FFMPEG-CODECS(1)FFMPEG-CODECS(1)NAMEffmpeg-codecs - FFmpeg codecs
DESCRIPTION
This document describes the codecs (decoders and encoders) provided by
the libavcodec library.
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.
sub_id integer
Deprecated, currently unused.
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.
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
libmpeg2mmx
mmi
arm
altivec
sh4
simplearm
simplearmv5te
simplearmv6
simpleneon
simplealpha
h264
vp3
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.
inter_threshold integer (encoding,video)
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
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
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.
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.
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 "-codecs" 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
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".
ENCODERS
Encoders are configured elements in FFmpeg which allow the encoding of
multimedia streams.
When you configure your FFmpeg build, all the supported native encoders
are enabled by default. Encoders requiring an external library must be
enabled manually via the corresponding "--enable-lib" option. You can
list all available encoders using the configure option
"--list-encoders".
You can disable all the encoders with the configure option
"--disable-encoders" and selectively enable / disable single encoders
with the options "--enable-encoder=ENCODER" /
"--disable-encoder=ENCODER".
The option "-codecs" of the ff* tools will display the list of enabled
encoders.
AUDIO ENCODERS
A description of some of the currently available audio encoders
follows.
aac
Advanced Audio Coding (AAC) encoder.
This encoder is an experimental FFmpeg-native AAC encoder. Currently
only the low complexity (AAC-LC) profile is supported. To use this
encoder, you must set strict option to experimental or lower.
As this encoder is experimental, unexpected behavior may exist from
time to time. For a more stable AAC encoder, see libvo-aacenc. However,
be warned that it has a worse quality reported by some users.
Options
b Set bit rate in bits/s. Setting this automatically activates
constant bit rate (CBR) mode.
q Set quality for variable bit rate (VBR) mode. This option is valid
only using the ffmpeg command-line tool. For library interface
users, use global_quality.
stereo_mode
Set stereo encoding mode. Possible values:
auto
Automatically selected by the encoder.
ms_off
Disable middle/side encoding. This is the default.
ms_force
Force middle/side encoding.
aac_coder
Set AAC encoder coding method. Possible values:
0 FAAC-inspired method.
This method is a simplified reimplementation of the method used
in FAAC, which sets thresholds proportional to the band
energies, and then decreases all the thresholds with quantizer
steps to find the appropriate quantization with distortion
below threshold band by band.
The quality of this method is comparable to the two loop
searching method descibed below, but somewhat a little better
and slower.
1 Average noise to mask ratio (ANMR) trellis-based solution.
This has a theoretic best quality out of all the coding
methods, but at the cost of the slowest speed.
2 Two loop searching (TLS) method.
This method first sets quantizers depending on band thresholds
and then tries to find an optimal combination by adding or
subtracting a specific value from all quantizers and adjusting
some individual quantizer a little.
This method produces similar quality with the FAAC method and
is the default.
3 Constant quantizer method.
This method sets a constant quantizer for all bands. This is
the fastest of all the methods, yet produces the worst quality.
Tips and Tricks
According to some reports (e.g.
<http://d.hatena.ne.jp/kamedo2/20120729/1343545890>), setting the
cutoff option to 15000 Hz greatly improves the quality of the output
quality. As a result, we encourage you to do the same.
ac3 and ac3_fixed
AC-3 audio encoders.
These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as
well as the undocumented RealAudio 3 (a.k.a. dnet).
The ac3 encoder uses floating-point math, while the ac3_fixed encoder
only uses fixed-point integer math. This does not mean that one is
always faster, just that one or the other may be better suited to a
particular system. The floating-point encoder will generally produce
better quality audio for a given bitrate. The ac3_fixed encoder is not
the default codec for any of the output formats, so it must be
specified explicitly using the option "-acodec ac3_fixed" in order to
use it.
AC-3 Metadata
The AC-3 metadata options are used to set parameters that describe the
audio, but in most cases do not affect the audio encoding itself. Some
of the options do directly affect or influence the decoding and
playback of the resulting bitstream, while others are just for
informational purposes. A few of the options will add bits to the
output stream that could otherwise be used for audio data, and will
thus affect the quality of the output. Those will be indicated
accordingly with a note in the option list below.
