aviindex - Write and read text files describing the index of an AVI file
[ -o ofile -i ifile -f
-n -x -v -h
is Copyright (C) 2003,2004 by Tilmann Bitterberg
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.
reads the AVI file ifile
and writes the index into
. This can either happen in "dumb" mode where
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 accidently,
will use the information in this index to recover the keyframe
information, which is important. aviindex
will use smart mode, if given
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
- 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
- Its nice to have for debugging.
- -o ofile
- Specify the name of the output file.
- -i ifile
- Specify the name of the input file.
- force the use of the existing index.
- force generating the index by scanning the file.
- (implies -n) don't use any existing index to generate
- show version.
- show help text.
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
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.
´s format is text based. See FORMAT
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
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
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 seperated 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.
was written by Tilmann Bitterberg <transcode at tibit.org>
and is part of transcode.