[mythtvnz] Cause of occasional audio/video jumps in playback?

[Matt Poff]

>
> There are two aspects to the issues:
> 1) very slight stutter/jump of audio and video every few seconds.   
> Most
> of the time this is almost imperceptable, however occasionally it gets
> quite noticable.
> 2) the audio drifts slightly in and out of sync over a period of about
> 30 seconds.  Again, quite mild.


That sounds like the same thing. I took a look at the default playback  
profile set on my frontend settings. My machine was set to the CPU+  
setting so I tried switching it over to 'High Quality' - as best I can  
tell from the Wiki page, the key difference of switching to this  
profile is  that ffmpeg rather than XvMC is used to decode the video.  
Anyway, so far no glitches.

 From the docs I could find, a relatively recent Nvidia card like mine  
(7600GS from memory) should be able to manage XvMC decoding (as I  
understand it , a means of handing-off MPEG2 decoding to the GPU). I  
guess the upgrade to 0.21 may have detected the GFX card and switched  
over to XvMC where it was previously set to ffmpeg.

I guess if I was playing high def back or had limited CPU on the MoBo  
then XvMC would be useful but as it is, I don't think it's offering  
any advantage.

More info on the profiles here:
http://www.mythtv.org/wiki/index.php/Playback_profiles#CPU.2B_default_settings