[Libav-user] Incorrect md5 for ogg files after ffmpeg version upgrade

Carl Eugen Hoyos cehoyos at ag.or.at
Mon May 9 19:56:34 CEST 2016

Dmitry Bogdanov <dmitry.bogdanov at ...> writes:

> ffmpeg -i test.ogg -acodec copy -f md5 -

You are not the first one doing this, but I have to repeat:
No matter what you are trying to test, this is not guaranteed 
to produce identical output for different versions of FFmpeg.
(Since this was the issue when discussing this last time: 
It is not even guaranteed to produce identical output for 
identical versions of FFmpeg if different compilation options 
were used.)
And (as you found out) the output has changed in the past for 
legitimate changes (or bugfixes). Similar changes are possible 
in the future.

Decoder output is often specified, ie there is a correct output 
that can be compared with actual output. To the best of my 
knowledge, this is not true for decoders, specific output is 
not specified (and not guaranteed by FFmpeg).

> ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers

Unrelated: Note that only current FFmepg git head is supported 

Feel free to explain what you are trying to test. Please 
consider to add what kind of bugs you already found with your 
test or what kind of bugs you would have found if you had 
(already) used the test.

Carl Eugen

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