[mythtv] Reasonable avsync at startup
ijr at po.cwru.edu
Sun Aug 29 11:38:20 EDT 2004
On Sunday 29 August 2004 10:50 am, Doug Larrick wrote:
> Bruce Markey wrote:
> > One thing it shows is a long standing problem (at least pre-0.6!)
> > with the need to slew a lot at startup before audio and video
> > come into sync. It would be great if you could look into this
> > to help make the best possible DVR for all of us =).
> > It seems that audio time and video time are initially set relative
> > to the system clock. However, video is almost always way ahead
> > of audio by tens of frames and has to wait for audio to catch up.
> From some experimentation this morning, it appears that the issue here
> is that when audioout comes out of pause, it still has to play the
> soundcard's entire buffer (full of zeros) before it gets around to
> playing the audio we just gave it. My soundcard has a 64k buffer, so
> for normal audio that's just over half a second. The best fix would
> probably be to clear out this buffer when coming out of audio pause;
> alternatively video could wait until audio hits the target time until
Does the 'Aggressive soundcard buffering' setting help at all in this regard?
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