[MEncoder-users] Video/Audio asynchronous

[Matthias Hopf]

Nico,

> >or should I upload a sample?
> yes, please

Done. Find it named lavf_copy_broken_audio_hdtv.ts

It's only 1MB, at 1080i, which gives you only approx 1-2 second of video
and audio, but that's enough for the tests. Not for A/V sync issues, but
that is not the case ATM. Let's concentrate on getting it working first,
then I'll test A/V sync again afterwards.


I've done more extensive testing with current unpatched mplayer SVN.
Summary:

- -demuxer lavf breaks -oac copy subtly - still works with mplayer/xine,
  but not on any other player I tried
- remuxing doesn't help
- the extracted ac3 looks good
- the extracted ac3 from the broken avi is exactly the same as the
  extracted ac3 from the original file


Now how I come to this summary:


mencoder -oac copy                  -ovc xvid -xvidencopts 'fixed_quant=4' -o tst0_mpegts.avi lavf_copy_broken_audio_hdtv.ts
mencoder -oac copy    -demuxer lavf -ovc xvid -xvidencopts 'fixed_quant=4' -o tst1_lavf.avi lavf_copy_broken_audio_hdtv.ts
mencoder -oac mp3lame -demuxer lavf -ovc xvid -xvidencopts 'fixed_quant=4' -o tst2_lavf_lame.avi lavf_copy_broken_audio_hdtv.ts
mplayer  -dumpaudio                 -dumpfile tst3_mpegts.ac3 lavf_copy_broken_audio_hdtv.ts
mplayer  -dumpaudio   -demuxer lavf -dumpfile tst4_lavf.ac3 lavf_copy_broken_audio_hdtv.ts
mplayer  -dumpaudio -dumpfile tst5_mpegts_fromavi.ac3 tst0_mpegts.avi
mplayer  -dumpaudio -dumpfile tst6_lavf_fromavi.ac3 tst1_lavf.avi
mencoder -oac copy -ovc copy -o tst7_mpegts_copy.avi tst0_mpegts.avi
mencoder -oac copy -ovc copy -o tst8_lavf_copy.avi tst1_lavf.avi
mplayer  -dumpaudio -dumpfile tst9_lavf_fromcopyavi.ac3 tst7_lavf_copy.avi


The resulting file sizes:

 223242  tst0_mpegts.avi
 232748  tst1_lavf.avi
 221900  tst2_lavf_lame.avi
  26112  tst3_mpegts.ac3
  26112  tst4_lavf.ac3
  24746  tst5_mpegts_fromavi.ac3
  26112  tst6_lavf_fromavi.ac3
 223218  tst7_mpegts_copy.avi
 230184  tst8_lavf_copy.avi
  26112  tst9_lavf_fromcopyavi.ac3

tst0, tst2, tst7: play fine everywhere

tst1, tst8:
 - media player classic (guliverkli), M$ media player 9: no sound (no
   audio detected)
 - virtualdubmod crashes (6 Channel Stereo?!? 17 blocks audio only?!?
   inditerminable length, rate?!?)
 - if I embed one of the .ac3 files with virtualdubmod (disabling the
   already embedded audio) the files play fine (but I won't comment on
   A/V synchronity)
 - mplayer, xine: ok

The .ac3 files tst3, tst4, tst6, and tst9 actually exactly the same, not
only same size. Interestingly, tst5 is different, but it is one of the
files that work.


Please tell me if I can be of any more help.

Matthias

-- 
Matthias Hopf <mhopf at suse.de>       __        __   __
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