Initial A/V desync when remuxing or transcoding ASP / MP3 in avi

[Carl Eugen Hoyos]

​http://www.datafilehost.com/download-eedefa35.html

The sample plays fine with ffplay and MPlayer, if remuxed (to avi) or transcoded, the resulting video shows constant A/V desync (audio too early) from the beginning.

The following scenes can be used to see the desync:
~ 65 seconds: A trigger is pulled and a light ignites
~ 110 seconds: Footsteps can be heard and seen
And from 120 seconds on

out.avi shows ~1 second desync:

$ ffmpeg -i avdesync.avi -qscale 2 -r 24000/1001 -t 145 out.avi
ffmpeg version N-32916-g73a5287, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep 25 2011 12:04:12 with gcc 4.5.3
  configuration: --enable-libvpx --enable-libvorbis --cc=/usr/local/gcc-4.5.3/bin/gcc
  libavutil    51. 17. 0 / 51. 17. 0
  libavcodec   53. 17. 0 / 53. 17. 0
  libavformat  53. 13. 0 / 53. 13. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 43. 5 /  2. 43. 5
  libswscale    2.  1. 0 /  2.  1. 0
[mp3 @ 0x12cb7a0] Header missing

Seems stream 0 codec frame rate differs from container frame rate: 23.98 (65535/2733) -> 23.98 (2500000/104271)
Input #0, avi, from 'avdesync.avi':
  Metadata:
    encoder         : VirtualDubMod 1.5.10.2 (build 2540/release)
  Duration: 01:54:18.98, start: 0.000000, bitrate: 69 kb/s
    Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 720x304 [SAR 1:1 DAR 45:19], 23.98 fps, 23.98 tbr, 23.98 tbn, 23.98 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, s16, 128 kb/s
[buffer @ 0x12eb0c0] w:720 h:304 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param:
Incompatible sample format 's16' for codec 'ac3', auto-selecting format 'flt'
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf53.13.0
    Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 720x304 [SAR 1:1 DAR 45:19], q=2-31, 200 kb/s, 23.98 tbn, 23.98 tbc
    Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo, flt, 128 kb/s
Stream mapping:
  Stream #0.0 -> #0.0 (mpeg4 -> mpeg4)
  Stream #0.1 -> #0.1 (mp3 -> ac3)
Press [q] to stop, [?] for help
[mp3 @ 0x12cb7a0] Header missing
Error while decoding stream #0.1
frame= 3475 fps=302 q=2.0 Lsize=   66122kB time=00:02:24.00 bitrate=3761.6kbits/s
video:63673kB audio:2250kB global headers:0kB muxing overhead 0.300935%

out2.avi shows ~0.7 seconds desync:

$ ffmpeg -i avdesync.avi -vcodec copy -acodec copy -r 24000/1001 -t 145 out2.avi
ffmpeg version N-32916-g73a5287, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep 25 2011 12:04:12 with gcc 4.5.3
  configuration: --enable-libvpx --enable-libvorbis --cc=/usr/local/gcc-4.5.3/bin/gcc
  libavutil    51. 17. 0 / 51. 17. 0
  libavcodec   53. 17. 0 / 53. 17. 0
  libavformat  53. 13. 0 / 53. 13. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 43. 5 /  2. 43. 5
  libswscale    2.  1. 0 /  2.  1. 0
[mp3 @ 0x12cb7a0] Header missing

Seems stream 0 codec frame rate differs from container frame rate: 23.98 (65535/2733) -> 23.98 (2500000/104271)
Input #0, avi, from 'avdesync.avi':
  Metadata:
    encoder         : VirtualDubMod 1.5.10.2 (build 2540/release)
  Duration: 01:54:18.98, start: 0.000000, bitrate: 69 kb/s
    Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 720x304 [SAR 1:1 DAR 45:19], 23.98 fps, 23.98 tbr, 23.98 tbn, 23.98 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, s16, 128 kb/s
Output #0, avi, to 'out2.avi':
  Metadata:
    ISFT            : Lavf53.13.0
    Stream #0:0: Video: mpeg4 (XVID / 0x44495658), yuv420p, 720x304 [SAR 1:1 DAR 45:19], q=2-31, 23.98 tbn, 23.98 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, 128 kb/s
Stream mapping:
  Stream #0.0 -> #0.0 (copy)
  Stream #0.1 -> #0.1 (copy)
Press [q] to stop, [?] for help
frame= 3477 fps=  0 q=-1.0 Lsize=   58404kB time=00:02:25.00 bitrate=3299.4kbits/s
video:55905kB audio:2266kB global headers:0kB muxing overhead 0.401601%

I will upload the beginning of the sample: Audio gets significantly quieter too early.

[Carl Eugen Hoyos]

Works fine with -async 1.

[Carl Eugen Hoyos]

This appears to have been fixed.