differ by more
than a threshold of hi, and if no more than frac blocks (1 meaning
the whole image) differ by more than a threshold of lo.
Default value for hi is 64*12, default value for lo is 64*5, and
default value for frac is 0.33.
negate
Negate input video.
This filter accepts an integer in input, if non-zero it negates the
alpha component (if available). The default value in input is 0.
noformat
Force libavfilter not to use any of the specified pixel formats for the
input to the next filter.
This filter accepts the following parameters:
pix_fmts
A '|'-separated list of pixel format names, for example
"pix_fmts=yuv420p|monow|rgb24".
Examples
· Force libavfilter to use a format different from yuv420p for the
input to the vflip filter:
noformat=pix_fmts=yuv420p,vflip
· Convert the input video to any of the formats not contained in the
list:
noformat=yuv420p|yuv444p|yuv410p
noise
Add noise on video input frame.
The filter accepts the following options:
all_seed
c0_seed
c1_seed
c2_seed
c3_seed
Set noise seed for specific pixel component or all pixel components
in case of all_seed. Default value is 123457.
all_strength, alls
c0_strength, c0s
c1_strength, c1s
c2_strength, c2s
c3_strength, c3s
Set noise strength for specific pixel component or all pixel
components in case all_strength. Default value is 0. Allowed range
is [0, 100].
all_flags, allf
c0_flags, c0f
c1_flags, c1f
c2_flags, c2f
c3_flags, c3f
Set pixel component flags or set flags for all components if
all_flags. Available values for component flags are:
a averaged temporal noise (smoother)
p mix random noise with a (semi)regular pattern
t temporal noise (noise pattern changes between frames)
u uniform noise (gaussian otherwise)
Examples
Add temporal and uniform noise to input video:
noise=alls=20:allf=t+u
null
Pass the video source unchanged to the output.
ocv
Apply video transform using libopencv.
To enable this filter install libopencv library and headers and
configure FFmpeg with "--enable-libopencv".
This filter accepts the following parameters:
filter_name
The name of the libopencv filter to apply.
filter_params
The parameters to pass to the libopencv filter. If not specified
the default values are assumed.
Refer to the official libopencv documentation for more precise
information:
<http://opencv.willowgarage.com/documentation/c/image_filtering.html>
Follows the list of supported libopencv filters.
dilate
Dilate an image by using a specific structuring element. This filter
corresponds to the libopencv function "cvDilate".
It accepts the parameters: struct_el|nb_iterations.
struct_el represents a structuring element, and has the syntax:
colsxrows+anchor_xxanchor_y/shape
cols and rows represent the number of columns and rows of the
structuring element, anchor_x and anchor_y the anchor point, and shape
the shape for the structuring element, and can be one of the values
"rect", "cross", "ellipse", "custom".
If the value for shape is "custom", it must be followed by a string of
the form "=filename". The file with name filename is assumed to
represent a binary image, with each printable character corresponding
to a bright pixel. When a custom shape is used, cols and rows are
ignored, the number or columns and rows of the read file are assumed
instead.
The default value for struct_el is "3x3+0x0/rect".
nb_iterations specifies the number of times the transform is applied to
the image, and defaults to 1.
Follow some example:
# use the default values
ocv=dilate
# dilate using a structuring element with a 5x5 cross, iterate two times
ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
# read the shape from the file diamond.shape, iterate two times
# the file diamond.shape may contain a pattern of characters like this:
# *
# ***
# *****
# ***
# *
# the specified cols and rows are ignored (but not the anchor point coordinates)
ocv=dilate:0x0+2x2/custom=diamond.shape|2
erode
Erode an image by using a specific structuring element. This filter
corresponds to the libopencv function "cvErode".
The filter accepts the parameters: struct_el:nb_iterations, with the
same syntax and semantics as the dilate filter.
smooth
Smooth the input video.
The filter takes the following parameters:
type|param1|param2|param3|param4.
type is the type of smooth filter to apply, and can be one of the
following values: "blur", "blur_no_scale", "median", "gaussian",
"bilateral". The default value is "gaussian".
param1, param2, param3, and param4 are parameters whose meanings depend
on smooth type. param1 and param2 accept integer positive values or 0,
param3 and param4 accept float values.
The default value for param1 is 3, the default value for the other
parameters is 0.
These parameters correspond to the parameters assigned to the libopencv
function "cvSmooth".
overlay
Overlay one video on top of another.
It takes two inputs and one output, the first input is the "main" video
on which the second input is overlayed.
This filter accepts the following parameters:
A description of the accepted options follows.
x
y Set the expression for the x and y coordinates of the overlayed
video on the main video. Default value is "0" for both expressions.
In case the expression is invalid, it is set to a huge value
(meaning that the overlay will not be displayed within the output
visible area).
eof_action
The action to take when EOF is encountered on the secondary input,
accepts one of the following values:
repeat
repeat the last frame (the default)
endall
end both streams
pass
pass through the main input
eval
Set when the expressions for x, and y are evaluated.
It accepts the following values:
init
only evaluate expressions once during the filter initialization
or when a command is processed
frame
evaluate expressions for each incoming frame
Default value is frame.
shortest
If set to 1, force the output to terminate when the shortest input
terminates. Default value is 0.
format
Set the format for the output video.
It accepts the following values:
yuv420
force YUV420 output
yuv422
force YUV422 output
yuv444
force YUV444 output
rgb force RGB output
Default value is yuv420.
rgb (deprecated)
If set to 1, force the filter to accept inputs in the RGB color
space. Default value is 0. This option is deprecated, use format
instead.
repeatlast
If set to 1, force the filter to draw the last overlay frame over
the main input until the end of the stream. A value of 0 disables
this behavior. Default value is 1.
The x, and y expressions can contain the following parameters.
main_w, W
main_h, H
main input width and height
overlay_w, w
overlay_h, h
overlay input width and height
x
y the computed values for x and y. They are evaluated for each new
frame.
hsub
vsub
horizontal and vertical chroma subsample values of the output
format. For example for the pixel format "yuv422p" hsub is 2 and
vsub is 1.
n the number of input frame, starting from 0
pos the position in the file of the input frame, NAN if unknown
t timestamp expressed in seconds, NAN if the input timestamp is
unknown
Note that the n, pos, t variables are available only when evaluation is
done per frame, and will evaluate to NAN when eval is set to init.
Be aware that frames are taken from each input video in timestamp
order, hence, if their initial timestamps differ, it is a good idea to
pass the two inputs through a setpts=PTS-STARTPTS filter to have them
begin in the same zero timestamp, as it does the example for the movie
filter.
You can chain together more overlays but you should test the efficiency
of such approach.
Commands
This filter supports the following commands:
x
y Modify the x and y of the overlay input. The command accepts the
same syntax of the corresponding option.
If the specified expression is not valid, it is kept at its current
value.
Examples
· Draw the overlay at 10 pixels from the bottom right corner of the
main video:
overlay=main_w-overlay_w-10:main_h-overlay_h-10
Using named options the example above becomes:
overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
· Insert a transparent PNG logo in the bottom left corner of the
input, using the ffmpeg tool with the "-filter_complex" option:
ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
· Insert 2 different transparent PNG logos (second logo on bottom
right corner) using the ffmpeg tool:
ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
· Add a transparent color layer on top of the main video, "WxH" must
specify the size of the main input to the overlay filter:
color=color=red@.3:size=WxH [over]; [in][over] overlay [out]
· Play an original video and a filtered version (here with the
deshake filter) side by side using the ffplay tool:
ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
The above command is the same as:
ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
· Make a sliding overlay appearing from the left to the right top
part of the screen starting since time 2:
overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
· Compose output by putting two input videos side to side:
ffmpeg -i left.avi -i right.avi -filter_complex "
nullsrc=size=200x100 [background];
[0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
[1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
[background][left] overlay=shortest=1 [background+left];
[background+left][right] overlay=shortest=1:x=100 [left+right]
"
· mask 10-20 seconds of a video by applying the delogo filter to a
section
ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
-vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
masked.avi
· Chain several overlays in cascade:
nullsrc=s=200x200 [bg];
testsrc=s=100x100, split=4 [in0][in1][in2][in3];
[in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
[in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
[in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
[in3] null, [mid2] overlay=100:100 [out0]
owdenoise
Apply Overcomplete Wavelet denoiser.
The filter accepts the following options:
depth
Set depth.
Larger depth values will denoise lower frequency components more,
but slow down filtering.
Must be an int in the range 8-16, default is 8.
luma_strength, ls
Set luma strength.
Must be a double value in the range 0-1000, default is 1.0.
chroma_strength, cs
Set chroma strength.
Must be a double value in the range 0-1000, default is 1.0.
pad
Add paddings to the input image, and place the original input at the
given coordinates x, y.
This filter accepts the following parameters:
width, w
height, h
Specify an expression for the size of the output image with the
paddings added. If the value for width or height is 0, the
corresponding input size is used for the output.
The width expression can reference the value set by the height
expression, and vice versa.
The default value of width and height is 0.
x
y Specify an expression for the offsets where to place the input
image in the padded area with respect to the top/left border of the
output image.
The x expression can reference the value set by the y expression,
and vice versa.
The default value of x and y is 0.
color
Specify the color of the padded area. For the syntax of this
option, check the "Color" section in the ffmpeg-utils manual.
The default value of color is "black".
The value for the width, height, x, and y options are expressions
containing the following constants:
in_w
in_h
the input video width and height
iw
ih same as in_w and in_h
out_w
out_h
the output width and height, that is the size of the padded area as
specified by the width and height expressions
ow
oh same as out_w and out_h
x
y x and y offsets as specified by the x and y expressions, or NAN if
not yet specified
a same as iw / ih
sar input sample aspect ratio
dar input display aspect ratio, it is the same as (iw / ih) * sar
hsub
vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
Examples
· Add paddings with color "violet" to the input video. Output video
size is 640x480, the top-left corner of the input video is placed
at column 0, row 40:
pad=640:480:0:40:violet
The example above is equivalent to the following command:
pad=width=640:height=480:x=0:y=40:color=violet
· Pad the input to get an output with dimensions increased by 3/2,
and put the input video at the center of the padded area:
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
· Pad the input to get a squared output with size equal to the
maximum value between the input width and height, and put the input
video at the center of the padded area:
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
· Pad the input to get a final w/h ratio of 16:9:
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
· In case of anamorphic video, in order to set the output display
aspect correctly, it is necessary to use sar in the expression,
according to the relation:
(ih * X / ih) * sar = output_dar
X = output_dar / sar
Thus the previous example needs to be modified to:
pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
· Double output size and put the input video in the bottom-right
corner of the output padded area:
pad="2*iw:2*ih:ow-iw:oh-ih"
perspective
Correct perspective of video not recorded perpendicular to the screen.
A description of the accepted parameters follows.
x0
y0
x1
y1
x2
y2
x3
y3 Set coordinates expression for top left, top right, bottom left and
bottom right corners. Default values are "0:0:W:0:0:H:W:H" with
which perspective will remain unchanged.
The expressions can use the following variables:
W
H the width and height of video frame.
interpolation
Set interpolation for perspective correction.
It accepts the following values:
linear
cubic
Default value is linear.
phase
Delay interlaced video by one field time so that the field order
changes.
The intended use is to fix PAL movies that have been captured with the
opposite field order to the film-to-video transfer.
A description of the accepted parameters follows.
mode
Set phase mode.
