[mythtv] Digital sound out debugging

[Peter]

OK, I'd like a few pointers if possible to debug a sound issue with the 
Turtle Beach Riviera card. It used to work great, but a recent clean 
wipe and install of FC6 seems to have squashed that. There are several 
others on the user list experiencing this issue as well. I'd be 
perfectly happy debugging the sound problems, but am not sure where to 
start. If someone with some know how can point me in the right 
direction, I'll dig in over the next few weekends and see if I can 
figure out where it's broke.

A quick intro to the problem. Analog works fine, but digital is bad. In 
TV/recording playback, no sound comes out (occasional blips, but nothing 
that lasts). No errors written other than a couple of audio buffer 
prints. Mythmusic plays back files, but it's jittery and the volume is 
somewhat erratic (again, no errors printed). Mplayer doesn't work 
either. aplay works great though (limited as it is). Not sure what all 
this means as I'm a little fuzzy on how sound in Linux works, but I'm 
wondering if something in Alsa changed that hasn't been picked up by 
mplayer or Myth? Or is the Alsa stuff broken? Thanks for any help.

-Pete