[MPlayer-users] Corruption after using -ovc copy

[Nico Sabbi]

On Thursday 13 March 2008 11:20:08 Reimar Döffinger wrote:
> On Thu, Mar 13, 2008 at 11:05:22AM +0100, Haakon Riiser wrote:
> > When cutting parts of a video stream using
> >
> >   -ss <pos> -endpos <x> -ovc copy
> >
> > I often get corruption, as if some P- or B-frames were played
> > without the proper reference frames in the buffer.  I would
> > expect this if -ss allowed me to seek to an arbitrary frame in
> > the stream, but that's not the case at all.  The positions that
> > are seekable using -ss are often far apart, so I'm guessing -ss
> > only seeks to I-frames.
> >
> > If that's the case, why doesn't -ovc copy produce perfect results
> > every time?
>
> You will have to use -mc 0 -noskip or something like that, without
> those it's no wonder it looks like some reference frames are
> missing, because they probably are...

mencoder should at the very least avoid skipping keyframes 
(IIRC where demuxer->video->flags & 1)