[MPlayer-users] Bad audio-video sync with a FLV

Vladimir Mosgalin mosgalin at VM10124.spb.edu
Tue Jul 22 19:57:19 CEST 2008

Hi Nicolas George!

 On 2008.07.22 at 19:03:04 +0200, Nicolas George wrote next:

> of course it diverges again soon. -mc 0, -autosync 1, 30 or 300 do not help.

try also -mc 1 and -mc 0.1
Also -correct-pts sometimes destroys sync (esp. when ivtc filters are
used). So try -no-correct-pts correct-pts was turned on.

-autosync imho is useless, it only helps to solve problems that may
appear with some audio cards / audio output drivers combinations.

> The video stream is declared with a 1 ms timebase. All timestamps are
> multiple of 15 ms, mostly alternating audio and video frames. With ffprobe,
> editing the output to keep only the packet type and pts, I get:

Another thing that can happen with mplayer is incorrect fps reading; in
that case, -fps <real fps value> (with or without -mc) can help

All in all, usually there _is_ some way to play such files in sync. The
question I'm actually interested in, is there way to fix such files with
ffmpeg or mencoder (without re-encoding, of course). When I tried
remuxing .avi which required -mc 0 for correct sync a while ago, the
resulting avi wasn't in sync when played back without -mc 0 too. That's
the most annoying thing about all these sync problems - even if you know
the solution, there is no way to "apply" it permanently.

Strangely enough, recently I've seen even .mkv files which required -mc
to fix sync problems. I used to think it doesn't happen with mkv..



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