It accepts the following values:
t Capture field order top-first, transfer bottom-first. Filter
will delay the bottom field.
b Capture field order bottom-first, transfer top-first. Filter
will delay the top field.
p Capture and transfer with the same field order. This mode only
exists for the documentation of the other options to refer to,
but if you actually select it, the filter will faithfully do
nothing.
a Capture field order determined automatically by field flags,
transfer opposite. Filter selects among t and b modes on a
frame by frame basis using field flags. If no field information
is available, then this works just like u.
u Capture unknown or varying, transfer opposite. Filter selects
among t and b on a frame by frame basis by analyzing the images
and selecting the alternative that produces best match between
the fields.
T Capture top-first, transfer unknown or varying. Filter selects
among t and p using image analysis.
B Capture bottom-first, transfer unknown or varying. Filter
selects among b and p using image analysis.
A Capture determined by field flags, transfer unknown or varying.
Filter selects among t, b and p using field flags and image
analysis. If no field information is available, then this works
just like U. This is the default mode.
U Both capture and transfer unknown or varying. Filter selects
among t, b and p using image analysis only.
pixdesctest
Pixel format descriptor test filter, mainly useful for internal
testing. The output video should be equal to the input video.
For example:
format=monow, pixdesctest
can be used to test the monowhite pixel format descriptor definition.
pp
Enable the specified chain of postprocessing subfilters using
libpostproc. This library should be automatically selected with a GPL
build ("--enable-gpl"). Subfilters must be separated by '/' and can be
disabled by prepending a '-'. Each subfilter and some options have a
short and a long name that can be used interchangeably, i.e. dr/dering
are the same.
The filters accept the following options:
subfilters
Set postprocessing subfilters string.
All subfilters share common options to determine their scope:
a/autoq
Honor the quality commands for this subfilter.
c/chrom
Do chrominance filtering, too (default).
y/nochrom
Do luminance filtering only (no chrominance).
n/noluma
Do chrominance filtering only (no luminance).
These options can be appended after the subfilter name, separated by a
'|'.
Available subfilters are:
hb/hdeblock[|difference[|flatness]]
Horizontal deblocking filter
difference
Difference factor where higher values mean more deblocking
(default: 32).
flatness
Flatness threshold where lower values mean more deblocking
(default: 39).
vb/vdeblock[|difference[|flatness]]
Vertical deblocking filter
difference
Difference factor where higher values mean more deblocking
(default: 32).
flatness
Flatness threshold where lower values mean more deblocking
(default: 39).
ha/hadeblock[|difference[|flatness]]
Accurate horizontal deblocking filter
difference
Difference factor where higher values mean more deblocking
(default: 32).
flatness
Flatness threshold where lower values mean more deblocking
(default: 39).
va/vadeblock[|difference[|flatness]]
Accurate vertical deblocking filter
difference
Difference factor where higher values mean more deblocking
(default: 32).
flatness
Flatness threshold where lower values mean more deblocking
(default: 39).
The horizontal and vertical deblocking filters share the difference and
flatness values so you cannot set different horizontal and vertical
thresholds.
h1/x1hdeblock
Experimental horizontal deblocking filter
v1/x1vdeblock
Experimental vertical deblocking filter
dr/dering
Deringing filter
tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise
reducer
threshold1
larger -> stronger filtering
threshold2
larger -> stronger filtering
threshold3
larger -> stronger filtering
al/autolevels[:f/fullyrange], automatic brightness / contrast
correction
f/fullyrange
Stretch luminance to "0-255".
lb/linblenddeint
Linear blend deinterlacing filter that deinterlaces the given block
by filtering all lines with a "(1 2 1)" filter.
li/linipoldeint
Linear interpolating deinterlacing filter that deinterlaces the
given block by linearly interpolating every second line.
ci/cubicipoldeint
Cubic interpolating deinterlacing filter deinterlaces the given
block by cubically interpolating every second line.
md/mediandeint
Median deinterlacing filter that deinterlaces the given block by
applying a median filter to every second line.
fd/ffmpegdeint
FFmpeg deinterlacing filter that deinterlaces the given block by
filtering every second line with a "(-1 4 2 4 -1)" filter.
l5/lowpass5
Vertically applied FIR lowpass deinterlacing filter that
deinterlaces the given block by filtering all lines with a "(-1 2 6
2 -1)" filter.
fq/forceQuant[|quantizer]
Overrides the quantizer table from the input with the constant
quantizer you specify.
quantizer
Quantizer to use
de/default
Default pp filter combination ("hb|a,vb|a,dr|a")
fa/fast
Fast pp filter combination ("h1|a,v1|a,dr|a")
ac High quality pp filter combination ("ha|a|128|7,va|a,dr|a")
Examples
· Apply horizontal and vertical deblocking, deringing and automatic
brightness/contrast:
pp=hb/vb/dr/al
· Apply default filters without brightness/contrast correction:
pp=de/-al
· Apply default filters and temporal denoiser:
pp=default/tmpnoise|1|2|3
· Apply deblocking on luminance only, and switch vertical deblocking
on or off automatically depending on available CPU time:
pp=hb|y/vb|a
psnr
Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
Ratio) between two input videos.
This filter takes in input two input videos, the first input is
considered the "main" source and is passed unchanged to the output. The
second input is used as a "reference" video for computing the PSNR.
Both video inputs must have the same resolution and pixel format for
this filter to work correctly. Also it assumes that both inputs have
the same number of frames, which are compared one by one.
The obtained average PSNR is printed through the logging system.
The filter stores the accumulated MSE (mean squared error) of each
frame, and at the end of the processing it is averaged across all
frames equally, and the following formula is applied to obtain the
PSNR:
PSNR = 10*log10(MAX^2/MSE)
Where MAX is the average of the maximum values of each component of the
image.
The description of the accepted parameters follows.
stats_file, f
If specified the filter will use the named file to save the PSNR of
each individual frame.
The file printed if stats_file is selected, contains a sequence of
key/value pairs of the form key:value for each compared couple of
frames.
A description of each shown parameter follows:
n sequential number of the input frame, starting from 1
mse_avg
Mean Square Error pixel-by-pixel average difference of the compared
frames, averaged over all the image components.
mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
Mean Square Error pixel-by-pixel average difference of the compared
frames for the component specified by the suffix.
psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
Peak Signal to Noise ratio of the compared frames for the component
specified by the suffix.
For example:
movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
[main][ref] psnr="stats_file=stats.log" [out]
On this example the input file being processed is compared with the
reference file ref_movie.mpg. The PSNR of each individual frame is
stored in stats.log.
pullup
Pulldown reversal (inverse telecine) filter, capable of handling mixed
hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps
progressive content.
The pullup filter is designed to take advantage of future context in
making its decisions. This filter is stateless in the sense that it
does not lock onto a pattern to follow, but it instead looks forward to
the following fields in order to identify matches and rebuild
progressive frames.
To produce content with an even framerate, insert the fps filter after
pullup, use "fps=24000/1001" if the input frame rate is 29.97fps,
"fps=24" for 30fps and the (rare) telecined 25fps input.
The filter accepts the following options:
jl
jr
jt
jb These options set the amount of "junk" to ignore at the left,
right, top, and bottom of the image, respectively. Left and right
are in units of 8 pixels, while top and bottom are in units of 2
lines. The default is 8 pixels on each side.
sb Set the strict breaks. Setting this option to 1 will reduce the
chances of filter generating an occasional mismatched frame, but it
may also cause an excessive number of frames to be dropped during
high motion sequences. Conversely, setting it to -1 will make
filter match fields more easily. This may help processing of video
where there is slight blurring between the fields, but may also
cause there to be interlaced frames in the output. Default value
is 0.
mp Set the metric plane to use. It accepts the following values:
l Use luma plane.
u Use chroma blue plane.
v Use chroma red plane.
This option may be set to use chroma plane instead of the default
luma plane for doing filter's computations. This may improve
accuracy on very clean source material, but more likely will
decrease accuracy, especially if there is chroma noise (rainbow
effect) or any grayscale video. The main purpose of setting mp to
a chroma plane is to reduce CPU load and make pullup usable in
realtime on slow machines.
For best results (without duplicated frames in the output file) it is
necessary to change the output frame rate. For example, to inverse
telecine NTSC input:
ffmpeg -i input -vf pullup -r 24000/1001 ...
removelogo
Suppress a TV station logo, using an image file to determine which
pixels comprise the logo. It works by filling in the pixels that
comprise the logo with neighboring pixels.
The filter accepts the following options:
filename, f
Set the filter bitmap file, which can be any image format supported
by libavformat. The width and height of the image file must match
those of the video stream being processed.
Pixels in the provided bitmap image with a value of zero are not
considered part of the logo, non-zero pixels are considered part of the
logo. If you use white (255) for the logo and black (0) for the rest,
you will be safe. For making the filter bitmap, it is recommended to
take a screen capture of a black frame with the logo visible, and then
using a threshold filter followed by the erode filter once or twice.
If needed, little splotches can be fixed manually. Remember that if
logo pixels are not covered, the filter quality will be much reduced.
Marking too many pixels as part of the logo does not hurt as much, but
it will increase the amount of blurring needed to cover over the image
and will destroy more information than necessary, and extra pixels will
slow things down on a large logo.
rotate
Rotate video by an arbitrary angle expressed in radians.
The filter accepts the following options:
A description of the optional parameters follows.
angle, a
Set an expression for the angle by which to rotate the input video
clockwise, expressed as a number of radians. A negative value will
result in a counter-clockwise rotation. By default it is set to
"0".
This expression is evaluated for each frame.
out_w, ow
Set the output width expression, default value is "iw". This
expression is evaluated just once during configuration.
out_h, oh
Set the output height expression, default value is "ih". This
expression is evaluated just once during configuration.
bilinear
Enable bilinear interpolation if set to 1, a value of 0 disables
it. Default value is 1.
fillcolor, c
Set the color used to fill the output area not covered by the
rotated image. For the generalsyntax of this option, check the
"Color" section in the ffmpeg-utils manual. If the special value
"none" is selected then no background is printed (useful for
example if the background is never shown).
Default value is "black".
The expressions for the angle and the output size can contain the
following constants and functions:
n sequential number of the input frame, starting from 0. It is always
NAN before the first frame is filtered.
t time in seconds of the input frame, it is set to 0 when the filter
is configured. It is always NAN before the first frame is filtered.
hsub
vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
in_w, iw
in_h, ih
the input video width and height
out_w, ow
out_h, oh
the output width and height, that is the size of the padded area as
specified by the width and height expressions
rotw(a)roth(a)
the minimal width/height required for completely containing the
input video rotated by a radians.
These are only available when computing the out_w and out_h
expressions.
Examples
· Rotate the input by PI/6 radians clockwise:
rotate=PI/6
· Rotate the input by PI/6 radians counter-clockwise:
rotate=-PI/6
· Rotate the input by 45 degrees clockwise:
rotate=45*PI/180
· Apply a constant rotation with period T, starting from an angle of
PI/3:
rotate=PI/3+2*PI*t/T
· Make the input video rotation oscillating with a period of T
seconds and an amplitude of A radians:
rotate=A*sin(2*PI/T*t)
· Rotate the video, output size is chosen so that the whole rotating
input video is always completely contained in the output:
rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
· Rotate the video, reduce the output size so that no background is
ever shown:
rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
Commands
The filter supports the following commands:
a, angle
Set the angle expression. The command accepts the same syntax of
the corresponding option.
If the specified expression is not valid, it is kept at its current
value.
sab
Apply Shape Adaptive Blur.
