[FFmpeg-trac] #9307(undetermined:new): Decoding of Opus audio with missing packets can produce noise spikes

[FFmpeg]

#9307: Decoding of Opus audio with missing packets can produce noise spikes
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             Reporter:  Misaki       |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:  ffplay,      |               Blocked By:
  opus, libopus                      |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Misaki):

 When I play these three files (original, copy.webm and copy.mp4 with just
 audio starting from 0.01) in Firefox on Linux, I get the audio spike with
 the two copies, but not when seeking to the start of the original. Testing
 shows that if video is significantly delayed, like by 0.5 sec, seeking to
 the start of the file goes to its actual start, so in the original file it
 plays from 0 (or possibly -0.007; but ashowinfo says start time is 0), not
 0.02 which is the first video frame.

 So not sure if it would have a noise spike if playback started from 0.01
 or 0.02, or if it's fading in the first 0.01 seconds of audio. Trying to
 seek to around 1% of the playback bar doesn't lead to any such spike.

 The point here is that normal files should not be missing packets. Maybe
 ffmpeg or ffplay could seek to a few audio packets before the playback
 point and discard the decoded output up to that point.
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Ticket URL: <https://trac.ffmpeg.org/ticket/9307#comment:5>
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