[FFmpeg-trac] #3871(avcodec:new): FFmpeg MD5 output different with same data #2

FFmpeg trac at avcodec.org
Sat Aug 23 12:20:00 CEST 2014

#3871: FFmpeg MD5 output different with same data #2
             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             |

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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