These parameters are described in detail in several publicly-available
documents.
*<<http://www.atsc.org/cms/standards/a_52-2010.pdf>>
*<<http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf>>
*<<http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf>>
*<<http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf>>
Metadata Control Options
-per_frame_metadata boolean
Allow Per-Frame Metadata. Specifies if the encoder should check for
changing metadata for each frame.
0 The metadata values set at initialization will be used for
every frame in the stream. (default)
1 Metadata values can be changed before encoding each frame.
Downmix Levels
-center_mixlev level
Center Mix Level. The amount of gain the decoder should apply to
the center channel when downmixing to stereo. This field will only
be written to the bitstream if a center channel is present. The
value is specified as a scale factor. There are 3 valid values:
0.707
Apply -3dB gain
0.595
Apply -4.5dB gain (default)
0.500
Apply -6dB gain
-surround_mixlev level
Surround Mix Level. The amount of gain the decoder should apply to
the surround channel(s) when downmixing to stereo. This field will
only be written to the bitstream if one or more surround channels
are present. The value is specified as a scale factor. There are 3
valid values:
0.707
Apply -3dB gain
0.500
Apply -6dB gain (default)
0.000
Silence Surround Channel(s)
Audio Production Information
Audio Production Information is optional information describing the
mixing environment. Either none or both of the fields are written to
the bitstream.
-mixing_level number
Mixing Level. Specifies peak sound pressure level (SPL) in the
production environment when the mix was mastered. Valid values are
80 to 111, or -1 for unknown or not indicated. The default value is
-1, but that value cannot be used if the Audio Production
Information is written to the bitstream. Therefore, if the
"room_type" option is not the default value, the "mixing_level"
option must not be -1.
-room_type type
Room Type. Describes the equalization used during the final mixing
session at the studio or on the dubbing stage. A large room is a
dubbing stage with the industry standard X-curve equalization; a
small room has flat equalization. This field will not be written
to the bitstream if both the "mixing_level" option and the
"room_type" option have the default values.
0
notindicated
Not Indicated (default)
1
large
Large Room
2
small
Small Room
Other Metadata Options
-copyright boolean
Copyright Indicator. Specifies whether a copyright exists for this
audio.
0
off No Copyright Exists (default)
1
on Copyright Exists
-dialnorm value
Dialogue Normalization. Indicates how far the average dialogue
level of the program is below digital 100% full scale (0 dBFS).
This parameter determines a level shift during audio reproduction
that sets the average volume of the dialogue to a preset level. The
goal is to match volume level between program sources. A value of
-31dB will result in no volume level change, relative to the source
volume, during audio reproduction. Valid values are whole numbers
in the range -31 to -1, with -31 being the default.
-dsur_mode mode
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby
Surround (Pro Logic). This field will only be written to the
bitstream if the audio stream is stereo. Using this option does NOT
mean the encoder will actually apply Dolby Surround processing.
0
notindicated
Not Indicated (default)
1
off Not Dolby Surround Encoded
2
on Dolby Surround Encoded
-original boolean
Original Bit Stream Indicator. Specifies whether this audio is from
the original source and not a copy.
0
off Not Original Source
1
on Original Source (default)
Extended Bitstream Information
The extended bitstream options are part of the Alternate Bit Stream
Syntax as specified in Annex D of the A/52:2010 standard. It is grouped
into 2 parts. If any one parameter in a group is specified, all values
in that group will be written to the bitstream. Default values are
used for those that are written but have not been specified. If the
mixing levels are written, the decoder will use these values instead of
the ones specified in the "center_mixlev" and "surround_mixlev" options
if it supports the Alternate Bit Stream Syntax.
Extended Bitstream Information - Part 1
-dmix_mode mode
Preferred Stereo Downmix Mode. Allows the user to select either
Lt/Rt (Dolby Surround) or Lo/Ro (normal stereo) as the preferred
stereo downmix mode.
0
notindicated
Not Indicated (default)
1
ltrt
Lt/Rt Downmix Preferred
2
loro
Lo/Ro Downmix Preferred
-ltrt_cmixlev level
Lt/Rt Center Mix Level. The amount of gain the decoder should apply
to the center channel when downmixing to stereo in Lt/Rt mode.