The filter accepts the following options:
luma_radius, lr
Set luma blur filter strength, must be a value in range 0.1-4.0,
default value is 1.0. A greater value will result in a more blurred
image, and in slower processing.
luma_pre_filter_radius, lpfr
Set luma pre-filter radius, must be a value in the 0.1-2.0 range,
default value is 1.0.
luma_strength, ls
Set luma maximum difference between pixels to still be considered,
must be a value in the 0.1-100.0 range, default value is 1.0.
chroma_radius, cr
Set chroma blur filter strength, must be a value in range 0.1-4.0.
A greater value will result in a more blurred image, and in slower
processing.
chroma_pre_filter_radius, cpfr
Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
chroma_strength, cs
Set chroma maximum difference between pixels to still be
considered, must be a value in the 0.1-100.0 range.
Each chroma option value, if not explicitly specified, is set to the
corresponding luma option value.
scale
Scale (resize) the input video, using the libswscale library.
The scale filter forces the output display aspect ratio to be the same
of the input, by changing the output sample aspect ratio.
If the input image format is different from the format requested by the
next filter, the scale filter will convert the input to the requested
format.
Options
The filter accepts the following options, or any of the options
supported by the libswscale scaler.
See the ffmpeg-scaler manual for the complete list of scaler options.
width, w
height, h
Set the output video dimension expression. Default value is the
input dimension.
If the value is 0, the input width is used for the output.
If one of the values is -1, the scale filter will use a value that
maintains the aspect ratio of the input image, calculated from the
other specified dimension. If both of them are -1, the input size
is used
If one of the values is -n with n > 1, the scale filter will also
use a value that maintains the aspect ratio of the input image,
calculated from the other specified dimension. After that it will,
however, make sure that the calculated dimension is divisible by n
and adjust the value if necessary.
See below for the list of accepted constants for use in the
dimension expression.
interl
Set the interlacing mode. It accepts the following values:
1 Force interlaced aware scaling.
0 Do not apply interlaced scaling.
-1 Select interlaced aware scaling depending on whether the source
frames are flagged as interlaced or not.
Default value is 0.
flags
Set libswscale scaling flags. See the ffmpeg-scaler manual for the
complete list of values. If not explicitly specified the filter
applies the default flags.
size, s
Set the video size. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual.
in_color_matrix
out_color_matrix
Set in/output YCbCr color space type.
This allows the autodetected value to be overridden as well as
allows forcing a specific value used for the output and encoder.
If not specified, the color space type depends on the pixel format.
Possible values:
auto
Choose automatically.
bt709
Format conforming to International Telecommunication Union
(ITU) Recommendation BT.709.
fcc Set color space conforming to the United States Federal
Communications Commission (FCC) Code of Federal Regulations
(CFR) Title 47 (2003) 73.682 (a).
bt601
Set color space conforming to:
· ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
· ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
· Society of Motion Picture and Television Engineers (SMPTE)
ST 170:2004
smpte240m
Set color space conforming to SMPTE ST 240:1999.
in_range
out_range
Set in/output YCbCr sample range.
This allows the autodetected value to be overridden as well as
allows forcing a specific value used for the output and encoder. If
not specified, the range depends on the pixel format. Possible
values:
auto
Choose automatically.
jpeg/full/pc
Set full range (0-255 in case of 8-bit luma).
mpeg/tv
Set "MPEG" range (16-235 in case of 8-bit luma).
force_original_aspect_ratio
Enable decreasing or increasing output video width or height if
necessary to keep the original aspect ratio. Possible values:
disable
Scale the video as specified and disable this feature.
decrease
The output video dimensions will automatically be decreased if
needed.
increase
The output video dimensions will automatically be increased if
needed.
One useful instance of this option is that when you know a specific
device's maximum allowed resolution, you can use this to limit the
output video to that, while retaining the aspect ratio. For
example, device A allows 1280x720 playback, and your video is
1920x800. Using this option (set it to decrease) and specifying
1280x720 to the command line makes the output 1280x533.
Please note that this is a different thing than specifying -1 for w
or h, you still need to specify the output resolution for this
option to work.
The values of the w and h options are expressions containing the
following constants:
in_w
in_h
the input width and height
iw
ih same as in_w and in_h
out_w
out_h
the output (scaled) width and height
ow
oh same as out_w and out_h
a same as iw / ih
sar input sample aspect ratio
dar input display aspect ratio. Calculated from "(iw / ih) * sar".
hsub
vsub
horizontal and vertical input chroma subsample values. For example
for the pixel format "yuv422p" hsub is 2 and vsub is 1.
ohsub
ovsub
horizontal and vertical output chroma subsample values. For example
for the pixel format "yuv422p" hsub is 2 and vsub is 1.
Examples
· Scale the input video to a size of 200x100:
scale=w=200:h=100
This is equivalent to:
scale=200:100
or:
scale=200x100
· Specify a size abbreviation for the output size:
scale=qcif
which can also be written as:
scale=size=qcif
· Scale the input to 2x:
scale=w=2*iw:h=2*ih
· The above is the same as:
scale=2*in_w:2*in_h
· Scale the input to 2x with forced interlaced scaling:
scale=2*iw:2*ih:interl=1
· Scale the input to half size:
scale=w=iw/2:h=ih/2
· Increase the width, and set the height to the same size:
scale=3/2*iw:ow
· Seek for Greek harmony:
scale=iw:1/PHI*iw
scale=ih*PHI:ih
· Increase the height, and set the width to 3/2 of the height:
scale=w=3/2*oh:h=3/5*ih
· Increase the size, but make the size a multiple of the chroma
subsample values:
scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
· Increase the width to a maximum of 500 pixels, keep the same input
aspect ratio:
scale=w='min(500\, iw*3/2):h=-1'
separatefields
The "separatefields" takes a frame-based video input and splits each
frame into its components fields, producing a new half height clip with
twice the frame rate and twice the frame count.
This filter use field-dominance information in frame to decide which of
each pair of fields to place first in the output. If it gets it wrong
use setfield filter before "separatefields" filter.
setdar, setsar
The "setdar" filter sets the Display Aspect Ratio for the filter output
video.
This is done by changing the specified Sample (aka Pixel) Aspect Ratio,
according to the following equation:
<DAR> = <HORIZONTAL_RESOLUTION> / <VERTICAL_RESOLUTION> * <SAR>
Keep in mind that the "setdar" filter does not modify the pixel
dimensions of the video frame. Also the display aspect ratio set by
this filter may be changed by later filters in the filterchain, e.g. in
case of scaling or if another "setdar" or a "setsar" filter is applied.
The "setsar" filter sets the Sample (aka Pixel) Aspect Ratio for the
filter output video.
Note that as a consequence of the application of this filter, the
output display aspect ratio will change according to the equation
above.
Keep in mind that the sample aspect ratio set by the "setsar" filter
may be changed by later filters in the filterchain, e.g. if another
"setsar" or a "setdar" filter is applied.
The filters accept the following options:
r, ratio, dar ("setdar" only), sar ("setsar" only)
Set the aspect ratio used by the filter.
The parameter can be a floating point number string, an expression,
or a string of the form num:den, where num and den are the
numerator and denominator of the aspect ratio. If the parameter is
not specified, it is assumed the value "0". In case the form
"num:den" is used, the ":" character should be escaped.
max Set the maximum integer value to use for expressing numerator and
denominator when reducing the expressed aspect ratio to a rational.
Default value is 100.
The parameter sar is an expression containing the following constants:
E, PI, PHI
the corresponding mathematical approximated values for e (euler
number), pi (greek PI), phi (golden ratio)
w, h
the input width and height
a same as w / h
sar input sample aspect ratio
dar input display aspect ratio, it is the same as (w / h) * sar
hsub, vsub
horizontal and vertical chroma subsample values. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
Examples
· To change the display aspect ratio to 16:9, specify one of the
following:
setdar=dar=1.77777
setdar=dar=16/9
setdar=dar=1.77777
· To change the sample aspect ratio to 10:11, specify:
setsar=sar=10/11
· To set a display aspect ratio of 16:9, and specify a maximum
integer value of 1000 in the aspect ratio reduction, use the
command:
setdar=ratio=16/9:max=1000
setfield
Force field for the output video frame.
The "setfield" filter marks the interlace type field for the output
frames. It does not change the input frame, but only sets the
corresponding property, which affects how the frame is treated by
following filters (e.g. "fieldorder" or "yadif").
The filter accepts the following options:
mode
Available values are:
auto
Keep the same field property.
bff Mark the frame as bottom-field-first.
tff Mark the frame as top-field-first.
prog
Mark the frame as progressive.
showinfo
Show a line containing various information for each input video frame.
The input video is not modified.
The shown line contains a sequence of key/value pairs of the form
key:value.
A description of each shown parameter follows:
n sequential number of the input frame, starting from 0
pts Presentation TimeStamp of the input frame, expressed as a number of
time base units. The time base unit depends on the filter input
pad.
pts_time
Presentation TimeStamp of the input frame, expressed as a number of
seconds
pos position of the frame in the input stream, -1 if this information
in unavailable and/or meaningless (for example in case of synthetic
video)
fmt pixel format name
sar sample aspect ratio of the input frame, expressed in the form
num/den
s size of the input frame. For the syntax of this option, check the
"Video size" section in the ffmpeg-utils manual.
i interlaced mode ("P" for "progressive", "T" for top field first,
"B" for bottom field first)
iskey
1 if the frame is a key frame, 0 otherwise
type
picture type of the input frame ("I" for an I-frame, "P" for a
P-frame, "B" for a B-frame, "?" for unknown type). Check also the
documentation of the "AVPictureType" enum and of the
"av_get_picture_type_char" function defined in libavutil/avutil.h.
checksum
Adler-32 checksum (printed in hexadecimal) of all the planes of the
input frame
plane_checksum
Adler-32 checksum (printed in hexadecimal) of each plane of the
input frame, expressed in the form "[c0 c1 c2 c3]"
smartblur
Blur the input video without impacting the outlines.
The filter accepts the following options:
luma_radius, lr
Set the luma radius. The option value must be a float number in the
range [0.1,5.0] that specifies the variance of the gaussian filter
used to blur the image (slower if larger). Default value is 1.0.
luma_strength, ls
Set the luma strength. The option value must be a float number in
the range [-1.0,1.0] that configures the blurring. A value included
in [0.0,1.0] will blur the image whereas a value included in
[-1.0,0.0] will sharpen the image. Default value is 1.0.
luma_threshold, lt
Set the luma threshold used as a coefficient to determine whether a
pixel should be blurred or not. The option value must be an integer
in the range [-30,30]. A value of 0 will filter all the image, a
value included in [0,30] will filter flat areas and a value
included in [-30,0] will filter edges. Default value is 0.
chroma_radius, cr
Set the chroma radius. The option value must be a float number in
the range [0.1,5.0] that specifies the variance of the gaussian
filter used to blur the image (slower if larger). Default value is
1.0.
chroma_strength, cs
Set the chroma strength. The option value must be a float number in
the range [-1.0,1.0] that configures the blurring. A value included
in [0.0,1.0] will blur the image whereas a value included in
[-1.0,0.0] will sharpen the image. Default value is 1.0.
chroma_threshold, ct
Set the chroma threshold used as a coefficient to determine whether
a pixel should be blurred or not. The option value must be an
integer in the range [-30,30]. A value of 0 will filter all the
image, a value included in [0,30] will filter flat areas and a
value included in [-30,0] will filter edges. Default value is 0.
If a chroma option is not explicitly set, the corresponding luma value
is set.
stereo3d
Convert between different stereoscopic image formats.
The filters accept the following options:
in Set stereoscopic image format of input.
