[MPlayer-advusers] Dirac demuxing A/V sync loss

[Uoti Urpala]

On Fri, 2008-10-17 at 18:00 +0400, Andrew Savchenko wrote:
> A sample plays with -demuxer lavf, but video quickly runs out of 
> sync, and I get a huge bunch of
> pts value <= previous
> messages.
> 
> I managed to maintain A/V sync using -mc 100 -autosync 40, but this 
> leads to regular framedrops and choppy video playback whilst a lot 
> of CPU available.
> 
> This file plays perfectly with ffplay, so I suspect a bug somewhere 
> around libmpdemux/demux_lavf.c code.

The problem is caused by the libavcodec decoder. It leaves has_b_frames
at 0 which is incorrect. This confuses the MPlayer timing code. If I
force the code to assume a decode delay of 1 instead of the 0 claimed by
the decoder then it seems to play OK.