


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



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aviindex(1)                                           aviindex(1)


                     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 \



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aviindex(1)                                           aviindex(1)


            -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.




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aviindex(1)                                           aviindex(1)


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)





















































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