Available values for input image formats are:
sbsl
side by side parallel (left eye left, right eye right)
sbsr
side by side crosseye (right eye left, left eye right)
sbs2l
side by side parallel with half width resolution (left eye
left, right eye right)
sbs2r
side by side crosseye with half width resolution (right eye
left, left eye right)
abl above-below (left eye above, right eye below)
abr above-below (right eye above, left eye below)
ab2l
above-below with half height resolution (left eye above, right
eye below)
ab2r
above-below with half height resolution (right eye above, left
eye below)
al alternating frames (left eye first, right eye second)
ar alternating frames (right eye first, left eye second)
Default value is sbsl.
out Set stereoscopic image format of output.
Available values for output image formats are all the input formats
as well as:
arbg
anaglyph red/blue gray (red filter on left eye, blue filter on
right eye)
argg
anaglyph red/green gray (red filter on left eye, green filter
on right eye)
arcg
anaglyph red/cyan gray (red filter on left eye, cyan filter on
right eye)
arch
anaglyph red/cyan half colored (red filter on left eye, cyan
filter on right eye)
arcc
anaglyph red/cyan color (red filter on left eye, cyan filter on
right eye)
arcd
anaglyph red/cyan color optimized with the least squares
projection of dubois (red filter on left eye, cyan filter on
right eye)
agmg
anaglyph green/magenta gray (green filter on left eye, magenta
filter on right eye)
agmh
anaglyph green/magenta half colored (green filter on left eye,
magenta filter on right eye)
agmc
anaglyph green/magenta colored (green filter on left eye,
magenta filter on right eye)
agmd
anaglyph green/magenta color optimized with the least squares
projection of dubois (green filter on left eye, magenta filter
on right eye)
aybg
anaglyph yellow/blue gray (yellow filter on left eye, blue
filter on right eye)
aybh
anaglyph yellow/blue half colored (yellow filter on left eye,
blue filter on right eye)
aybc
anaglyph yellow/blue colored (yellow filter on left eye, blue
filter on right eye)
aybd
anaglyph yellow/blue color optimized with the least squares
projection of dubois (yellow filter on left eye, blue filter on
right eye)
irl interleaved rows (left eye has top row, right eye starts on
next row)
irr interleaved rows (right eye has top row, left eye starts on
next row)
ml mono output (left eye only)
mr mono output (right eye only)
Default value is arcd.
Examples
· Convert input video from side by side parallel to anaglyph
yellow/blue dubois:
stereo3d=sbsl:aybd
· Convert input video from above bellow (left eye above, right eye
below) to side by side crosseye.
stereo3d=abl:sbsr
spp
Apply a simple postprocessing filter that compresses and decompresses
the image at several (or - in the case of quality level 6 - all) shifts
and average the results.
The filter accepts the following options:
quality
Set quality. This option defines the number of levels for
averaging. It accepts an integer in the range 0-6. If set to 0, the
filter will have no effect. A value of 6 means the higher quality.
For each increment of that value the speed drops by a factor of
approximately 2. Default value is 3.
qp Force a constant quantization parameter. If not set, the filter
will use the QP from the video stream (if available).
mode
Set thresholding mode. Available modes are:
hard
Set hard thresholding (default).
soft
Set soft thresholding (better de-ringing effect, but likely
blurrier).
use_bframe_qp
Enable the use of the QP from the B-Frames if set to 1. Using this
option may cause flicker since the B-Frames have often larger QP.
Default is 0 (not enabled).
subtitles
Draw subtitles on top of input video using the libass library.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libass". This filter also requires a build with libavcodec
and libavformat to convert the passed subtitles file to ASS (Advanced
Substation Alpha) subtitles format.
The filter accepts the following options:
filename, f
Set the filename of the subtitle file to read. It must be
specified.
original_size
Specify the size of the original video, the video for which the ASS
file was composed. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Due to a misdesign in ASS
aspect ratio arithmetic, this is necessary to correctly scale the
fonts if the aspect ratio has been changed.
charenc
Set subtitles input character encoding. "subtitles" filter only.
Only useful if not UTF-8.
If the first key is not specified, it is assumed that the first value
specifies the filename.
For example, to render the file sub.srt on top of the input video, use
the command:
subtitles=sub.srt
which is equivalent to:
subtitles=filename=sub.srt
super2xsai
Scale the input by 2x and smooth using the Super2xSaI (Scale and
Interpolate) pixel art scaling algorithm.
Useful for enlarging pixel art images without reducing sharpness.
swapuv
Swap U & V plane.
telecine
Apply telecine process to the video.
This filter accepts the following options:
first_field
top, t
top field first
bottom, b
bottom field first The default value is "top".
pattern
A string of numbers representing the pulldown pattern you wish to
apply. The default value is 23.
Some typical patterns:
NTSC output (30i):
27.5p: 32222
24p: 23 (classic)
24p: 2332 (preferred)
20p: 33
18p: 334
16p: 3444
PAL output (25i):
27.5p: 12222
24p: 222222222223 ("Euro pulldown")
16.67p: 33
16p: 33333334
thumbnail
Select the most representative frame in a given sequence of consecutive
frames.
The filter accepts the following options:
n Set the frames batch size to analyze; in a set of n frames, the
filter will pick one of them, and then handle the next batch of n
frames until the end. Default is 100.
Since the filter keeps track of the whole frames sequence, a bigger n
value will result in a higher memory usage, so a high value is not
recommended.
Examples
· Extract one picture each 50 frames:
thumbnail=50
· Complete example of a thumbnail creation with ffmpeg:
ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
tile
Tile several successive frames together.
The filter accepts the following options:
layout
Set the grid size (i.e. the number of lines and columns). For the
syntax of this option, check the "Video size" section in the
ffmpeg-utils manual.
nb_frames
Set the maximum number of frames to render in the given area. It
must be less than or equal to wxh. The default value is 0, meaning
all the area will be used.
margin
Set the outer border margin in pixels.
padding
Set the inner border thickness (i.e. the number of pixels between
frames). For more advanced padding options (such as having
different values for the edges), refer to the pad video filter.
color
Specify the color of the unused areaFor the syntax of this option,
check the "Color" section in the ffmpeg-utils manual. The default
value of color is "black".
Examples
· Produce 8x8 PNG tiles of all keyframes (-skip_frame nokey) in a
movie:
ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
The -vsync 0 is necessary to prevent ffmpeg from duplicating each
output frame to accommodate the originally detected frame rate.
· Display 5 pictures in an area of "3x2" frames, with 7 pixels
between them, and 2 pixels of initial margin, using mixed flat and
named options:
tile=3x2:nb_frames=5:padding=7:margin=2
tinterlace
Perform various types of temporal field interlacing.
Frames are counted starting from 1, so the first input frame is
considered odd.
The filter accepts the following options:
mode
Specify the mode of the interlacing. This option can also be
specified as a value alone. See below for a list of values for this
option.
Available values are:
merge, 0
Move odd frames into the upper field, even into the lower
field, generating a double height frame at half frame rate.
drop_odd, 1
Only output even frames, odd frames are dropped, generating a
frame with unchanged height at half frame rate.
drop_even, 2
Only output odd frames, even frames are dropped, generating a
frame with unchanged height at half frame rate.
pad, 3
Expand each frame to full height, but pad alternate lines with
black, generating a frame with double height at the same input
frame rate.
interleave_top, 4
Interleave the upper field from odd frames with the lower field
from even frames, generating a frame with unchanged height at
half frame rate.
interleave_bottom, 5
Interleave the lower field from odd frames with the upper field
from even frames, generating a frame with unchanged height at
half frame rate.
interlacex2, 6
Double frame rate with unchanged height. Frames are inserted
each containing the second temporal field from the previous
input frame and the first temporal field from the next input
frame. This mode relies on the top_field_first flag. Useful for
interlaced video displays with no field synchronisation.
Numeric values are deprecated but are accepted for backward
compatibility reasons.
Default mode is "merge".
flags
Specify flags influencing the filter process.
Available value for flags is:
low_pass_filter, vlfp
Enable vertical low-pass filtering in the filter. Vertical
low-pass filtering is required when creating an interlaced
destination from a progressive source which contains high-
frequency vertical detail. Filtering will reduce interlace
'twitter' and Moire patterning.
Vertical low-pass filtering can only be enabled for mode
interleave_top and interleave_bottom.
transpose
Transpose rows with columns in the input video and optionally flip it.
This filter accepts the following options:
dir Specify the transposition direction.
Can assume the following values:
0, 4, cclock_flip
Rotate by 90 degrees counterclockwise and vertically flip
(default), that is:
L.R L.l
. . -> . .
l.r R.r
1, 5, clock
Rotate by 90 degrees clockwise, that is:
L.R l.L
. . -> . .
l.r r.R
2, 6, cclock
Rotate by 90 degrees counterclockwise, that is:
L.R R.r
. . -> . .
l.r L.l
3, 7, clock_flip
Rotate by 90 degrees clockwise and vertically flip, that is:
L.R r.R
. . -> . .
l.r l.L
For values between 4-7, the transposition is only done if the input
video geometry is portrait and not landscape. These values are
deprecated, the "passthrough" option should be used instead.
Numerical values are deprecated, and should be dropped in favor of
symbolic constants.
passthrough
Do not apply the transposition if the input geometry matches the
one specified by the specified value. It accepts the following
values:
none
Always apply transposition.
portrait
Preserve portrait geometry (when height >= width).
landscape
Preserve landscape geometry (when width >= height).
Default value is "none".
For example to rotate by 90 degrees clockwise and preserve portrait
layout:
transpose=dir=1:passthrough=portrait
The command above can also be specified as:
transpose=1:portrait
trim
Trim the input so that the output contains one continuous subpart of
the input.
This filter accepts the following options:
start
Specify time of the start of the kept section, i.e. the frame with
the timestamp start will be the first frame in the output.
end Specify time of the first frame that will be dropped, i.e. the
frame immediately preceding the one with the timestamp end will be
the last frame in the output.
start_pts
Same as start, except this option sets the start timestamp in
timebase units instead of seconds.
end_pts
Same as end, except this option sets the end timestamp in timebase
units instead of seconds.
duration
Specify maximum duration of the output.
start_frame
Number of the first frame that should be passed to output.
end_frame
Number of the first frame that should be dropped.
start, end, duration are expressed as time duration specifications,
check the "Time duration" section in the ffmpeg-utils manual.
Note that the first two sets of the start/end options and the duration
option look at the frame timestamp, while the _frame variants simply
count the frames that pass through the filter. Also note that this
filter does not modify the timestamps. If you wish that the output
timestamps start at zero, insert a setpts filter after the trim filter.
If multiple start or end options are set, this filter tries to be
greedy and keep all the frames that match at least one of the specified
constraints. To keep only the part that matches all the constraints at
once, chain multiple trim filters.
The defaults are such that all the input is kept. So it is possible to
set e.g. just the end values to keep everything before the specified
time.
Examples:
· drop everything except the second minute of input
ffmpeg -i INPUT -vf trim=60:120
· keep only the first second
ffmpeg -i INPUT -vf trim=duration=1
unsharp
Sharpen or blur the input video.
It accepts the following parameters:
luma_msize_x, lx
Set the luma matrix horizontal size. It must be an odd integer
between 3 and 63, default value is 5.
luma_msize_y, ly
Set the luma matrix vertical size. It must be an odd integer
between 3 and 63, default value is 5.
luma_amount, la
Set the luma effect strength. It can be a float number, reasonable
values lay between -1.5 and 1.5.
