[mythtv-users] MythVideo - How can I get digital surround sound....

[Andrew Lyon]

On 6/1/07, Craig Lovold <craig at lovolds.com> wrote:
> I've had my MythTV setup (1 backend, 4 frontend boxes) working
> beautifully in my house for a couple years now but I have been unable to
> get Dolby Digital output.
>
> Two of my frontend boxes have ChainTech AV710 cards and are hooked up to
> Dolby Digital capable preamps, I do not use any analog outputs, strictly
> digital optical connection to the preamp.  For movie playback I use Xine.
>
> Recorded shows and movies playback fine in 2-channel, but if I try
>  to use a passthrough setting and tell Xine to use automatic passthrough
> mode it says that the device is busy.
>
> Why is it so hard to just get an AC3 passthrough to work?
>
> Anybody have a system like this working?
>
>
> Thanks,
>
> Craig L.
>
> >
>
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Ive found that the following settings work very well on several
different systems I've run myth on, without any asoundrc or other
configuration apart from loading the correct alsa modules for whatever
onboard sound is present.

Audio Output Device: ALSA:plug:iec958
Passthru Output Device: ALSA:iec958

Enable AC3 to SPDIF enabled

I am running mythtv-vid 13574.

Some cards seem to need a "reset" to get spdif output working, e.g. my
current gigabyte 965-ds3 with ALC883 will not output spdif unless I
run this first:

amixer set IEC958 mute
aplay -D spdif /usr/share/sounds/alsa/Front_Center.wav
amixer set IEC958 unmute

Andy