1.414
Apply +3dB gain
1.189
Apply +1.5dB gain
1.000
Apply 0dB gain
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain (default)
0.500
Apply -6.0dB gain
0.000
Silence Center Channel
-ltrt_surmixlev level
Lt/Rt Surround Mix Level. The amount of gain the decoder should
apply to the surround channel(s) when downmixing to stereo in Lt/Rt
mode.
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain
0.500
Apply -6.0dB gain (default)
0.000
Silence Surround Channel(s)-loro_cmixlev level
Lo/Ro Center Mix Level. The amount of gain the decoder should apply
to the center channel when downmixing to stereo in Lo/Ro mode.
1.414
Apply +3dB gain
1.189
Apply +1.5dB gain
1.000
Apply 0dB gain
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain (default)
0.500
Apply -6.0dB gain
0.000
Silence Center Channel
-loro_surmixlev level
Lo/Ro Surround Mix Level. The amount of gain the decoder should
apply to the surround channel(s) when downmixing to stereo in Lo/Ro
mode.
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain
0.500
Apply -6.0dB gain (default)
0.000
Silence Surround Channel(s)
Extended Bitstream Information - Part 2
-dsurex_mode mode
Dolby Surround EX Mode. Indicates whether the stream uses Dolby
Surround EX (7.1 matrixed to 5.1). Using this option does NOT mean
the encoder will actually apply Dolby Surround EX processing.
0
notindicated
Not Indicated (default)
1
on Dolby Surround EX Off
2
off Dolby Surround EX On
-dheadphone_mode mode
Dolby Headphone Mode. Indicates whether the stream uses Dolby
Headphone encoding (multi-channel matrixed to 2.0 for use with
headphones). Using this option does NOT mean the encoder will
actually apply Dolby Headphone processing.
0
notindicated
Not Indicated (default)
1
on Dolby Headphone Off
2
off Dolby Headphone On
-ad_conv_type type
A/D Converter Type. Indicates whether the audio has passed through
HDCD A/D conversion.
0
standard
Standard A/D Converter (default)
1
hdcd
HDCD A/D Converter
Other AC-3 Encoding Options
-stereo_rematrixing boolean
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo
input. This is an optional AC-3 feature that increases quality by
selectively encoding the left/right channels as mid/side. This
option is enabled by default, and it is highly recommended that it
be left as enabled except for testing purposes.
Floating-Point-Only AC-3 Encoding Options
These options are only valid for the floating-point encoder and do not
exist for the fixed-point encoder due to the corresponding features not
being implemented in fixed-point.
-channel_coupling boolean
Enables/Disables use of channel coupling, which is an optional AC-3
feature that increases quality by combining high frequency
information from multiple channels into a single channel. The per-
channel high frequency information is sent with less accuracy in
both the frequency and time domains. This allows more bits to be
used for lower frequencies while preserving enough information to
reconstruct the high frequencies. This option is enabled by default
for the floating-point encoder and should generally be left as
enabled except for testing purposes or to increase encoding speed.
-1
auto
Selected by Encoder (default)
0
off Disable Channel Coupling
1
on Enable Channel Coupling
-cpl_start_band number
Coupling Start Band. Sets the channel coupling start band, from 1
to 15. If a value higher than the bandwidth is used, it will be
reduced to 1 less than the coupling end band. If auto is used, the
start band will be determined by the encoder based on the bit rate,
sample rate, and channel layout. This option has no effect if
channel coupling is disabled.
-1
auto
Selected by Encoder (default)
libmp3lame
LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper.
Requires the presence of the libmp3lame headers and library during
configuration. You need to explicitly configure the build with
"--enable-libmp3lame".
