[MPlayer-users] [BUGS] Problems with MPlayer 1.0pre7 mpeg muxer

[Giacomo Comes]

On Wed, Oct 05, 2005 at 12:42:00PM -0400, Giacomo Comes wrote:
> On Wed, Oct 05, 2005 at 06:24:29PM +0200, Nico Sabbi wrote:
> > Giacomo Comes wrote:
> > 
> > >>>>       
> > >>>>
> > >>>the attached patch should fix the telecine problems.
> > >>>Please, test and report, both with 0/1/2 b-frames.
> > >>>     
> > >>>
> > >>I have done yesterday a quick test with SVCD mpegs
> > >>with 0/1/2 b-frames. The patch works.
> > >>
> > >>I will continue to do tests with DVD and submit a full report
> > >>probably tomorrow.
> > >>   
> > >>
> > >
> > >Ok, here is a full report about the patch.
> > >
> > >What I'm going to say apply to both MPlayer 1.0pre7 and CVS.
> > >
> > >The patch works in the sense that now my DVD player can play
> > >SVCD and DVD that are telecined AND with B-frames.
> > >Without the patch such mpegs created with mencoder plays 
> > >very badly (for example for SVCD the audio plays at normal 
> > >speed and the video plays at 80% speed, about every 15 seconds
> > >the audio stops to let the video come back in sync and then the 
> > >proces repeats).
> > >
> > >But, with the patch applied, I have observed another problem.
> > >I have done a SVCD created with the patched mencoder.
> > >
> > >The playback on my DVD player starts fine but then slowly
> > >the audio anticipates the video. After 1-1.5 minutes
> > >the delay can reach 1 second, and at some point the video 
> > >accelerate to come back in sync.
> > >
> > >I have observed this phenomen with:
> > >telecined mpeg (0 B-frames)
> > >non telecined mpeg (30000/1001 fps) without B-frames
> > >non telecined mpeg (30000/1001 fps) with B-frames
> > >
> > >The same kind of mpegs plays fine on the DVD player if I use 
> > >the unpatched mencoder to create them.
> > >
> > >Of course, in all the cases, mplayer never has problem in playing
> > >such mpegs.
> > >
> > >It would be good if somebody else could test the patch.
> > >I don't think I'm doing something wrong, but it could be.
> > >
> > >Nico, can it be that the patch while fixing a bug, introduces
> > >another one? Or simply make more evident another bug already
> > >present (I was able to see the bug also with the unpatched mencoder 1.0pre7
> > >using no telecine and no B-frames)?
> > >
> > >If you need specific tests please let me know.
> > >
> > >Giacomo
> > 
> > I suspect that mencoder is skipping and duplicating frames, is it?
> > If so try to force it not to do it and see how the resulting video plays 
> > in your dvd.
> 
> I will check this.

Here is the next round of tests.

I'm creating NTSC svcd from a telecined NTSC DVD and I'm checking
when I observe the slow desync (about 1 second per minute)

If I make the mpegs with 30000/1001 fps without letting mencoder 
duplicate frames (using the option -speed) then no desync is observed.
With or without the patch applied and with or without B-frames.

If i make the mpegs with 24000/1001 fps telecined (no duplicated frames)
then there is no desync with the unpatched mencoder, but there is desync
with the patched mencoder. This is valid with or without B-frames.

If I make the mpegs with 30000/1001 fps with duplicated frames
then there is desync without B-frames, no desync with B-frames.
The patch does not make any difference.

All the tests this time were done with 1.0pre7. They are time consuming
so I didn't repeat them using CVS. But if requested, I can repeat all of 
them with CVS (I found a way to make them faster).

What's next?

Giacomo