[FFmpeg-devel] [PATCH]lavc/opus: Create extradata if it is missing

[Juan Navarro]

This patch fixes the remuxing of OPUS audio into MP4 container, as per the
issue described here:
http://ffmpeg.org/pipermail/ffmpeg-user/2019-September/045274.html
but introduces a regression for WEBM recordings.

(Originally posted here, with attachments:
http://ffmpeg.org/pipermail/ffmpeg-user/2019-September/045475.html)

I'm afraid some further testing shows that the patch did actually fix
the case of missing extradata when recording OPUS with MP4, but it in
turn breaks the case of WEBM. Didn't try other formats, yet, but there
is a clear regression for the WEBM format.

Report logs attached for both before and after applying the patch. No
meaningful differences in the log, though. The only visible effect of
the regression is when trying to open up the WEBM file in VLC. ffplay is
able to play it, though.

VLC says this when trying to play the WEBM file:
[00007f8978053e20] opus decoder error: cannot read Opus header
[00007f8978053e20] opus decoder error: initial Opus header is corrupted