Libavcodec regressions
Xvid Matrix
XVid "Bulletproof's Heavy Compression Matrix" fails in libav, works in FFmpeg.
See https://trac.videolan.org/vlc/ticket/7411 and sample here https://trac.videolan.org/vlc/raw-attachment/ticket/7411/sample.avi
MTS regression
Possibly VLC TS demuxer does not output correct IDR information.
It fails with libav, but works with FFmpeg.
See https://trac.videolan.org/vlc/ticket/10140 and http://streams.videolan.org/issues/10140/MTS%20AVCHD%20Lite%20files%20no%20picture%20bug%20since%20v.2.1.1.MTS
FFv1 v1.3 support
See https://trac.videolan.org/vlc/ticket/9606
The sample here related https://trac.videolan.org/vlc/ticket/8691#no4 is now fixed jb (talk) 16:30, 28 December 2013 (CET)
Lagarith
Totally broken in libav. Numerous reports about that. Waiting for sample. https://forum.videolan.org/viewtopic.php?f=14&t=115983&hilit=lagarith
See https://trac.videolan.org/vlc/ticket/7375 and https://trac.videolan.org/vlc/ticket/9700