Digital Audio out!

Finally, I have digital audio out working on the Shuttle. The SPDIF output is hooked up to my Yamaha amp which is now cheerfully decoding Dolby Digital and PCM data.

This required a recent version of the kernel ALSA drivers (it first worked with 1.0.9b but I'm now using 1.0.10 which appears to be more stable) and I had to use the following atiixp module option in /etc/modprobe.conf:

# try the direct approach...
options snd_atiixp spdif_aclink=0

I needed to add this to ~mythtv/.asoundrc:

pcm.!default {
     type plug
     slave {
          pcm "spdif"
          rate 48000
          format S16_LE
     }
}

and set the sound device to ALSA:default in the local frontend MythTV configuration in order to get non-48KHz PCM data (eg. from mythmusic) to be re-sampled and sent out as a digital stream.

To get this working with DVDs (video output using Xv on the PVR350), I used mplayer with these flags:

mplayer -geometry 720x576+0+0 -noaspect dvd:// -ao alsa:noblock -vo xv -afm hwac3 -alang en

I also made it work with xine after editing the config to allow AC3 pass-through.