[FFmpeg-trac] #10270(ffmpeg:closed): Random duration changes when transcoding ogg vorbis

[FFmpeg]

#10270: Random duration changes when transcoding ogg vorbis
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             Reporter:  Ace17        |                    Owner:  (none)
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:  ffmpeg
              Version:  unspecified  |               Resolution:  invalid
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Ace17):

 Dear Balling, thanks for your kind answer.

 You were right, I hadn't tested with the HEAD of master.

 So I retried the experiment with a freshly-compiled ffmpeg : HEAD of
 master, at this time of writing, adb5f7b41faf354a3e0bf722f44aeb230aefa310.

 Please note that you have to enable libvorbis at build time (--enable-
 libvorbis), otherwise the problem will not manifest itself.

 Please also note I've added "-acodec libvorbis" on the command line ( to
 prevent FFmpeg from falling back onto the experimental "vorbis"
 implementation from FFmpeg ).

 Here's what I get, still with the same input wav file (bizarre.wav):

 {{{
 + /home/ace/source/ffmpeg/ffmpeg -version
 ffmpeg version N-110043-gadb5f7b41f Copyright (c) 2000-2023 the FFmpeg
 developers
 built with gcc 12 (Debian 12.2.0-14)
 configuration: --enable-libvorbis
 libavutil      58.  4.100 / 58.  4.100
 libavcodec     60.  6.101 / 60.  6.101
 libavformat    60.  4.100 / 60.  4.100
 libavdevice    60.  2.100 / 60.  2.100
 libavfilter     9.  4.100 /  9.  4.100
 libswscale      7.  2.100 /  7.  2.100
 libswresample   4. 11.100 /  4. 11.100
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i bizarre.wav -acodec
 libvorbis -y sound1.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound1.ogg -acodec
 libvorbis -y sound2.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound2.ogg -acodec
 libvorbis -y sound3.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound3.ogg -acodec
 libvorbis -y sound4.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound4.ogg -acodec
 libvorbis -y sound5.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound5.ogg -acodec
 libvorbis -y sound6.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound6.ogg -acodec
 libvorbis -y sound7.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound7.ogg -acodec
 libvorbis -y sound8.ogg
 + /home/ace/source/ffmpeg/ffmpeg -loglevel 1 -i sound8.ogg -acodec
 libvorbis -y sound9.ogg
 + set +x
 sound1.ogg :  Duration: 00:00:01.00, start: 0.000000, bitrate: 106 kb/s
 sound2.ogg :  Duration: 00:00:00.01, start: 0.991293, bitrate: 8928 kb/s
 sound3.ogg :  Duration: 00:00:01.00, start: 0.000000, bitrate: 97 kb/s
 sound4.ogg :  Duration: 00:00:00.99, start: 0.010159, bitrate: 95 kb/s
 sound5.ogg :  Duration: 00:00:00.99, start: 0.010159, bitrate: 97 kb/s
 sound6.ogg :  Duration: 00:00:00.99, start: 0.010159, bitrate: 94 kb/s
 sound7.ogg :  Duration: 00:00:00.99, start: 0.010159, bitrate: 94 kb/s
 sound8.ogg :  Duration: 00:00:01.01, start: 0.000000, bitrate: 96 kb/s
 sound9.ogg :  Duration: 00:00:01.01, start: 0.000000, bitrate: 98 kb/s
 }}}

 Putting aside any concerns about the number of samples in potential
 decoded wav files ...
 ... can we at least agree here that something strange is going on in the
 "start:" and "Duration:" output of ffprobe ? Or maybe am I missing
 something here ?


 Thanks
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10270#comment:2>
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