[MEncoder-users] Fix progressive desynchronization

[Phil Ehrens]

Pepe wrote:
> El Jueves, 14 de Junio de 2007 21:58, Vladimir Mosgalin escribió:
> > Hi Pepe!
> >
> >  On 2007.06.14 at 02:12:37 +0200, Pepe wrote next:
> > > I've got a movie which progressively desynchronizes.
> > >
> > > At the beginning of the movie I have to set the A-V delay to -100. At
> > > half of the movie I have to set it to +700, and at the end to +1300.
> > >
> > > Is there anyway to fix this with mencoder?
> >
> > First, you should discover what exactly is the problem. Most likely
> > mplayer just failes to synchronize the file correctly. Try playing it
> > with -mc 0, -mc 0.1 and -mc 1. There is also -nobps option, a very long
> > time ago it used to help to sometimes, but I haven't seen its uses in
> > ages. Still, try it too.
> 
> Tried with -mc and -nobps but there's no change. I think this video was bad 
> encoded, it happens the same in other players (like xine).

Sometimes, rarely, this is fixed by doing this:

mencoder -oac pcm -ovc copy -ofps 30000/1001

Which should only take a couple of minutes to run. If the
output from that plays properly, then do the same thing,
but re-encode the audio to some compressed format to get
the file size back down (the pcm audio will be huge),
-oac mp3lame, for example.

If that fixes it, then your source was made by concatenating
multiple files together that had different framerates, and
30 fps was either equal to the maximum framrate of the source,
or higher than any framerate in the source. It's a pretty rare
thing to see.