[MEncoder-users] A/V synchronization problem using mencoder

[D Richard Felker III]

On Tue, Mar 29, 2005 at 01:53:30PM +0200, Oded Shimon wrote:
> On Tue, Mar 29, 2005 at 12:01:33PM +0200, Guillaume Poirier wrote:
> > Hi,
> > 
> > 
> > On Tue, 29 Mar 2005 05:37:18 +0200, Oded Shimon <ods15 at ods15.dyndns.org> wrote:
> > > On Tue, Mar 29, 2005 at 11:08:21AM +0800, Xie Bo wrote:
> > > > Hi,
> > > >
> > > >    I compiled the MPlayer-20050324 CVS in MinGW and run the following commond:
> > > > --------
> > > > mplayer dvd://
> > > > --------
> > > >    It is synchronized.
> > > >
> > > >    But when I execute the following command:
> > > > ----------
> > > > mencoder dvd:// -of mpeg -o output.mpg -oac copy -ovc copy -mpegopts format=dvd
> > > > mplayer output.mpg
> > > > ----------
> > > 
> > > Try adding to the mencoder command '-mc 0 -noskip'.
> > > Might help.
> > 
> > Out of curiosity, why aren't those options on by default when using
> > MEncoder? I can't find too many use cases when the user doesn't care
> > about frames getting discarded, all the more when it leads to desync.
> > Ok, that might be useful for real time conversion... Are there any
> > others?
> 
> In most cases (when creating an AVI), adding thse options will CAUSE a desync, 
> not prevent it. This is MEncoder's broken way of dealing with A/V sync in 
> files. It's fundementaly wrong, but it works.

If -mc 0 and -noskip change anything, they will CAUSE desync, not fix
it. Unless it's just a matter of fixing a few broken spots where you
get a duplicate followed by a skip or vice versa. The -noskip option
is especially broken and bad to use, and you really should never use
either unless you understand exactly what you're doing.

Anyway this whole commandline is stupid. There are proper tools for
copying a DVD to hard drive. Remuxing it is very bad since you'll lose
the subtitles, etc.

Rich