I'm trying to use the optical output of my Shuttle SN41G (AMD) it has a VIA soundcard built on the motherboard and a optical output on the front of the machine which I want to use for 5.1 (6.1/7.1 if supported) sound to my amplifier.


I've tried ALSA:spdif ALSA:default ALSA:digital

Alternated with ac3 passthrough and other settings below that with no luck at all.


lspci says it's:


and the output of aplay -l:



Any help would be appreciated.

So far I have no sound from anywhere and I've used alsamixer to unmute everything.[/code]

Do you have anything defined in /etc/asound.conf that mirrors the options you tried?

If you tell MythTV to use ALSA:foo, it means there must be a "foo" pcm defined for that card, either as "pcm.foo" or "pcm.!foo" depending on whether or not it overrides a default setting.

asound.conf files are very driver- and hardware-dependent. Your first check should be to go to the ALSA website for your particular soundcard and look in the comments for the driver. See if anyone has posted an asound.conf (or .asoundrc - it's the same file type at the user level vs. the system level) for your card.

Your second check would be to google for things like "[your chipset] optical S/PDIF alsa" and "[your chipset] optical SPDIF alsa" (It's technically S/PDIF - Sony/Philips Digital Interconnect Format, but often people say SPDIF. You usually have to search on both.)

You'll want to choose AC3 passthrough in MythTV, though. That I can tell you for certain.

Once you can play any audio (or video with audio) like this:

mplayer -ao alsa:device=[your chosen device] -ac hwac3,

then you know everything's configured right on the system. Then you can work on tweaking MythTV settings.

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I had unmuted IEC958 Analog and that screwed things up..

Muting it made the sound work.

It may be worth adding this hint to the HowTo on the Wiki if it isn't already there...