Options
The following options are supported by the libmp3lame wrapper. The
lame-equivalent of the options are listed in parentheses.
b (-b)
Set bitrate expressed in bits/s for CBR. LAME "bitrate" is
expressed in kilobits/s.
q (-V)
Set constant quality setting for VBR. This option is valid only
using the ffmpeg command-line tool. For library interface users,
use global_quality.
compression_level (-q)
Set algorithm quality. Valid arguments are integers in the 0-9
range, with 0 meaning highest quality but slowest, and 9 meaning
fastest while producing the worst quality.
reservoir
Enable use of bit reservoir when set to 1. Default value is 1. LAME
has this enabled by default, but can be overriden by use --nores
option.
joint_stereo (-m j)
Enable the encoder to use (on a frame by frame basis) either L/R
stereo or mid/side stereo. Default value is 1.
libopencore-amrnb
OpenCORE Adaptive Multi-Rate Narrowband encoder.
Requires the presence of the libopencore-amrnb headers and library
during configuration. You need to explicitly configure the build with
"--enable-libopencore-amrnb --enable-version3".
This is a mono-only encoder. Officially it only supports 8000Hz sample
rate, but you can override it by setting strict to unofficial or lower.
Options
b Set bitrate in bits per second. Only the following bitrates are
supported, otherwise libavcodec will round to the nearest valid
bitrate.
4750
5150
5900
6700
7400
7950
10200
12200
dtx Allow discontinuous transmission (generate comfort noise) when set
to 1. The default value is 0 (disabled).
libtwolame
TwoLAME MP2 encoder wrapper.
Requires the presence of the libtwolame headers and library during
configuration. You need to explicitly configure the build with
"--enable-libtwolame".
Options
The following options are supported by the libtwolame wrapper. The
twolame-equivalent options follow the FFmpeg ones and are in
parentheses.
b (-b)
Set bitrate expressed in bits/s for CBR. twolame b option is
expressed in kilobits/s. Default value is 128k.
q (-V)
Set quality for experimental VBR support. Maximum value range is
from -50 to 50, useful range is from -10 to 10. The higher the
value, the better the quality. This option is valid only using the
ffmpeg command-line tool. For library interface users, use
global_quality.
mode (--mode)
Set the mode of the resulting audio. Possible values:
auto
Choose mode automatically based on the input. This is the
default.
stereo
Stereo
joint_stereo
Joint stereo
dual_channel
Dual channel
mono
Mono
psymodel (--psyc-mode)
Set psychoacoustic model to use in encoding. The argument must be
an integer between -1 and 4, inclusive. The higher the value, the
better the quality. The default value is 3.
energy_levels (--energy)
Enable energy levels extensions when set to 1. The default value is
0 (disabled).
error_protection (--protect)
Enable CRC error protection when set to 1. The default value is 0
(disabled).
copyright (--copyright)
Set MPEG audio copyright flag when set to 1. The default value is 0
(disabled).
original (--original)
Set MPEG audio original flag when set to 1. The default value is 0
(disabled).
libvo-aacenc
VisualOn AAC encoder.
Requires the presence of the libvo-aacenc headers and library during
configuration. You need to explicitly configure the build with
"--enable-libvo-aacenc --enable-version3".
This encoder is considered to be worse than the native experimental
FFmpeg AAC encoder, according to multiple sources.
Options
The VisualOn AAC encoder only support encoding AAC-LC and up to 2
channels. It is also CBR-only.
b Set bit rate in bits/s.
libvo-amrwbenc
VisualOn Adaptive Multi-Rate Wideband encoder.
Requires the presence of the libvo-amrwbenc headers and library during
configuration. You need to explicitly configure the build with
"--enable-libvo-amrwbenc --enable-version3".
This is a mono-only encoder. Officially it only supports 16000Hz sample
rate, but you can override it by setting strict to unofficial or lower.
Options
b Set bitrate in bits/s. Only the following bitrates are supported,
otherwise libavcodec will round to the nearest valid bitrate.
6600
8850
12650
14250
15850
18250
19850
23050
23850
dtx Allow discontinuous transmission (generate comfort noise) when set
to 1. The default value is 0 (disabled).
libopus
libopus Opus Interactive Audio Codec encoder wrapper.
Requires the presence of the libopus headers and library during
configuration. You need to explicitly configure the build with
"--enable-libopus".
