I'm posting this for my future self (to help me remember what to do). Maybe it will help someone else:
Installed Mythbuntu 12.04 on a system with NVidia GT240 or there abouts.
Myth now has a cool audio setup that worked slick but it talks straight to the alsa device you select. I forgot to set a system default device. Tried to play a movie in the browser. Ack! Kids cheezed. No audio. Panic time. How does alsa work again?
Shows all the possible devices.
I know I had picked one that worked in myth. Popped in and saw it was something about CARD=NVIDIA_1, DEV=1.
The aplay -L list had this entry:
That must be it. So did:
HDA NVidia, HDMI 0
HDMI Audio Output
Since my Samsung TV is 2 channel audio (YMMV) and got the nice audio test noise. It worked. So:
speaker-test -c 2 -D hdmi:CARD=NVidia_1,DEV=1
Then made typed this:
sudo nano asound.conf
Saved the file. I can't figure out how to restart the sound subsystem. Seems to not matter. Cool.
Did a speaker test with the default device:
Desktop audio restored. Party on.
Future Dewey, dang your brain is turning to mush. Hopefully this will help you.