[FFmpeg-trac] #9616(ffmpeg:closed): concat of ffmpeg-created opus files defect

[FFmpeg]

#9616: concat of ffmpeg-created opus files defect
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             Reporter:  Wolfgang May  |                    Owner:  (none)
                 Type:  defect        |                   Status:  closed
             Priority:  normal        |                Component:  ffmpeg
              Version:  git-master    |               Resolution:  invalid
             Keywords:  concat opus   |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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Changes (by mkver):

 * status:  new => closed
 * resolution:   => invalid

Comment:

 The packets of most audio codecs (including Opus) can't have an arbitrary
 duration, but can only contain (e.g. decode to) a few discrete values of
 samples, so that there are only a few possible values for the natural
 duration of a packet. While the bitstream can't accurately convey the true
 duration, some containers can and Matroska is one of them. It has the
 "DiscardPadding" element for this purpose: It contains the information how
 many of the samples of the packet are invalid (only inserted by the
 encoder to pad the packet length to one of the permissible values) and
 should be discarded.

 Your error message indicates that Firefox doesn't support DiscardPadding
 unless it is at the very last packet. This is a bug in Firefox.

 I don't know a good workaround for this; the least bad option I can think
 of is to trim the last audio frame of all non-last files away.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9616#comment:2>
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