Opus decoding glitches on sample with LBRR packets

[Tristan Matthews]

Summary of the bug:

Using ​https://people.videolan.org/~tmatth/rev.opus when stream-copied or played back.

How to reproduce:

% ./ffplay rev.opus
./ffplay rev.opus
ffplay version N-107861-gf5a663f2a9 Copyright (c) 2003-2022 the FFmpeg developers
  built with gcc 11 (Ubuntu 11.2.0-19ubuntu1)
  configuration: --disable-debug --disable-doc --disable-shared --enable-gpl --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libx264 --enable-nonfree --enable-gnutls --enable-libfdk_aac --enable-postproc --enable-small --enable-version3 --enable-libx265 --enable-libsrt --prefix=/home/tmatth/local
  libavutil      57. 33.101 / 57. 33.101
  libavcodec     59. 42.102 / 59. 42.102
  libavformat    59. 30.100 / 59. 30.100
  libavdevice    59.  8.101 / 59.  8.101
  libavfilter     8. 46.103 /  8. 46.103
  libswscale      6.  8.103 /  6.  8.103
  libswresample   4.  8.100 /  4.  8.100
  libpostproc    56.  7.100 / 56.  7.100
Input #0, ogg, from 'rev.opus':    0KB vq=    0KB sq=    0B f=0/0   
  Duration: 00:00:06.00, start: 0.000000, bitrate: 64 kb/s
  Stream #0:0(eng): Audio: opus, 48000 Hz, stereo, fltp
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2avc1mp41
      encoder         : Lavf58.76.100

Note that:

./ffplay -acodec libopus rev.opus

doesn't glitch but also that this happens with streamcopying via ffmpeg as well (so not specific to ffplay).

The file plays fine with VLC, totem, and opusdec also decodes it to wav without any glitches.

[Tristan Matthews]

Sample that demonstrates the bug

[Tristan Matthews]

This may be related to ​https://trac.ffmpeg.org/ticket/4641 as the glitches are happening on LBRR frames only.

[MarkZV]

It looks like the code that was added to decode and skip the LBRR frames needs to at least reset the midonly flag afterwards.

[Tristan Matthews]

I've submitted a patch here:
​http://ffmpeg.org/pipermail/ffmpeg-devel/2022-August/300758.html

[Tristan Matthews]

I've submitted Sample with LBRR packets that could be incorporated into FATE.

[Tristan Matthews]

Example of current glitchy decoding with master

[Tristan Matthews]

Example of decoding with midonly flag being reset

[Tristan Matthews]

Added fate test + samples:

​https://people.videolan.org/~tmatth/9890-fate/

Patch for fate sent:
https://ffmpeg.org/pipermail/ffmpeg-devel/2022-September/301164.html

[Balling]

Fixed in e301143f96639b97a8e9a0045f93b56e0f399289.