[MEncoder-users] Audio/Video out-of-sync when using the "-noskip -mc 0"

[Rich Felker]

On Fri, Jul 07, 2006 at 07:11:20PM +0800, Tsz Ming WONG wrote:
> Hi,
> 
> When using the option : "-noskip -mc 0" in converting a wmv file to a flv
> file, I found that the audio stream is a little bit faster then the video
> stream...
> 
> COMMAND:
> 
> /usr/local/mplayer/bin/mencoder tv.wmv -o tv.flv -of lavf -oac mp3lame
> -lameopts abr:br=32 -ovc lavc -lavcopts
> vcodec=flv:vbitrate=300:cbp:mv0:mbd=2:trell:v4mv:predia=2:dia=2:last_pred=3
> -srate 22050 -noskip -mc 0 -ofps 25
> 
> 
> However, when I removed the "-noskip -mc 0", the result flv is okay (correct
> a/v synchronization).

Of course -noskip -mc 0 will give a/v desync unless the input frames
exactly match the chosen output framerate. What else could it do?

My guess is that you've chosen the wrong output framerate. Either the
wmv file is a different framerate or it's "supposed to be 25" but
slightly off. Since wmv doesn't have a nominal framerate or timebase,
only millisecond timestamps, you'll have to play around and guess the
framerate until you get one that works, or give up on using -noskip
and -mc 0.

Rich