A/V desync for a vob sample

[Carl Eugen Hoyos]

​http://thread.gmane.org/gmane.comp.video.ffmpeg.user/51659

A user provided a sample to show issues with inverse telecine. The sample shows A/V desync (no matter if an inverse telecine filter is used or not) since 88956f73

$ ffmpeg -i long.sample.vob -qscale 2 -t 25 out.avi
ffmpeg version N-63168-g30cdf38 Copyright (c) 2000-2014 the FFmpeg developers
  built on May 15 2014 21:22:35 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      52. 83.100 / 52. 83.100
  libavcodec     55. 62.100 / 55. 62.100
  libavformat    55. 38.100 / 55. 38.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  5.100 /  4.  5.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
[mpeg2video @ 0x2324940] Invalid frame dimensions 0x0.
    Last message repeated 4 times
Input #0, mpeg, from 'long.sample.vob':
  Duration: 26:24:22.10, start: 611.204267, bitrate: 17 kb/s
    Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, smpte170m), 720x480 [SAR 8:9 DAR 4:3], max. 9800 kb/s, 29.83 fps, 59.94 tbr, 90k tbn, 59.94 tbc
    Stream #0:1[0x80]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
    Stream #0:2[0x81]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0:3[0x1bf]: Data: dvd_nav_packet
    Stream #0:4[0x20]: Subtitle: dvd_subtitle
Please use -q:a or -q:v, -qscale is ambiguous
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf55.38.100
    Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 720x480 [SAR 8:9 DAR 4:3], q=2-31, 200 kb/s, 29.97 tbn, 29.97 tbc
    Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), fltp, 448 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video -> mpeg4)
  Stream #0:1 -> #0:1 (ac3 -> ac3)
Press [q] to stop, [?] for help
[ac3 @ 0x232aa20] frame sync error
Error while decoding stream #0:1: Invalid data found when processing input
frame=  587 fps=0.0 q=2.0 Lsize=    5842kB time=00:00:25.02 bitrate=1912.3kbits/s
video:4440kB audio:1356kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.792863%

[Carl Eugen Hoyos]

Sample uploaded to ​http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket3640/

[Carl Eugen Hoyos]

Works fine with -async 1

[Michael Niedermayer]

Fixed in 3206ea4ba31ebf446a3c4f1220adb895b3272c15