#3871: FFmpeg MD5 output different with same data #2
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Reporter: ahthovaikied | Owner:
Type: defect | Status: new
Priority: normal | Component: avcodec
Version: 2.2.4 | Resolution:
Keywords: md5 aac h264 | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by cehoyos):
Replying to [comment:8 ahthovaikied]:
> OK, it seems we disagree on only one thing:
> You are saying that a demuxer does not necessarily have a bit exact,
reproducible output, and that it could change depending on build options
or CPU, am I correct?
Yes, and the same is true for (at least some) decoders.
Since demuxers can depend on libavcodec, one implies the other.
> Isn't there a standard that precisely describes for example that in a
Matroska file, if byte w has value x, then the chunk from offset y to z is
part of a video stream?
If you have a Matroska file for which libavformat returns broken packets
with a default configuration, please report it here (or on the user
mailing list).
> Replying to [comment:7 cehoyos]:
> > Concerning the bisect: Did you find a version that produces the output
you want and a version that produces a different output on the same system
and with the same compilation options?
> Yes, see my comment above (https://trac.ffmpeg.org/ticket/3871#comment:4
), tests were done on the same core i7 PC, with the same build options.
Sorry, I expected you to write something like "yes, it works with version
x but fails with y". Anyway, please try:
{{{
$ make distclean
$ git bisect reset
$ git bisect start
$ git checkout x
$ git bisect good
$ git checkout y
$ git bisect bad
}}}
Then build and test and depending on the result either use {{{make
distclean && git bisect good}}} or {{{make distclean && git bisect bad}}}
to continue testing and find the version introducing the problem you see.
I run bisects on FFmpeg every day so I can help you if needed, but you may
have to explain how I can reproduce the problem without using a script.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/3871#comment:9>
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