[FFmpeg-trac] #11423(undetermined:new): Remuxing webm to opus adds silence to opus stream

[FFmpeg]

#11423: Remuxing webm to opus adds silence to opus stream
-------------------------------------+-------------------------------------
             Reporter:  y1dj1sqd     |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  webm opus    |               Blocked By:
  remux                              |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 When extracting the opus stream from a .webm file to a .opus file it does
 change the duration of the opus stream.

 The extracted stream starts delayed and it adds some additional silence to
 the end.

 How to reproduce:
 {{{

 % yt-dlp -f 251 "https://www.youtube.com/watch?v=dQw4w9WgXcQ"

 % ffmpeg -i "Rick Astley - Never Gonna Give You Up (Official Music Video)
 [dQw4w9WgXcQ].webm" -c copy out.opus

 }}}

 For comparison doing the same with mkvextract does output a stream which
 is perfectly in sync and the exact same duration as the input:
 {{{
 % mkvextract "Rick Astley - Never Gonna Give You Up (Official Music Video)
 [dQw4w9WgXcQ].webm" tracks 0:out2.opus
 }}}

 ffmpeg versions tested (both affected)
 {{{
 ffmpeg version n7.1 Copyright (c) 2000-2024 the FFmpeg developers
 }}}
 {{{
 ffmpeg version N-118315-g4f3c9f2f03-20250116 Copyright (c) 2000-2025 the
 FFmpeg developers
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11423>
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