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aviindex(1)							   aviindex(1)

NAME
       aviindex	 -  Write  and	read text files describing the index of an AVI
       file

SYNOPSIS
       aviindex [ -o ofile -i ifile -f -n -x -v -h ]

COPYRIGHT
       aviindex is Copyright (C) 2003,2004 by Tilmann Bitterberg

DESCRIPTION
       aviindex writes a text file describing the index of  an	AVI  file.  It
       analyses	 the  content or index if available of the AVI file and prints
       this information in a human readable form.

       An AVI file can have an optional chunk  called  "idx1"  which  contains
       information  about keyframes (syncpoints) and locations of video frames
       resp. audio chunks. Though larger AVI files (>2-4GB), so-called OpenDML
       AVI or also AVI 2 files, have a more complicated indexing system, which
       consists of a superindex referring  to  (possibly)  several  "standard"
       indexes,	 the "indexing principle" is the same.	Movie players use such
       indexes to seek in files.

       aviindex reads the AVI file ifile and writes the index into ofile. This
       can  either  happen in "dumb" mode where aviindex looks for an existing
       index (and trusts this index!)  in the file and dumps this index into a
       human  readable form. The "dumb" mode is used, when -n is NOT specified
       or when the filesize of the input file is smaller than 2 GB.

       In "smart" mode, aviindex scans	through	 the  complete	AVI  file  and
       searches	 for  chunks  (may  that  video or audio) and reconstructs the
       index based on the information found. If an index chunk is found	 acci‐
       dently,	aviindex will use the information in this index to recover the
       keyframe information, which is important. aviindex will use smart mode,
       if  given  the -n option OR if the AVI file is larger than 2 GB. If the
       file is large, the index chunk cannot be found the  usual  way  so  one
       must  use  -n  but  it is possible that there is an index chunk in this
       file. Cross fingers.

       Also in smart mode, aviindex analyzes the content of  the  video	 frame
       and  tries  to detect keyframes by looking at the data depending on the
       video codec.

       The generated index file serves different purposes.

	      *	     The library which handles AVI files in  transcode(1)  can
		     read  such	 index	files and use this file to rebuild the
		     index instead of scanning through the whole AVI file over
		     and  over again. Reading the index from the index file is
		     much faster than scanning through the AVI.

	      *	     It can be used as a seeking file. When given to transcode
		     via the --nav_seek switch, transcode will use the file to
		     seek directly to the position you specified via -c.  This
		     also works for multiple -c ranges.

	      *	     Its nice to have for debugging.

OPTIONS
       -o ofile
	      Specify the name of the output file.

       -i ifile
	      Specify the name of the input file.

       -f     force the use of the existing index.

       -n     force generating the index by scanning the file.

       -x     (implies -n) don't use any existing index to generate keyframes.

       -v     show version.

       -h     show help text.

MPLAYER
       aviindex	 can  convert from and to mplayer-generated index files. Since
       mplayer-1.0pre3 mplayer has the ability to save the index via  -saveidx
       FILE and load it again through -loadidx FILE.  aviindex is able to con‐
       vert an mplayer index file to a transcode index file and vice visa.  It
       is  not	able  to  directly write an mplayer file, though. Example of a
       toolchain
	 mplayer -frames 0 -saveidx mpidx broken.avi
	 aviindex -i mpidx -o tcindex
	 avimerge -x tcindex -i broken.avi -o fixed.avi
       Or the other way round
	 aviindex -i broken.avi -n -o broken.idx
	 aviindex -i broken.idx -o mpidx
	 mplayer -loadidx mpidx broken.avi
       The major differences between the two index file formats	 is  that  the
       mplayer	one  is	 a binary format which is an exact copy of an index in
       the AVI file.  aviindex	´s  format  is	text  based.  See  FORMAT  for
       details.

EXAMPLES
       The command

	 aviindex -i 3GBfile.avi -o 3GB.index

       generates and index of the large file 3GBfile.avi. You can use the file
       3GB.index to tell transcode to read the index from this	file  and  not
       from the avi. This leads to much faster startup time.

       Suppose 3GBfile.avi has DivX video and PCM sound and you want to encode
       several ranges.

       transcode -V -i 3GBfile.avi --nav_seek 3GB.index \
	    -x xvid,avi \
	    -c 5000-6000,0:20:00-0:21:00,100000-100001 \
	    -y xvid --lame_preset standard -o out.avi

FORMAT
       The format of the index file. The first 7 bytes in this file are	 "AVI‐
       IDX1"  for  easy	 detection and a comment of who created the file.  The
       second line is a comment and describes the fields. Do  not  delete  it.
       Each  line (except the first 2) consists of exactly 8 fields all seper‐
       ated by one space and describing one particular chunk of the AVI file.
       Here is an example of an AVI file with two audio tracks.

	      AVIIDX1 # Generated by aviindex (transcode-0.6.8)
	      TAG TYPE CHUNK CHUNK/TYPE POS LEN KEY MS
	      00db 1 0 0 2048 8335 1 0.00
	      01wb 2 1 0 10392 847 1 0.00
	      01wb 2 2 1 11248 847 1 0.00
	      02wb 3 3 0 12104 847 1 0.00
	      02wb 3 4 1 12960 847 1 0.00
	      00db 1 5 1 13816 5263 0 0.00
	      00db 1 6 2 19088 3435 0 0.00
	      01wb 2 7 2 22532 834 1 0.00

       The field TAG is the chunk descriptor. Its "00d*" for the video, "01wb"
       for the first audio track, "02wb" for the second audio track and so on.

       The  field TYPE is the type of the chunk. This is redundant because the
       type is also embedded into the TAG field but its a convenient thing  to
       have.  Its  1 for video, 2 for first audio track and 3 for second audio
       track.

       The field CHUNK is the absolute chunk number in the AVI	file.  If  you
       read  the  CHUNK field in the last line of the index file, you know how
       many chunks this AVI file has.

       The field CHUNK/TYPE holds information about how many  chunks  of  this
       type were previously found in the AVI file.

       The  field POS is the absolute byte position in the AVI file where this
       chunk can be found. Note this field can hold really  large  numbers  if
       you are dealing with large AVIs.

       The field LEN is the length of this chunk.

       The  field  KEY	holds information if this chunk is a keyframe.	In the
       example above, all audio chunks are  key-chunks,	 but  only  the	 first
       video frame is a key frame. This field is either 0 or 1.

       The field MS holds information about how many milliseconds have passed.
       This field may be 0.00 if unknown.

AUTHORS
       aviindex was written by Tilmann Bitterberg <transcode at tibit.org>
       and is part of transcode.

SEE ALSO
       avifix(1), avisync(1), avimerge(1), avisplit(1), tccat(1), tcdecode(1),
       tcdemux(1),    tcextract(1),   tcprobe(1),   tcscan(1),	 transcode(1),
       mplayer(1)

aviindex(1)		      29th February 2004		   aviindex(1)
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