aviindex(1)						      General Commands Manual						       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 exist-
       ing 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 accidently, 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 scan-
		     ning 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 convert 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 "AVIIDX1" 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)