Option Mapping
Most libopus options are modeled after the opusenc utility from opus-
tools. The following is an option mapping chart describing options
supported by the libopus wrapper, and their opusenc-equivalent in
parentheses.
b (bitrate)
Set the bit rate in bits/s. FFmpeg's b option is expressed in
bits/s, while opusenc's bitrate in kilobits/s.
vbr (vbr, hard-cbr, and cvbr)
Set VBR mode. The FFmpeg vbr option has the following valid
arguments, with the their opusenc equivalent options in
parentheses:
off (hard-cbr)
Use constant bit rate encoding.
on (vbr)
Use variable bit rate encoding (the default).
constrained (cvbr)
Use constrained variable bit rate encoding.
compression_level (comp)
Set encoding algorithm complexity. Valid options are integers in
the 0-10 range. 0 gives the fastest encodes but lower quality,
while 10 gives the highest quality but slowest encoding. The
default is 10.
frame_duration (framesize)
Set maximum frame size, or duration of a frame in milliseconds. The
argument must be exactly the following: 2.5, 5, 10, 20, 40, 60.
Smaller frame sizes achieve lower latency but less quality at a
given bitrate. Sizes greater than 20ms are only interesting at
fairly low bitrates. The default of FFmpeg is 10ms, but is 20ms in
opusenc.
packet_loss (expect-loss)
Set expected packet loss percentage. The default is 0.
application (N.A.)
Set intended application type. Valid options are listed below:
voip
Favor improved speech intelligibility.
audio
Favor faithfulness to the input (the default).
lowdelay
Restrict to only the lowest delay modes.
cutoff (N.A.)
Set cutoff bandwidth in Hz. The argument must be exactly one of the
following: 4000, 6000, 8000, 12000, or 20000, corresponding to
narrowband, mediumband, wideband, super wideband, and fullband
respectively. The default is 0 (cutoff disabled).
libwavpack
A wrapper providing WavPack encoding through libwavpack.
Only lossless mode using 32-bit integer samples is supported currently.
The compression_level option can be used to control speed vs.
compression tradeoff, with the values mapped to libwavpack as follows:
0 Fast mode - corresponding to the wavpack -f option.
1 Normal (default) settings.
2 High quality - corresponding to the wavpack -h option.
3 Very high quality - corresponding to the wavpack -hh option.
4-8 Same as 3, but with extra processing enabled - corresponding to the
wavpack -x option. I.e. 4 is the same as -x2 and 8 is the same as
-x6.
VIDEO ENCODERS
A description of some of the currently available video encoders
follows.
libtheora
Theora format supported through libtheora.
Requires the presence of the libtheora headers and library during
configuration. You need to explicitly configure the build with
"--enable-libtheora".
Options
The following global options are mapped to internal libtheora options
which affect the quality and the bitrate of the encoded stream.
b Set the video bitrate, only works if the "qscale" flag in flags is
not enabled.
flags
Used to enable constant quality mode encoding through the qscale
flag, and to enable the "pass1" and "pass2" modes.
g Set the GOP size.
global_quality
Set the global quality in lambda units, only works if the "qscale"
flag in flags is enabled. The value is clipped in the [0 -
10*"FF_QP2LAMBDA"] range, and then multiplied for 6.3 to get a
value in the native libtheora range [0-63]. A higher value
corresponds to a higher quality.
For example, to set maximum constant quality encoding with ffmpeg:
ffmpeg -i INPUT -flags:v qscale -global_quality:v "10*QP2LAMBDA" -codec:v libtheora OUTPUT.ogg
libvpx
VP8 format supported through libvpx.
Requires the presence of the libvpx headers and library during
configuration. You need to explicitly configure the build with
"--enable-libvpx".
Options
Mapping from FFmpeg to libvpx options with conversion notes in
parentheses.
