[mythtv] AC3 passthrough

[Jason Hoos]

> It's an intel8x0 (ac97) chipset with a C-Media CMI9739 codec, built  
> into my motherboard.  This codec annoys many under Linux for not  
> actually having analog volume control in its mixer, but works 
> fine for SPDIF under ALSA.

Thanks.  I have another machine that might have a chip like this one on it
(not sure), I'll give it a try.  Have you noticed any issues with audio
dropouts on your machine?  I seem to only get the problem on certain
stations, particularly my local ABC affiliate (a 720p station).  I don't
seem to get it on WGN (a 1080i station) though.  And yet, if I play the
recorded files through mplayer, they work fine (last I checked anyways).
It's odd, and I'm wondering if the frame rate of the station has something
to do with it.  I've only begun to dig through the AV sync code in Myth to
see if I can do something about it...

Jason