Negative values will blur the input video, while positive values
will sharpen it, a value of zero will disable the effect.
Default value is 1.0.
chroma_msize_x, cx
Set the chroma matrix horizontal size. It must be an odd integer
between 3 and 63, default value is 5.
chroma_msize_y, cy
Set the chroma matrix vertical size. It must be an odd integer
between 3 and 63, default value is 5.
chroma_amount, ca
Set the chroma effect strength. It can be a float number,
reasonable values lay between -1.5 and 1.5.
Negative values will blur the input video, while positive values
will sharpen it, a value of zero will disable the effect.
Default value is 0.0.
opencl
If set to 1, specify using OpenCL capabilities, only available if
FFmpeg was configured with "--enable-opencl". Default value is 0.
All parameters are optional and default to the equivalent of the string
'5:5:1.0:5:5:0.0'.
Examples
· Apply strong luma sharpen effect:
unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
· Apply strong blur of both luma and chroma parameters:
unsharp=7:7:-2:7:7:-2
vidstabdetect
Analyze video stabilization/deshaking. Perform pass 1 of 2, see
vidstabtransform for pass 2.
This filter generates a file with relative translation and rotation
transform information about subsequent frames, which is then used by
the vidstabtransform filter.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libvidstab".
This filter accepts the following options:
result
Set the path to the file used to write the transforms information.
Default value is transforms.trf.
shakiness
Set how shaky the video is and how quick the camera is. It accepts
an integer in the range 1-10, a value of 1 means little shakiness,
a value of 10 means strong shakiness. Default value is 5.
accuracy
Set the accuracy of the detection process. It must be a value in
the range 1-15. A value of 1 means low accuracy, a value of 15
means high accuracy. Default value is 15.
stepsize
Set stepsize of the search process. The region around minimum is
scanned with 1 pixel resolution. Default value is 6.
mincontrast
Set minimum contrast. Below this value a local measurement field is
discarded. Must be a floating point value in the range 0-1. Default
value is 0.3.
tripod
Set reference frame number for tripod mode.
If enabled, the motion of the frames is compared to a reference
frame in the filtered stream, identified by the specified number.
The idea is to compensate all movements in a more-or-less static
scene and keep the camera view absolutely still.
If set to 0, it is disabled. The frames are counted starting from
1.
show
Show fields and transforms in the resulting frames. It accepts an
integer in the range 0-2. Default value is 0, which disables any
visualization.
Examples
· Use default values:
vidstabdetect
· Analyze strongly shaky movie and put the results in file
mytransforms.trf:
vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
· Visualize the result of internal transformations in the resulting
video:
vidstabdetect=show=1
· Analyze a video with medium shakiness using ffmpeg:
ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
vidstabtransform
Video stabilization/deshaking: pass 2 of 2, see vidstabdetect for pass
1.
Read a file with transform information for each frame and
apply/compensate them. Together with the vidstabdetect filter this can
be used to deshake videos. See also
<http://public.hronopik.de/vid.stab>. It is important to also use the
unsharp filter, see below.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libvidstab".
Options
input
Set path to the file used to read the transforms. Default value is
transforms.trf).
smoothing
Set the number of frames (value*2 + 1) used for lowpass filtering
the camera movements. Default value is 10.
For example a number of 10 means that 21 frames are used (10 in the
past and 10 in the future) to smoothen the motion in the video. A
larger values leads to a smoother video, but limits the
acceleration of the camera (pan/tilt movements). 0 is a special
case where a static camera is simulated.
optalgo
Set the camera path optimization algorithm.
Accepted values are:
gauss
gaussian kernel low-pass filter on camera motion (default)
avg averaging on transformations
maxshift
Set maximal number of pixels to translate frames. Default value is
-1, meaning no limit.
maxangle
Set maximal angle in radians (degree*PI/180) to rotate frames.
Default value is -1, meaning no limit.
crop
Specify how to deal with borders that may be visible due to
movement compensation.
Available values are:
keep
keep image information from previous frame (default)
black
fill the border black
invert
Invert transforms if set to 1. Default value is 0.
relative
Consider transforms as relative to previsou frame if set to 1,
absolute if set to 0. Default value is 0.
zoom
Set percentage to zoom. A positive value will result in a zoom-in
effect, a negative value in a zoom-out effect. Default value is 0
(no zoom).
optzoom
Set optimal zooming to avoid borders.
Accepted values are:
0 disabled
1 optimal static zoom value is determined (only very strong
movements will lead to visible borders) (default)
2 optimal adaptive zoom value is determined (no borders will be
visible), see zoomspeed
Note that the value given at zoom is added to the one calculated
here.
zoomspeed
Set percent to zoom maximally each frame (enabled when optzoom is
set to 2). Range is from 0 to 5, default value is 0.25.
interpol
Specify type of interpolation.
Available values are:
no no interpolation
linear
linear only horizontal
bilinear
linear in both directions (default)
bicubic
cubic in both directions (slow)
tripod
Enable virtual tripod mode if set to 1, which is equivalent to
"relative=0:smoothing=0". Default value is 0.
Use also "tripod" option of vidstabdetect.
debug
Increase log verbosity if set to 1. Also the detected global
motions are written to the temporary file global_motions.trf.
Default value is 0.
Examples
· Use ffmpeg for a typical stabilization with default values:
ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
Note the use of the unsharp filter which is always recommended.
· Zoom in a bit more and load transform data from a given file:
vidstabtransform=zoom=5:input="mytransforms.trf"
· Smoothen the video even more:
vidstabtransform=smoothing=30
vflip
Flip the input video vertically.
For example, to vertically flip a video with ffmpeg:
ffmpeg -i in.avi -vf "vflip" out.avi
vignette
Make or reverse a natural vignetting effect.
The filter accepts the following options:
angle, a
Set lens angle expression as a number of radians.
The value is clipped in the "[0,PI/2]" range.
Default value: "PI/5"
x0
y0 Set center coordinates expressions. Respectively "w/2" and "h/2" by
default.
mode
Set forward/backward mode.
Available modes are:
forward
The larger the distance from the central point, the darker the
image becomes.
backward
The larger the distance from the central point, the brighter
the image becomes. This can be used to reverse a vignette
effect, though there is no automatic detection to extract the
lens angle and other settings (yet). It can also be used to
create a burning effect.
Default value is forward.
eval
Set evaluation mode for the expressions (angle, x0, y0).
It accepts the following values:
init
Evaluate expressions only once during the filter
initialization.
frame
Evaluate expressions for each incoming frame. This is way
slower than the init mode since it requires all the scalers to
be re-computed, but it allows advanced dynamic expressions.
Default value is init.
dither
Set dithering to reduce the circular banding effects. Default is 1
(enabled).
aspect
Set vignette aspect. This setting allows one to adjust the shape of
the vignette. Setting this value to the SAR of the input will make
a rectangular vignetting following the dimensions of the video.
Default is "1/1".
Expressions
The alpha, x0 and y0 expressions can contain the following parameters.
w
h input width and height
n the number of input frame, starting from 0
pts the PTS (Presentation TimeStamp) time of the filtered video frame,
expressed in TB units, NAN if undefined
r frame rate of the input video, NAN if the input frame rate is
unknown
t the PTS (Presentation TimeStamp) of the filtered video frame,
expressed in seconds, NAN if undefined
tb time base of the input video
Examples
· Apply simple strong vignetting effect:
vignette=PI/4
· Make a flickering vignetting:
vignette='PI/4+random(1)*PI/50':eval=frame
w3fdif
Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
Deinterlacing Filter").
Based on the process described by Martin Weston for BBC R&D, and
implemented based on the de-interlace algorithm written by Jim
Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter uses
filter coefficients calculated by BBC R&D.
There are two sets of filter coefficients, so called "simple": and
"complex". Which set of filter coefficients is used can be set by
passing an optional parameter:
filter
Set the interlacing filter coefficients. Accepts one of the
following values:
simple
Simple filter coefficient set.
complex
More-complex filter coefficient set.
Default value is complex.
deint
Specify which frames to deinterlace. Accept one of the following
values:
all Deinterlace all frames,
interlaced
Only deinterlace frames marked as interlaced.
Default value is all.
yadif
Deinterlace the input video ("yadif" means "yet another deinterlacing
filter").
This filter accepts the following options:
mode
The interlacing mode to adopt, accepts one of the following values:
0, send_frame
output 1 frame for each frame
1, send_field
output 1 frame for each field
2, send_frame_nospatial
like "send_frame" but skip spatial interlacing check
3, send_field_nospatial
like "send_field" but skip spatial interlacing check
Default value is "send_frame".
parity
The picture field parity assumed for the input interlaced video,
accepts one of the following values:
0, tff
assume top field first
1, bff
assume bottom field first
-1, auto
enable automatic detection
Default value is "auto". If interlacing is unknown or decoder does
not export this information, top field first will be assumed.
deint
Specify which frames to deinterlace. Accept one of the following
values:
0, all
deinterlace all frames
1, interlaced
only deinterlace frames marked as interlaced
Default value is "all".
VIDEO SOURCES
Below is a description of the currently available video sources.
buffer
Buffer video frames, and make them available to the filter chain.
This source is mainly intended for a programmatic use, in particular
through the interface defined in libavfilter/vsrc_buffer.h.
This source accepts the following options:
video_size
Specify the size (width and height) of the buffered video frames.
For the syntax of this option, check the "Video size" section in
the ffmpeg-utils manual.
width
Input video width.
height
Input video height.
pix_fmt
A string representing the pixel format of the buffered video
frames. It may be a number corresponding to a pixel format, or a
pixel format name.
time_base
Specify the timebase assumed by the timestamps of the buffered
frames.
frame_rate
Specify the frame rate expected for the video stream.
pixel_aspect, sar
Specify the sample aspect ratio assumed by the video frames.
sws_param
Specify the optional parameters to be used for the scale filter
which is automatically inserted when an input change is detected in
the input size or format.
For example:
buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
will instruct the source to accept video frames with size 320x240 and
with format "yuv410p", assuming 1/24 as the timestamps timebase and
square pixels (1:1 sample aspect ratio). Since the pixel format with
name "yuv410p" corresponds to the number 6 (check the enum
AVPixelFormat definition in libavutil/pixfmt.h), this example
corresponds to:
buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
Alternatively, the options can be specified as a flat string, but this
syntax is deprecated:
width:height:pix_fmt:time_base.num:time_base.den:pixel_aspect.num:pixel_aspect.den[:sws_param]
cellauto
Create a pattern generated by an elementary cellular automaton.
The initial state of the cellular automaton can be defined through the
filename, and pattern options. If such options are not specified an
initial state is created randomly.
At each new frame a new row in the video is filled with the result of
the cellular automaton next generation. The behavior when the whole
frame is filled is defined by the scroll option.
This source accepts the following options:
filename, f
Read the initial cellular automaton state, i.e. the starting row,
from the specified file. In the file, each non-whitespace
character is considered an alive cell, a newline will terminate the
row, and further characters in the file will be ignored.
pattern, p
Read the initial cellular automaton state, i.e. the starting row,
from the specified string.
Each non-whitespace character in the string is considered an alive
cell, a newline will terminate the row, and further characters in
the string will be ignored.
rate, r
Set the video rate, that is the number of frames generated per
second. Default is 25.
random_fill_ratio, ratio
Set the random fill ratio for the initial cellular automaton row.
It is a floating point number value ranging from 0 to 1, defaults
to 1/PHI.
