I spend a lot of time getting HDMI audio working with my Asus M3N78-EM and Ubuntu 9.04. I posted this on the ubuntuforums.org earlier this week.
Here's what works for me...
1. Use Alsa 1.0.19. There are other threads on how to upgrade ALSA, but here's something real quick. If my instructions don't work, I suggest finding a method that uses built debian packages and module-assistant. Anything that mentions /usr/local will probably cause you problems later on. I uploaded the alsa source packages to my ppa,
https://launchpad.net/~kachristmas/+archive/ppa, who knows if it will build. If it does, install all the alsa packages, including alsa-source. Then run
Code:
m-a -f --text-mode auto-install alsa-source
2. Reboot.
3. Use
to find the name of the HDMI output. My output looked like
Code:
hdmi:CARD=NVidia
HDA NVidia, NVIDIA HDMI
HDMI Audio Output
null
Discard all samples (playback) or generate zero samples (capture)
4. Again, use output from
to create /etc/asound.conf. My two line /etc/asound.conf looks like this:
Code:
pcm.!default hdmi:NVidia
pcm.iec958 hdmi:NVidia
5. Reboot.
The newer version, 0.9.15, of pulseaudio handles passthrough audio a lot better than the version found in ubuntu 9.04. You can find that in my ppa as well. However, it's probably a good idea to completely disable pulseaudio until you get something working first.