threads
g_threads
profile
g_profile
vb rc_target_bitrate
g kf_max_dist
keyint_min
kf_min_dist
qmin
rc_min_quantizer
qmax
rc_max_quantizer
bufsize, vb
rc_buf_sz "(bufsize * 1000 / vb)"
rc_buf_optimal_sz "(bufsize * 1000 / vb * 5 / 6)"
rc_init_occupancy, vb
rc_buf_initial_sz "(rc_init_occupancy * 1000 / vb)"
rc_buffer_aggressivity
rc_undershoot_pct
skip_threshold
rc_dropframe_thresh
qcomp
rc_2pass_vbr_bias_pct
maxrate, vb
rc_2pass_vbr_maxsection_pct "(maxrate * 100 / vb)"
minrate, vb
rc_2pass_vbr_minsection_pct "(minrate * 100 / vb)"
minrate, maxrate, vb
"VPX_CBR" "(minrate == maxrate == vb)"
crf "VPX_CQ", "VP8E_SET_CQ_LEVEL"
quality
best
"VPX_DL_BEST_QUALITY"
good
"VPX_DL_GOOD_QUALITY"
realtime
"VPX_DL_REALTIME"
speed
"VP8E_SET_CPUUSED"
nr "VP8E_SET_NOISE_SENSITIVITY"
mb_threshold
"VP8E_SET_STATIC_THRESHOLD"
slices
"VP8E_SET_TOKEN_PARTITIONS"
max-intra-rate
"VP8E_SET_MAX_INTRA_BITRATE_PCT"
force_key_frames
"VPX_EFLAG_FORCE_KF"
Alternate reference frame related
vp8flags altref
"VP8E_SET_ENABLEAUTOALTREF"
arnr_max_frames
"VP8E_SET_ARNR_MAXFRAMES"
arnr_type
"VP8E_SET_ARNR_TYPE"
arnr_strength
"VP8E_SET_ARNR_STRENGTH"
rc_lookahead
g_lag_in_frames
vp8flags error_resilient
g_error_resilient
For more information about libvpx see: <http://www.webmproject.org/>
libx264
x264 H.264/MPEG-4 AVC encoder wrapper.
This encoder requires the presence of the libx264 headers and library
during configuration. You need to explicitly configure the build with
"--enable-libx264".
libx264 supports an impressive number of features, including 8x8 and
4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC
entropy coding, interlacing (MBAFF), lossless mode, psy optimizations
for detail retention (adaptive quantization, psy-RD, psy-trellis).
Many libx264 encoder options are mapped to FFmpeg global codec options,
while unique encoder options are provided through private options.
Additionally the x264opts and x264-params private options allows to
pass a list of key=value tuples as accepted by the libx264
"x264_param_parse" function.
The x264 project website is at
<http://www.videolan.org/developers/x264.html>.
Options
The following options are supported by the libx264 wrapper. The
x264-equivalent options or values are listed in parentheses for easy
migration.
To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see the Codec
Options chapter.
To get a more accurate and extensive documentation of the libx264
options, invoke the command x264 --full-help or consult the libx264
documentation.
b (bitrate)
Set bitrate in bits/s. Note that FFmpeg's b option is expressed in
bits/s, while x264's bitrate is in kilobits/s.
bf (bframes)
g (keyint)
qmax (qpmax)
qmin (qpmin)
qdiff (qpstep)
qblur (qblur)
qcomp (qcomp)
refs (ref)
sc_threshold (scenecut)
trellis (trellis)
nr (nr)
me_range (merange)
me_method (me)
Set motion estimation method. Possible values in the decreasing
order of speed:
dia (dia)
epzs (dia)
Diamond search with radius 1 (fastest). epzs is an alias for
dia.
hex (hex)
Hexagonal search with radius 2.
umh (umh)
Uneven multi-hexagon search.
esa (esa)
Exhaustive search.
tesa (tesa)
Hadamard exhaustive search (slowest).
subq (subme)
b_strategy (b-adapt)
keyint_min (min-keyint)
coder
Set entropy encoder. Possible values:
ac Enable CABAC.
vlc Enable CAVLC and disable CABAC. It generates the same effect as
x264's --no-cabac option.
cmp Set full pixel motion estimation comparation algorithm. Possible
values:
chroma
Enable chroma in motion estimation.
sad Ignore chroma in motion estimation. It generates the same
effect as x264's --no-chroma-me option.
threads (threads)
thread_type
Set multithreading technique. Possible values:
slice
Slice-based multithreading. It generates the same effect as
x264's --sliced-threads option.
frame
Frame-based multithreading.
flags
Set encoding flags. It can be used to disable closed GOP and enable
open GOP by setting it to "-cgop". The result is similar to the
behavior of x264's --open-gop option.
rc_init_occupancy (vbv-init)
preset (preset)
Set the encoding preset.