This option is ignored when a file or a pattern is specified.
random_seed, seed
Set the seed for filling randomly the initial row, must be an
integer included between 0 and UINT32_MAX. If not specified, or if
explicitly set to -1, the filter will try to use a good random seed
on a best effort basis.
rule
Set the cellular automaton rule, it is a number ranging from 0 to
255. Default value is 110.
size, s
Set the size of the output video. For the syntax of this option,
check the "Video size" section in the ffmpeg-utils manual.
If filename or pattern is specified, the size is set by default to
the width of the specified initial state row, and the height is set
to width * PHI.
If size is set, it must contain the width of the specified pattern
string, and the specified pattern will be centered in the larger
row.
If a filename or a pattern string is not specified, the size value
defaults to "320x518" (used for a randomly generated initial
state).
scroll
If set to 1, scroll the output upward when all the rows in the
output have been already filled. If set to 0, the new generated row
will be written over the top row just after the bottom row is
filled. Defaults to 1.
start_full, full
If set to 1, completely fill the output with generated rows before
outputting the first frame. This is the default behavior, for
disabling set the value to 0.
stitch
If set to 1, stitch the left and right row edges together. This is
the default behavior, for disabling set the value to 0.
Examples
· Read the initial state from pattern, and specify an output of size
200x400.
cellauto=f=pattern:s=200x400
· Generate a random initial row with a width of 200 cells, with a
fill ratio of 2/3:
cellauto=ratio=2/3:s=200x200
· Create a pattern generated by rule 18 starting by a single alive
cell centered on an initial row with width 100:
cellauto=p=@s=100x400:full=0:rule=18
· Specify a more elaborated initial pattern:
cellauto=p='@@ @ @@':s=100x400:full=0:rule=18
mandelbrot
Generate a Mandelbrot set fractal, and progressively zoom towards the
point specified with start_x and start_y.
This source accepts the following options:
end_pts
Set the terminal pts value. Default value is 400.
end_scale
Set the terminal scale value. Must be a floating point value.
Default value is 0.3.
inner
Set the inner coloring mode, that is the algorithm used to draw the
Mandelbrot fractal internal region.
It shall assume one of the following values:
black
Set black mode.
convergence
Show time until convergence.
mincol
Set color based on point closest to the origin of the
iterations.
period
Set period mode.
Default value is mincol.
bailout
Set the bailout value. Default value is 10.0.
maxiter
Set the maximum of iterations performed by the rendering algorithm.
Default value is 7189.
outer
Set outer coloring mode. It shall assume one of following values:
iteration_count
Set iteration cound mode.
normalized_iteration_count
set normalized iteration count mode.
Default value is normalized_iteration_count.
rate, r
Set frame rate, expressed as number of frames per second. Default
value is "25".
size, s
Set frame size. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is
"640x480".
start_scale
Set the initial scale value. Default value is 3.0.
start_x
Set the initial x position. Must be a floating point value between
-100 and 100. Default value is
-0.743643887037158704752191506114774.
start_y
Set the initial y position. Must be a floating point value between
-100 and 100. Default value is
-0.131825904205311970493132056385139.
mptestsrc
Generate various test patterns, as generated by the MPlayer test
filter.
The size of the generated video is fixed, and is 256x256. This source
is useful in particular for testing encoding features.
This source accepts the following options:
rate, r
Specify the frame rate of the sourced video, as the number of
frames generated per second. It has to be a string in the format
frame_rate_num/frame_rate_den, an integer number, a float number or
a valid video frame rate abbreviation. The default value is "25".
duration, d
Set the video duration of the sourced video. The accepted syntax
is:
[-]HH:MM:SS[.m...]
[-]S+[.m...]
See also the function "av_parse_time()".
If not specified, or the expressed duration is negative, the video
is supposed to be generated forever.
test, t
Set the number or the name of the test to perform. Supported tests
are:
dc_luma
dc_chroma
freq_luma
freq_chroma
amp_luma
amp_chroma
cbp
mv
ring1
ring2
all
Default value is "all", which will cycle through the list of all
tests.
For example the following:
testsrc=t=dc_luma
will generate a "dc_luma" test pattern.
frei0r_src
Provide a frei0r source.
To enable compilation of this filter you need to install the frei0r
header and configure FFmpeg with "--enable-frei0r".
This source accepts the following options:
size
The size of the video to generate. For the syntax of this option,
check the "Video size" section in the ffmpeg-utils manual.
framerate
Framerate of the generated video, may be a string of the form
num/den or a frame rate abbreviation.
filter_name
The name to the frei0r source to load. For more information
regarding frei0r and how to set the parameters read the section
frei0r in the description of the video filters.
filter_params
A '|'-separated list of parameters to pass to the frei0r source.
For example, to generate a frei0r partik0l source with size 200x200 and
frame rate 10 which is overlayed on the overlay filter main input:
frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
life
Generate a life pattern.
This source is based on a generalization of John Conway's life game.
The sourced input represents a life grid, each pixel represents a cell
which can be in one of two possible states, alive or dead. Every cell
interacts with its eight neighbours, which are the cells that are
horizontally, vertically, or diagonally adjacent.
At each interaction the grid evolves according to the adopted rule,
which specifies the number of neighbor alive cells which will make a
cell stay alive or born. The rule option allows one to specify the rule
to adopt.
This source accepts the following options:
filename, f
Set the file from which to read the initial grid state. In the
file, each non-whitespace character is considered an alive cell,
and newline is used to delimit the end of each row.
If this option is not specified, the initial grid is generated
randomly.
rate, r
Set the video rate, that is the number of frames generated per
second. Default is 25.
random_fill_ratio, ratio
Set the random fill ratio for the initial random grid. It is a
floating point number value ranging from 0 to 1, defaults to 1/PHI.
It is ignored when a file is specified.
random_seed, seed
Set the seed for filling the initial random grid, must be an
integer included between 0 and UINT32_MAX. If not specified, or if
explicitly set to -1, the filter will try to use a good random seed
on a best effort basis.
rule
Set the life rule.
A rule can be specified with a code of the kind "SNS/BNB", where NS
and NB are sequences of numbers in the range 0-8, NS specifies the
number of alive neighbor cells which make a live cell stay alive,
and NB the number of alive neighbor cells which make a dead cell to
become alive (i.e. to "born"). "s" and "b" can be used in place of
"S" and "B", respectively.
Alternatively a rule can be specified by an 18-bits integer. The 9
high order bits are used to encode the next cell state if it is
alive for each number of neighbor alive cells, the low order bits
specify the rule for "borning" new cells. Higher order bits encode
for an higher number of neighbor cells. For example the number
6153 = "(12<<9)+9" specifies a stay alive rule of 12 and a born
rule of 9, which corresponds to "S23/B03".
Default value is "S23/B3", which is the original Conway's game of
life rule, and will keep a cell alive if it has 2 or 3 neighbor
alive cells, and will born a new cell if there are three alive
cells around a dead cell.
size, s
Set the size of the output video. For the syntax of this option,
check the "Video size" section in the ffmpeg-utils manual.
If filename is specified, the size is set by default to the same
size of the input file. If size is set, it must contain the size
specified in the input file, and the initial grid defined in that
file is centered in the larger resulting area.
If a filename is not specified, the size value defaults to
"320x240" (used for a randomly generated initial grid).
stitch
If set to 1, stitch the left and right grid edges together, and the
top and bottom edges also. Defaults to 1.
mold
Set cell mold speed. If set, a dead cell will go from death_color
to mold_color with a step of mold. mold can have a value from 0 to
255.
life_color
Set the color of living (or new born) cells.
death_color
Set the color of dead cells. If mold is set, this is the first
color used to represent a dead cell.
mold_color
Set mold color, for definitely dead and moldy cells.
For the syntax of these 3 color options, check the "Color" section
in the ffmpeg-utils manual.
Examples
· Read a grid from pattern, and center it on a grid of size 300x300
pixels:
life=f=pattern:s=300x300
· Generate a random grid of size 200x200, with a fill ratio of 2/3:
life=ratio=2/3:s=200x200
· Specify a custom rule for evolving a randomly generated grid:
life=rule=S14/B34
· Full example with slow death effect (mold) using ffplay:
ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
The "color" source provides an uniformly colored input.
The "haldclutsrc" source provides an identity Hald CLUT. See also
haldclut filter.
The "nullsrc" source returns unprocessed video frames. It is mainly
useful to be employed in analysis / debugging tools, or as the source
for filters which ignore the input data.
The "rgbtestsrc" source generates an RGB test pattern useful for
detecting RGB vs BGR issues. You should see a red, green and blue
stripe from top to bottom.
The "smptebars" source generates a color bars pattern, based on the
SMPTE Engineering Guideline EG 1-1990.
The "smptehdbars" source generates a color bars pattern, based on the
SMPTE RP 219-2002.
The "testsrc" source generates a test video pattern, showing a color
pattern, a scrolling gradient and a timestamp. This is mainly intended
for testing purposes.
The sources accept the following options:
color, c
Specify the color of the source, only available in the "color"
source. For the syntax of this option, check the "Color" section in
the ffmpeg-utils manual.
level
Specify the level of the Hald CLUT, only available in the
"haldclutsrc" source. A level of "N" generates a picture of "N*N*N"
by "N*N*N" pixels to be used as identity matrix for 3D lookup
tables. Each component is coded on a "1/(N*N)" scale.
size, s
Specify the size of the sourced video. For the syntax of this
option, check the "Video size" section in the ffmpeg-utils manual.
The default value is "320x240".
This option is not available with the "haldclutsrc" filter.
rate, r
Specify the frame rate of the sourced video, as the number of
frames generated per second. It has to be a string in the format
frame_rate_num/frame_rate_den, an integer number, a float number or
a valid video frame rate abbreviation. The default value is "25".
sar Set the sample aspect ratio of the sourced video.
duration, d
Set the video duration of the sourced video. The accepted syntax
is:
[-]HH[:MM[:SS[.m...]]]
[-]S+[.m...]
See also the function "av_parse_time()".
If not specified, or the expressed duration is negative, the video
is supposed to be generated forever.
decimals, n
Set the number of decimals to show in the timestamp, only available
in the "testsrc" source.
The displayed timestamp value will correspond to the original
timestamp value multiplied by the power of 10 of the specified
value. Default value is 0.
For example the following:
testsrc=duration=5.3:size=qcif:rate=10
will generate a video with a duration of 5.3 seconds, with size 176x144
and a frame rate of 10 frames per second.
The following graph description will generate a red source with an
opacity of 0.2, with size "qcif" and a frame rate of 10 frames per
second.
color=c=red@0.2:s=qcif:r=10
If the input content is to be ignored, "nullsrc" can be used. The
following command generates noise in the luminance plane by employing
the "geq" filter:
nullsrc=s=256x256, geq=random(1)*255:128:128
Commands
The "color" source supports the following commands:
c, color
Set the color of the created image. Accepts the same syntax of the
corresponding color option.
VIDEO SINKS
Below is a description of the currently available video sinks.
buffersink
Buffer video frames, and make them available to the end of the filter
graph.
This sink is mainly intended for a programmatic use, in particular
through the interface defined in libavfilter/buffersink.h or the
options system.
It accepts a pointer to an AVBufferSinkContext structure, which defines
the incoming buffers' formats, to be passed as the opaque parameter to
"avfilter_init_filter" for initialization.
nullsink
Null video sink, do absolutely nothing with the input video. It is
mainly useful as a template and to be employed in analysis / debugging
tools.
MULTIMEDIA FILTERS
Below is a description of the currently available multimedia filters.
avectorscope
Convert input audio to a video output, representing the audio vector
scope.
