[FFmpeg-trac] #3440(undetermined:new): vp8: a/v desync on seek with -auto-alt-ref 1

[FFmpeg]

#3440: vp8: a/v desync on seek with -auto-alt-ref 1
-------------------------------------+-------------------------------------
             Reporter:  blacktrash   |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:  libvpx       |               Blocked By:
  auto-alt-ref                       |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 How to reproduce:
 {{{
 $ffmpeg -i BigBuckBunny_640x360.m4v -f webm -c:v libvpx -auto-alt-ref 1
 -b:v 300k -c:a libvorbis -b:a 64k -pass 1 test.webm
 ffmpeg version N-61061-gf34cceb Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Mar  4 2014 10:23:19 with Apple LLVM version 5.0
 (clang-500.2.79) (based on LLVM 3.3svn)
   configuration: --enable-gpl --enable-version3 --enable-nonfree
 --disable-ffserver --enable-shared --enable-libfdk-aac --enable-libx265
 --enable-libx264 --enable-libxvid --enable-libfaac --enable-libmp3lame
 --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp
 --extra-cflags=-I/sw/include --extra-libs=-L/sw/lib
   libavutil      52. 66.101 / 52. 66.101
   libavcodec     55. 52.102 / 55. 52.102
   libavformat    55. 33.101 / 55. 33.101
   libavdevice    55. 11.100 / 55. 11.100
   libavfilter     4.  2.100 /  4.  2.100
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 18.100 /  0. 18.100
   libpostproc    52.  3.100 / 52.  3.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'BigBuckBunny_640x360.m4v':
   Metadata:
     major_brand     : M4V
     minor_version   : 1
     compatible_brands: M4V M4A mp42isom
     creation_time   : 2008-06-03 05:23:28
     copyright       : © 2008 Blender Foundation | www.bigbuckbunny.org
     title           : Big Buck Bunny
     artist          : Peach Open Movie Team
     composer        : Sacha Goedegebure / Ton Roosendaal
     date            : 2008
   Duration: 00:09:56.46, start: 0.000000, bitrate: 1626 kb/s
     Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo,
 fltp, 127 kb/s (default)
     Metadata:
       creation_time   : 2008-06-03 05:23:28
       handler_name    : Apple Sound Media Handler
     Stream #0:1(eng): Video: h264 (Constrained Baseline) (avc1 /
 0x31637661), yuv420p(tv, smpte170m), 640x360, 1495 kb/s, 24 fps, 24 tbr,
 2400 tbn, 4800 tbc (default)
     Metadata:
       creation_time   : 2008-06-03 05:23:28
       handler_name    : Apple Video Media Handler
 [libvpx @ 0x7f9e32801e00] v1.3.0-1648-g91e5e5a
 Output #0, webm, to 'test.webm':
   Metadata:
     major_brand     : M4V
     minor_version   : 1
     compatible_brands: M4V M4A mp42isom
     date            : 2008
     copyright       : © 2008 Blender Foundation | www.bigbuckbunny.org
     title           : Big Buck Bunny
     artist          : Peach Open Movie Team
     composer        : Sacha Goedegebure / Ton Roosendaal
     encoder         : Lavf55.33.101
     Stream #0:0(eng): Video: vp8 (libvpx), yuv420p, 640x360, q=-1--1, pass
 2, 300 kb/s, 1k tbn, 24 tbc (default)
     Metadata:
       creation_time   : 2008-06-03 05:23:28
       handler_name    : Apple Video Media Handler
     Stream #0:1(eng): Audio: vorbis (libvorbis), 44100 Hz, stereo, fltp,
 64 kb/s (default)
     Metadata:
       creation_time   : 2008-06-03 05:23:28
       handler_name    : Apple Sound Media Handler
 Stream mapping:
   Stream #0:1 -> #0:0 (h264 -> libvpx)
   Stream #0:0 -> #0:1 (aac -> libvorbis)
 Press [q] to stop, [?] for help
 frame=14316 fps= 44 q=0.0 Lsize=   26255kB time=00:09:56.50 bitrate=
 360.6kbits/s
 video:21847kB audio:4094kB subtitle:0 data:0 global headers:4kB muxing
 overhead 1.196710%
 }}}

 And same for -pass 2 produces a result where video and audio lose sync
 when seeking, be it in mplayer or in a html5 video tag. The problem is
 triggered by -auto-alt-ref 1, which is also in every libvpx preset.
 Omitting that option avoids the issue.

 Happens with all input videos I've tried so far.

 Aside: I would expect -auto-alt-ref 0 after -vpre to unset auto-alt-ref
 from the preset, but it does not:
 {{{
  ffmpeg -i BigBuckBunny_640x360.m4v -f webm -vpre libvpx-360p -b:v 300k
 -auto-alt-ref 0 -c:a libvorbis -b:a 64k
  -pass 1 test.webm
 }}}
 also exhibits the problem, whereas giving all options except auto-alt-ref
 on the commandline again circumvents it.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3440>
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