tune (tune)
Set tuning of the encoding params.
profile (profile)
Set profile restrictions.
fastfirstpass
Enable fast settings when encoding first pass, when set to 1. When
set to 0, it has the same effect of x264's --slow-firstpass option.
crf (crf)
Set the quality for constant quality mode.
crf_max (crf-max)
In CRF mode, prevents VBV from lowering quality beyond this point.
qp (qp)
Set constant quantization rate control method parameter.
aq-mode (aq-mode)
Set AQ method. Possible values:
none (0)
Disabled.
variance (1)
Variance AQ (complexity mask).
autovariance (2)
Auto-variance AQ (experimental).
aq-strength (aq-strength)
Set AQ strength, reduce blocking and blurring in flat and textured
areas.
psy Use psychovisual optimizations when set to 1. When set to 0, it has
the same effect as x264's --no-psy option.
psy-rd (psy-rd)
Set strength of psychovisual optimization, in psy-rd:psy-trellis
format.
rc-lookahead (rc-lookahead)
Set number of frames to look ahead for frametype and ratecontrol.
weightb
Enable weighted prediction for B-frames when set to 1. When set to
0, it has the same effect as x264's --no-weightb option.
weightp (weightp)
Set weighted prediction method for P-frames. Possible values:
none (0)
Disabled
simple (1)
Enable only weighted refs
smart (2)
Enable both weighted refs and duplicates
ssim (ssim)
Enable calculation and printing SSIM stats after the encoding.
intra-refresh (intra-refresh)
Enable the use of Periodic Intra Refresh instead of IDR frames when
set to 1.
b-bias (b-bias)
Set the influence on how often B-frames are used.
b-pyramid (b-pyramid)
Set method for keeping of some B-frames as references. Possible
values:
none (none)
Disabled.
strict (strict)
Strictly hierarchical pyramid.
normal (normal)
Non-strict (not Blu-ray compatible).
mixed-refs
Enable the use of one reference per partition, as opposed to one
reference per macroblock when set to 1. When set to 0, it has the
same effect as x264's --no-mixed-refs option.
8x8dct
Enable adaptive spatial transform (high profile 8x8 transform) when
set to 1. When set to 0, it has the same effect as x264's
--no-8x8dct option.
fast-pskip
Enable early SKIP detection on P-frames when set to 1. When set to
0, it has the same effect as x264's --no-fast-pskip option.
aud (aud)
Enable use of access unit delimiters when set to 1.
mbtree
Enable use macroblock tree ratecontrol when set to 1. When set to
0, it has the same effect as x264's --no-mbtree option.
deblock (deblock)
Set loop filter parameters, in alpha:beta form.
cplxblur (cplxblur)
Set fluctuations reduction in QP (before curve compression).
partitions (partitions)
Set partitions to consider as a comma-separated list of. Possible
values in the list:
p8x8
8x8 P-frame partition.
p4x4
4x4 P-frame partition.
b8x8
4x4 B-frame partition.
i8x8
8x8 I-frame partition.
i4x4
4x4 I-frame partition. (Enabling p4x4 requires p8x8 to be
enabled. Enabling i8x8 requires adaptive spatial transform
(8x8dct option) to be enabled.)
none (none)
Do not consider any partitions.
all (all)
Consider every partition.
direct-pred (direct)
Set direct MV prediction mode. Possible values:
none (none)
Disable MV prediction.
spatial (spatial)
Enable spatial predicting.
temporal (temporal)
Enable temporal predicting.
auto (auto)
Automatically decided.
slice-max-size (slice-max-size)
Set the limit of the size of each slice in bytes. If not specified
but RTP payload size (ps) is specified, that is used.
stats (stats)
Set the file name for multi-pass stats.
nal-hrd (nal-hrd)
Set signal HRD information (requires vbv-bufsize to be set).
Possible values:
none (none)
Disable HRD information signaling.
vbr (vbr)
Variable bit rate.
cbr (cbr)
Constant bit rate (not allowed in MP4 container).
x264opts (N.A.)
Set any x264 option, see x264 --fullhelp for a list.
Argument is a list of key=value couples separated by ":". In filter
and psy-rd options that use ":" as a separator themselves, use ","
instead. They accept it as well since long ago but this is kept
undocumented for some reason.