The filter is used to measure the difference between channels of stereo
audio stream. A monoaural signal, consisting of identical left and
right signal, results in straight vertical line. Any stereo separation
is visible as a deviation from this line, creating a Lissajous figure.
If the straight (or deviation from it) but horizontal line appears this
indicates that the left and right channels are out of phase.
The filter accepts the following options:
mode, m
Set the vectorscope mode.
Available values are:
lissajous
Lissajous rotated by 45 degrees.
lissajous_xy
Same as above but not rotated.
Default value is lissajous.
size, s
Set the video size for the output. For the syntax of this option,
check the "Video size" section in the ffmpeg-utils manual. Default
value is "400x400".
rate, r
Set the output frame rate. Default value is 25.
rc
gc
bc Specify the red, green and blue contrast. Default values are 40,
160 and 80. Allowed range is "[0, 255]".
rf
gf
bf Specify the red, green and blue fade. Default values are 15, 10 and
5. Allowed range is "[0, 255]".
zoom
Set the zoom factor. Default value is 1. Allowed range is "[1,
10]".
Examples
· Complete example using ffplay:
ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
[a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
concat
Concatenate audio and video streams, joining them together one after
the other.
The filter works on segments of synchronized video and audio streams.
All segments must have the same number of streams of each type, and
that will also be the number of streams at output.
The filter accepts the following options:
n Set the number of segments. Default is 2.
v Set the number of output video streams, that is also the number of
video streams in each segment. Default is 1.
a Set the number of output audio streams, that is also the number of
video streams in each segment. Default is 0.
unsafe
Activate unsafe mode: do not fail if segments have a different
format.
The filter has v+a outputs: first v video outputs, then a audio
outputs.
There are nx(v+a) inputs: first the inputs for the first segment, in
the same order as the outputs, then the inputs for the second segment,
etc.
Related streams do not always have exactly the same duration, for
various reasons including codec frame size or sloppy authoring. For
that reason, related synchronized streams (e.g. a video and its audio
track) should be concatenated at once. The concat filter will use the
duration of the longest stream in each segment (except the last one),
and if necessary pad shorter audio streams with silence.
For this filter to work correctly, all segments must start at timestamp
0.
All corresponding streams must have the same parameters in all
segments; the filtering system will automatically select a common pixel
format for video streams, and a common sample format, sample rate and
channel layout for audio streams, but other settings, such as
resolution, must be converted explicitly by the user.
Different frame rates are acceptable but will result in variable frame
rate at output; be sure to configure the output file to handle it.
Examples
· Concatenate an opening, an episode and an ending, all in bilingual
version (video in stream 0, audio in streams 1 and 2):
ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
'[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
concat=n=3:v=1:a=2 [v] [a1] [a2]' \
-map '[v]' -map '[a1]' -map '[a2]' output.mkv
· Concatenate two parts, handling audio and video separately, using
the (a)movie sources, and adjusting the resolution:
movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
[v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
Note that a desync will happen at the stitch if the audio and video
streams do not have exactly the same duration in the first file.
ebur128
EBU R128 scanner filter. This filter takes an audio stream as input and
outputs it unchanged. By default, it logs a message at a frequency of
10Hz with the Momentary loudness (identified by "M"), Short-term
loudness ("S"), Integrated loudness ("I") and Loudness Range ("LRA").
The filter also has a video output (see the video option) with a real
time graph to observe the loudness evolution. The graphic contains the
logged message mentioned above, so it is not printed anymore when this
option is set, unless the verbose logging is set. The main graphing
area contains the short-term loudness (3 seconds of analysis), and the
gauge on the right is for the momentary loudness (400 milliseconds).
More information about the Loudness Recommendation EBU R128 on
<http://tech.ebu.ch/loudness>.
The filter accepts the following options:
video
Activate the video output. The audio stream is passed unchanged
whether this option is set or no. The video stream will be the
first output stream if activated. Default is 0.
size
Set the video size. This option is for video only. For the syntax
of this option, check the "Video size" section in the ffmpeg-utils
manual. Default and minimum resolution is "640x480".
meter
Set the EBU scale meter. Default is 9. Common values are 9 and 18,
respectively for EBU scale meter +9 and EBU scale meter +18. Any
other integer value between this range is allowed.
metadata
Set metadata injection. If set to 1, the audio input will be
segmented into 100ms output frames, each of them containing various
loudness information in metadata. All the metadata keys are
prefixed with "lavfi.r128.".
Default is 0.
framelog
Force the frame logging level.
Available values are:
info
information logging level
verbose
verbose logging level
By default, the logging level is set to info. If the video or the
metadata options are set, it switches to verbose.
peak
Set peak mode(s).
Available modes can be cumulated (the option is a "flag" type).
Possible values are:
none
Disable any peak mode (default).
sample
Enable sample-peak mode.
Simple peak mode looking for the higher sample value. It logs a
message for sample-peak (identified by "SPK").
true
Enable true-peak mode.
If enabled, the peak lookup is done on an over-sampled version
of the input stream for better peak accuracy. It logs a message
for true-peak. (identified by "TPK") and true-peak per frame
(identified by "FTPK"). This mode requires a build with
"libswresample".
Examples
· Real-time graph using ffplay, with a EBU scale meter +18:
ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
· Run an analysis with ffmpeg:
ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
interleave, ainterleave
Temporally interleave frames from several inputs.
"interleave" works with video inputs, "ainterleave" with audio.
These filters read frames from several inputs and send the oldest
queued frame to the output.
Input streams must have a well defined, monotonically increasing frame
timestamp values.
In order to submit one frame to output, these filters need to enqueue
at least one frame for each input, so they cannot work in case one
input is not yet terminated and will not receive incoming frames.
For example consider the case when one input is a "select" filter which
always drop input frames. The "interleave" filter will keep reading
from that input, but it will never be able to send new frames to output
until the input will send an end-of-stream signal.
Also, depending on inputs synchronization, the filters will drop frames
in case one input receives more frames than the other ones, and the
queue is already filled.
These filters accept the following options:
nb_inputs, n
Set the number of different inputs, it is 2 by default.
Examples
· Interleave frames belonging to different streams using ffmpeg:
ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
· Add flickering blur effect:
select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
perms, aperms
Set read/write permissions for the output frames.
These filters are mainly aimed at developers to test direct path in the
following filter in the filtergraph.
The filters accept the following options:
mode
Select the permissions mode.
It accepts the following values:
none
Do nothing. This is the default.
ro Set all the output frames read-only.
rw Set all the output frames directly writable.
toggle
Make the frame read-only if writable, and writable if read-
only.
random
Set each output frame read-only or writable randomly.
seed
Set the seed for the random mode, must be an integer included
between 0 and "UINT32_MAX". If not specified, or if explicitly set
to "-1", the filter will try to use a good random seed on a best
effort basis.
Note: in case of auto-inserted filter between the permission filter and
the following one, the permission might not be received as expected in
that following filter. Inserting a format or aformat filter before the
perms/aperms filter can avoid this problem.
select, aselect
Select frames to pass in output.
This filter accepts the following options:
expr, e
Set expression, which is evaluated for each input frame.
If the expression is evaluated to zero, the frame is discarded.
If the evaluation result is negative or NaN, the frame is sent to
the first output; otherwise it is sent to the output with index
"ceil(val)-1", assuming that the input index starts from 0.
For example a value of 1.2 corresponds to the output with index
"ceil(1.2)-1 = 2-1 = 1", that is the second output.
outputs, n
Set the number of outputs. The output to which to send the selected
frame is based on the result of the evaluation. Default value is 1.
The expression can contain the following constants:
n the sequential number of the filtered frame, starting from 0
selected_n
the sequential number of the selected frame, starting from 0
prev_selected_n
the sequential number of the last selected frame, NAN if undefined
TB timebase of the input timestamps
pts the PTS (Presentation TimeStamp) of the filtered video frame,
expressed in TB units, NAN if undefined
t the PTS (Presentation TimeStamp) of the filtered video frame,
expressed in seconds, NAN if undefined
prev_pts
the PTS of the previously filtered video frame, NAN if undefined
prev_selected_pts
the PTS of the last previously filtered video frame, NAN if
undefined
prev_selected_t
the PTS of the last previously selected video frame, NAN if
undefined
start_pts
the PTS of the first video frame in the video, NAN if undefined
start_t
the time of the first video frame in the video, NAN if undefined
pict_type (video only)
the type of the filtered frame, can assume one of the following
values:
I
P
B
S
SI
SP
BI
interlace_type (video only)
the frame interlace type, can assume one of the following values:
PROGRESSIVE
the frame is progressive (not interlaced)
TOPFIRST
the frame is top-field-first
BOTTOMFIRST
the frame is bottom-field-first
consumed_sample_n (audio only)
the number of selected samples before the current frame
samples_n (audio only)
the number of samples in the current frame
sample_rate (audio only)
the input sample rate
key 1 if the filtered frame is a key-frame, 0 otherwise
pos the position in the file of the filtered frame, -1 if the
information is not available (e.g. for synthetic video)
scene (video only)
value between 0 and 1 to indicate a new scene; a low value reflects
a low probability for the current frame to introduce a new scene,
while a higher value means the current frame is more likely to be
one (see the example below)
The default value of the select expression is "1".
Examples
· Select all frames in input:
select
The example above is the same as:
select=1
· Skip all frames:
select=0
· Select only I-frames:
select='eq(pict_type\,I)'
· Select one frame every 100:
select='not(mod(n\,100))'
· Select only frames contained in the 10-20 time interval:
select=between(t\,10\,20)
· Select only I frames contained in the 10-20 time interval:
select=between(t\,10\,20)*eq(pict_type\,I)
· Select frames with a minimum distance of 10 seconds:
select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
· Use aselect to select only audio frames with samples number > 100:
aselect='gt(samples_n\,100)'
· Create a mosaic of the first scenes:
ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
Comparing scene against a value between 0.3 and 0.5 is generally a
sane choice.
· Send even and odd frames to separate outputs, and compose them:
select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
sendcmd, asendcmd
Send commands to filters in the filtergraph.
These filters read commands to be sent to other filters in the
filtergraph.
"sendcmd" must be inserted between two video filters, "asendcmd" must
be inserted between two audio filters, but apart from that they act the
same way.
The specification of commands can be provided in the filter arguments
with the commands option, or in a file specified by the filename
option.
These filters accept the following options:
commands, c
Set the commands to be read and sent to the other filters.
filename, f
Set the filename of the commands to be read and sent to the other
filters.
Commands syntax
A commands description consists of a sequence of interval
specifications, comprising a list of commands to be executed when a
particular event related to that interval occurs. The occurring event
is typically the current frame time entering or leaving a given time
interval.
An interval is specified by the following syntax:
<START>[-<END>] <COMMANDS>;
The time interval is specified by the START and END times. END is
optional and defaults to the maximum time.
The current frame time is considered within the specified interval if
it is included in the interval [START, END), that is when the time is
greater or equal to START and is lesser than END.
COMMANDS consists of a sequence of one or more command specifications,
separated by ",", relating to that interval. The syntax of a command
specification is given by:
[<FLAGS>] <TARGET> <COMMAND> <ARG>
FLAGS is optional and specifies the type of events relating to the time
interval which enable sending the specified command, and must be a non-
null sequence of identifier flags separated by "+" or "|" and enclosed
between "[" and "]".
The following flags are recognized:
enter
The command is sent when the current frame timestamp enters the
specified interval. In other words, the command is sent when the
previous frame timestamp was not in the given interval, and the
current is.
leave
The command is sent when the current frame timestamp leaves the
specified interval. In other words, the command is sent when the
previous frame timestamp was in the given interval, and the current
is not.
