With todays Alsa 1.0.23 release I finally have working HDMI audio on my laptop with the exception of through Pulse Audio. "mplayer video.mkv -ao alsa:device=plughw=1.3" works perfect, but when I set Pulse Audio to output to my hdmi device I get silence with the occasional popping sound. I am running Ubuntu 10.04 Lucid and Pulse Audio is set to internal card profile "off" and hdmi profile is "stereo" with appropriate output checked. Also after that is fixed can I get it so that when I have a hdmi cable connected and video outputted to it that Pulse Audio will automatically switch output from internal to hdmi then back when the cable is disconnected.