For example to specify libx264 encoding options with ffmpeg:
ffmpeg -i foo.mpg -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
x264-params (N.A.)
Override the x264 configuration using a :-separated list of
key=value parameters.
This option is functionally the same as the x264opts, but is
duplicated for compability with the Libav fork.
For example to specify libx264 encoding options with ffmpeg:
ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT
Encoding ffpresets for common usages are provided so they can be used
with the general presets system (e.g. passing the pre option).
libxvid
Xvid MPEG-4 Part 2 encoder wrapper.
This encoder requires the presence of the libxvidcore headers and
library during configuration. You need to explicitly configure the
build with "--enable-libxvid --enable-gpl".
The native "mpeg4" encoder supports the MPEG-4 Part 2 format, so users
can encode to this format without this library.
Options
The following options are supported by the libxvid wrapper. Some of the
following options are listed but are not documented, and correspond to
shared codec options. See the Codec Options chapter for their
documentation. The other shared options which are not listed have no
effect for the libxvid encoder.
b
g
qmin
qmax
mpeg_quant
threads
bf
b_qfactor
b_qoffset
flags
Set specific encoding flags. Possible values:
mv4 Use four motion vector by macroblock.
aic Enable high quality AC prediction.
gray
Only encode grayscale.
gmc Enable the use of global motion compensation (GMC).
qpel
Enable quarter-pixel motion compensation.
cgop
Enable closed GOP.
global_header
Place global headers in extradata instead of every keyframe.
trellis
me_method
Set motion estimation method. Possible values in decreasing order
of speed and increasing order of quality:
zero
Use no motion estimation (default).
phods
x1
log Enable advanced diamond zonal search for 16x16 blocks and half-
pixel refinement for 16x16 blocks. x1 and log are aliases for
phods.
epzs
Enable all of the things described above, plus advanced diamond
zonal search for 8x8 blocks, half-pixel refinement for 8x8
blocks, and motion estimation on chroma planes.
full
Enable all of the things described above, plus extended 16x16
and 8x8 blocks search.
mbd Set macroblock decision algorithm. Possible values in the
increasing order of quality:
simple
Use macroblock comparing function algorithm (default).
bits
Enable rate distortion-based half pixel and quarter pixel
refinement for 16x16 blocks.
rd Enable all of the things described above, plus rate distortion-
based half pixel and quarter pixel refinement for 8x8 blocks,
and rate distortion-based search using square pattern.
png
PNG image encoder.
Private options
dpi integer
Set physical density of pixels, in dots per inch, unset by default
dpm integer
Set physical density of pixels, in dots per meter, unset by default
ProRes
Apple ProRes encoder.
FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder.
The used encoder can be choosen with the "-vcodec" option.
Private Options for prores-ks
profile integer
Select the ProRes profile to encode
proxy
lt
standard
hq
4444
quant_mat integer
Select quantization matrix.
auto
default
proxy
lt
standard
hq
If set to auto, the matrix matching the profile will be picked. If
not set, the matrix providing the highest quality, default, will be
picked.
bits_per_mb integer
How many bits to allot for coding one macroblock. Different
profiles use between 200 and 2400 bits per macroblock, the maximum
is 8000.
mbs_per_slice integer
Number of macroblocks in each slice (1-8); the default value (8)
should be good in almost all situations.
vendor string
Override the 4-byte vendor ID. A custom vendor ID like apl0 would
claim the stream was produced by the Apple encoder.
alpha_bits integer
Specify number of bits for alpha component. Possible values are 0,
8 and 16. Use 0 to disable alpha plane coding.
Speed considerations
In the default mode of operation the encoder has to honor frame
constraints (i.e. not produc frames with size bigger than requested)
while still making output picture as good as possible. A frame
containing a lot of small details is harder to compress and the encoder
would spend more time searching for appropriate quantizers for each
slice.
Setting a higher bits_per_mb limit will improve the speed.
For the fastest encoding speed set the qscale parameter (4 is the
recommended value) and do not set a size constraint.
SEE ALSOffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavcodec(3)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.
2013-10-21 FFMPEG-CODECS(1)