If FLAGS is not specified, a default value of "[enter]" is assumed.
TARGET specifies the target of the command, usually the name of the
filter class or a specific filter instance name.
COMMAND specifies the name of the command for the target filter.
ARG is optional and specifies the optional list of argument for the
given COMMAND.
Between one interval specification and another, whitespaces, or
sequences of characters starting with "#" until the end of line, are
ignored and can be used to annotate comments.
A simplified BNF description of the commands specification syntax
follows:
<COMMAND_FLAG> ::= "enter" | "leave"
<COMMAND_FLAGS> ::= <COMMAND_FLAG> [(+|"|")<COMMAND_FLAG>]
<COMMAND> ::= ["[" <COMMAND_FLAGS> "]"] <TARGET> <COMMAND> [<ARG>]
<COMMANDS> ::= <COMMAND> [,<COMMANDS>]
<INTERVAL> ::= <START>[-<END>] <COMMANDS>
<INTERVALS> ::= <INTERVAL>[;<INTERVALS>]
Examples
· Specify audio tempo change at second 4:
asendcmd=c='4.0 atempo tempo 1.5',atempo
· Specify a list of drawtext and hue commands in a file.
# show text in the interval 5-10
5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
[leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
# desaturate the image in the interval 15-20
15.0-20.0 [enter] hue s 0,
[enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
[leave] hue s 1,
[leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
# apply an exponential saturation fade-out effect, starting from time 25
25 [enter] hue s exp(25-t)
A filtergraph allowing to read and process the above command list
stored in a file test.cmd, can be specified with:
sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
setpts, asetpts
Change the PTS (presentation timestamp) of the input frames.
"setpts" works on video frames, "asetpts" on audio frames.
This filter accepts the following options:
expr
The expression which is evaluated for each frame to construct its
timestamp.
The expression is evaluated through the eval API and can contain the
following constants:
FRAME_RATE
frame rate, only defined for constant frame-rate video
PTS the presentation timestamp in input
N the count of the input frame for video or the number of consumed
samples, not including the current frame for audio, starting from
0.
NB_CONSUMED_SAMPLES
the number of consumed samples, not including the current frame
(only audio)
NB_SAMPLES, S
the number of samples in the current frame (only audio)
SAMPLE_RATE, SR
audio sample rate
STARTPTS
the PTS of the first frame
STARTT
the time in seconds of the first frame
INTERLACED
tell if the current frame is interlaced
T the time in seconds of the current frame
POS original position in the file of the frame, or undefined if
undefined for the current frame
PREV_INPTS
previous input PTS
PREV_INT
previous input time in seconds
PREV_OUTPTS
previous output PTS
PREV_OUTT
previous output time in seconds
RTCTIME
wallclock (RTC) time in microseconds. This is deprecated, use
time(0) instead.
RTCSTART
wallclock (RTC) time at the start of the movie in microseconds
TB timebase of the input timestamps
Examples
· Start counting PTS from zero
setpts=PTS-STARTPTS
· Apply fast motion effect:
setpts=0.5*PTS
· Apply slow motion effect:
setpts=2.0*PTS
· Set fixed rate of 25 frames per second:
setpts=N/(25*TB)
· Set fixed rate 25 fps with some jitter:
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
· Apply an offset of 10 seconds to the input PTS:
setpts=PTS+10/TB
· Generate timestamps from a "live source" and rebase onto the
current timebase:
setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
· Generate timestamps by counting samples:
asetpts=N/SR/TB
settb, asettb
Set the timebase to use for the output frames timestamps. It is mainly
useful for testing timebase configuration.
This filter accepts the following options:
expr, tb
The expression which is evaluated into the output timebase.
The value for tb is an arithmetic expression representing a rational.
The expression can contain the constants "AVTB" (the default timebase),
"intb" (the input timebase) and "sr" (the sample rate, audio only).
Default value is "intb".
Examples
· Set the timebase to 1/25:
settb=expr=1/25
· Set the timebase to 1/10:
settb=expr=0.1
· Set the timebase to 1001/1000:
settb=1+0.001
· Set the timebase to 2*intb:
settb=2*intb
· Set the default timebase value:
settb=AVTB
showspectrum
Convert input audio to a video output, representing the audio frequency
spectrum.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this
option, check the "Video size" section in the ffmpeg-utils manual.
Default value is "640x512".
slide
Specify if the spectrum should slide along the window. Default
value is 0.
mode
Specify display mode.
It accepts the following values:
combined
all channels are displayed in the same row
separate
all channels are displayed in separate rows
Default value is combined.
color
Specify display color mode.
It accepts the following values:
channel
each channel is displayed in a separate color
intensity
each channel is is displayed using the same color scheme
Default value is channel.
scale
Specify scale used for calculating intensity color values.
It accepts the following values:
lin linear
sqrt
square root, default
cbrt
cubic root
log logarithmic
Default value is sqrt.
saturation
Set saturation modifier for displayed colors. Negative values
provide alternative color scheme. 0 is no saturation at all.
Saturation must be in [-10.0, 10.0] range. Default value is 1.
win_func
Set window function.
It accepts the following values:
none
No samples pre-processing (do not expect this to be faster)
hann
Hann window
hamming
Hamming window
blackman
Blackman window
Default value is "hann".
The usage is very similar to the showwaves filter; see the examples in
that section.
Examples
· Large window with logarithmic color scaling:
showspectrum=s=1280x480:scale=log
· Complete example for a colored and sliding spectrum per channel
using ffplay:
ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
[a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
showwaves
Convert input audio to a video output, representing the samples waves.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this
option, check the "Video size" section in the ffmpeg-utils manual.
Default value is "600x240".
mode
Set display mode.
Available values are:
point
Draw a point for each sample.
line
Draw a vertical line for each sample.
Default value is "point".
n Set the number of samples which are printed on the same column. A
larger value will decrease the frame rate. Must be a positive
integer. This option can be set only if the value for rate is not
explicitly specified.
rate, r
Set the (approximate) output frame rate. This is done by setting
the option n. Default value is "25".
Examples
· Output the input file audio and the corresponding video
representation at the same time:
amovie=a.mp3,asplit[out0],showwaves[out1]
· Create a synthetic signal and show it with showwaves, forcing a
frame rate of 30 frames per second:
aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
split, asplit
Split input into several identical outputs.
"asplit" works with audio input, "split" with video.
The filter accepts a single parameter which specifies the number of
outputs. If unspecified, it defaults to 2.
Examples
· Create two separate outputs from the same input:
[in] split [out0][out1]
· To create 3 or more outputs, you need to specify the number of
outputs, like in:
[in] asplit=3 [out0][out1][out2]
· Create two separate outputs from the same input, one cropped and
one padded:
[in] split [splitout1][splitout2];
[splitout1] crop=100:100:0:0 [cropout];
[splitout2] pad=200:200:100:100 [padout];
· Create 5 copies of the input audio with ffmpeg:
ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
zmq, azmq
Receive commands sent through a libzmq client, and forward them to
filters in the filtergraph.
"zmq" and "azmq" work as a pass-through filters. "zmq" must be inserted
between two video filters, "azmq" between two audio filters.
To enable these filters you need to install the libzmq library and
headers and configure FFmpeg with "--enable-libzmq".
For more information about libzmq see: <http://www.zeromq.org/>
The "zmq" and "azmq" filters work as a libzmq server, which receives
messages sent through a network interface defined by the bind_address
option.
The received message must be in the form:
<TARGET> <COMMAND> [<ARG>]
TARGET specifies the target of the command, usually the name of the
filter class or a specific filter instance name.
COMMAND specifies the name of the command for the target filter.
ARG is optional and specifies the optional argument list for the given
COMMAND.
Upon reception, the message is processed and the corresponding command
is injected into the filtergraph. Depending on the result, the filter
will send a reply to the client, adopting the format:
<ERROR_CODE> <ERROR_REASON>
<MESSAGE>
MESSAGE is optional.
Examples
Look at tools/zmqsend for an example of a zmq client which can be used
to send commands processed by these filters.
Consider the following filtergraph generated by ffplay
ffplay -dumpgraph 1 -f lavfi "
color=s=100x100:c=red [l];
color=s=100x100:c=blue [r];
nullsrc=s=200x100, zmq [bg];
[bg][l] overlay [bg+l];
[bg+l][r] overlay=x=100 "
To change the color of the left side of the video, the following
command can be used:
echo Parsed_color_0 c yellow | tools/zmqsend
To change the right side:
echo Parsed_color_1 c pink | tools/zmqsend
MULTIMEDIA SOURCES
Below is a description of the currently available multimedia sources.
amovie
This is the same as movie source, except it selects an audio stream by
default.
movie
Read audio and/or video stream(s) from a movie container.
This filter accepts the following options:
filename
The name of the resource to read (not necessarily a file but also a
device or a stream accessed through some protocol).
format_name, f
Specifies the format assumed for the movie to read, and can be
either the name of a container or an input device. If not specified
the format is guessed from movie_name or by probing.
seek_point, sp
Specifies the seek point in seconds, the frames will be output
starting from this seek point, the parameter is evaluated with
"av_strtod" so the numerical value may be suffixed by an IS
postfix. Default value is "0".
streams, s
Specifies the streams to read. Several streams can be specified,
separated by "+". The source will then have as many outputs, in the
same order. The syntax is explained in the ``Stream specifiers''
section in the ffmpeg manual. Two special names, "dv" and "da"
specify respectively the default (best suited) video and audio
stream. Default is "dv", or "da" if the filter is called as
"amovie".
stream_index, si
Specifies the index of the video stream to read. If the value is
-1, the best suited video stream will be automatically selected.
Default value is "-1". Deprecated. If the filter is called
"amovie", it will select audio instead of video.
loop
Specifies how many times to read the stream in sequence. If the
value is less than 1, the stream will be read again and again.
Default value is "1".
Note that when the movie is looped the source timestamps are not
changed, so it will generate non monotonically increasing
timestamps.
This filter allows one to overlay a second video on top of main input
of a filtergraph as shown in this graph:
input -----------> deltapts0 --> overlay --> output
^
|
movie --> scale--> deltapts1 -------+
Examples
· Skip 3.2 seconds from the start of the avi file in.avi, and overlay
it on top of the input labelled as "in":
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
[in] setpts=PTS-STARTPTS [main];
[main][over] overlay=16:16 [out]
· Read from a video4linux2 device, and overlay it on top of the input
labelled as "in":
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
[in] setpts=PTS-STARTPTS [main];
[main][over] overlay=16:16 [out]
· Read the first video stream and the audio stream with id 0x81 from
dvd.vob; the video is connected to the pad named "video" and the
audio is connected to the pad named "audio":
movie=dvd.vob:s=v:0+#0x81 [video] [audio]
SEE ALSOffprobe(1), ffmpeg(1), ffplay(1), ffserver(1), ffmpeg-utils(1),
ffmpeg-scaler(1), ffmpeg-resampler(1), ffmpeg-codecs(1),
ffmpeg-bitstream-filters(1), ffmpeg-formats(1), ffmpeg-devices(1),
ffmpeg-protocols(1), ffmpeg-filters(1)AUTHORS
The FFmpeg developers.
For details about the authorship, see the Git history of the project
(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command git log in
the FFmpeg source directory, or browsing the online repository at
<http://source.ffmpeg.org>.
Maintainers for the specific components are listed in the file
MAINTAINERS in the source code tree.
2014-06-04 FFPROBE-ALL(1)
