I just did a quick test to get the Wolfson audio card from element14
running and ran into some audio issues with the gotham test build - with raspbmc xbmc-release (12.2) audio was fine.
First my setup: rpi connected to PAL CRT TV via composite video (576i50), SPDIF out of Wolfson audio card connected to my DAC.
I copied the Linux kernel+modules from the wolfson NOOBs image to raspbmc, disabled the default /lib/udev/rules.d/30-sound.rules and added a custom udev rule to set the proper alsa mixer settings (this udev rules calls one of the "use-case" scripts from the Wolfson image). BTW: I skipped the /home/pi/.asoundrc shipping with the Wolfson image which ran the default alsa out through the softvol plugin, because it looks like this caused video stutter with xbmc 12.2.
Here's a tarball of the kernel, modules, udev rules and wolfson "use-case" script(s): http://www.horus.com/~hias/tmp/raspbmc-w...140310.tgz
I deleted the guisettings.xml, switched to 20140306b test build and configured audio out to use the wolfson card. After that I noticed I was getting loud static instead of the "click" noise when navigating through the menus.
Playing an audio file or a video file with dvdplayer resulted in the same, loud static noise. Then I noticed that when I turned the volume down to some 10-20% within xbmc audio output was OK - I guess the static must have been digital clipping.
One thing I noticed in the xbmc.log was that xbmc choose the sample format AE_FMT_S24NE4 when playing a 16/44.1 flac. I did some tests with the wolfson image, aplay choose S24LE for a 24/96 wav, mplayer used 32bit float for a MP3 and S16LE for a 16/44.1 flac.
Here's the xbmc.log from playing a 16/44.1 flac: http://www.horus.com/~hias/tmp/xbmc-wolfson-140310.log
I'm not quite sure what exactly is going wrong here - the S24NE4 vs S24LE sample format looks strange, but I have to admit I'm neither really familiar with xbmc/AE nor alsa internals. So I'd really appreciate any hint or what I could check next.
Another thing: when using the default OMXplayer for videos I didn't get any sound at all via the Wolfson card - did I miss something?