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Full Version: [LINUX] Ubuntu 9.10 Karmic and AC3 Passthru / Surround Sound
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I had a bugger of a conundrum last night with my freshly upgraded Ubuntu to 9.10 Karmic Koala. Everything was working wonderfully (especially the full support built-in for my iMon Pad remote)... except that I couldn't get any surround sound to work.

I was previously using my onboard optical output with IEC958 to do AC3 Passthru on loads of movies. All of my settings looked correct, but still, it was a no-go.

Did some research and discovered that Pulseaudio (default in 9.10) doesn't support any form of AC3 passthru/surround/5.1/what-have-you.

I tried a lot of manual settings to have XBMC fallback and use ALSA instead of even trying to hook into Pulse, but apparently Pulse is too hard-wired throughout the system to just override it like that.

The Solution
Remove pulseaudio. (Seriously, just use ALSA instead)
Code:
sudo apt-get purge pulseaudio

Done. Smile
Yes it's true it's worked but after removing pulseaudio almost all other ubuntu application doesn't have sound anymore so make a choice or AC3 sound in XBMC or sound in ubuntu
Well, considering this is a dedicated XBMC machine, removing it was the easiest option!
When I used mythtv under Karmic I used to use Mplayer to play my movies. My custom mplayer command looked something like 'pasuspender mplayer dvd:// -ao alsa -ac hwac3, etc'

The pasuspender command would force PA to let go of the sound card allowing me to use passthrough with Alsa.

I don't know how XBMC does it in Karmic but I have sound AND full passthrough on DD movies just by setting the standard sound options (output = digital, dolby rec = true, device = default, passthrough = iec958)

I also have modifed PA's config to route all sounds to Alsa's HW digital out (for 'normal' sounds i.e non passthrough which like you say is not possible in PA)

I don't know if XBMC is suspending PA completely like MythTV frontend now does when it starts (can other normal pulse apps play sound with xbmc running?) or just when it wants to use passthrough with Alsa.