[mythtv] analysis of A/V sync problem

Marcel Janssen korgull at home.nl
Sat Mar 12 17:35:28 UTC 2005


Hi,

Ever since I've installed mythtv 0.17 I'm having serious A/V sync problems in 
live TV and playback of recordings. I've reported about this on mythtv-user, 
but unfortunately nobody has come up with a solution on it.
Since none of the options or updates of (audio)drivers did anything to get it 
better I suspected a bug in mythtv which caused this behaviour on my system.

Since mythtv 0.16 didn't have this problem I've started to trace back through 
CVS which version still worked for me and which version causes the A/V sync 
problem on my system. The problem I'm having is that A/V sync is as far as 2 
seconds off (mostly audio is there before video).

I managed to close things down by a day now.

mythtv from 2004-11-11 doesn't have A/V sync problems
mythtv from 2004-11-12 has the A/V sync problem

The version from 2004-11-11 however has some dropouts in audio which I don't 
have with the version from 2004-11-12.
Note that I don't have any audio or video problems with applications like xine 
or mplayer which makes me believe that the audio driver is not the problem 
here (although that's not 100% sure of course).

Does this trigger anyone on a specific part of code that may cause my 
problem ?

I can trace further by time of the day, but I hope someone is triggered by the 
above and has some idea what the root cause may be (mythtv compiling takes 
very long, this analysis took me already most of the day ;-) )

I use audio through SPDIF from a dxr3 card.

Regards,
Marcel Janssen




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