[mythtv-users] Still no AC3 passthrough...

Ryan Steffes rbsteffes at gmail.com
Fri Oct 12 19:50:11 UTC 2007

On 10/12/07, Greg Arena <garena6 at comcast.net> wrote:
>         I posted yesterday with problems getting the AC3
> passthrough to work. I was told that the driver for the SB Audigy
> 4 I had bought didn't support this. So after switching from the
> SB Audigy 4 to a Turtle Beach Riviera card which I was told had
> full support for this, I'm still stuck with the same problem: No
> AC3 passthrough. Audio works fine for 2-channel output through
> the SPDIF optical out for SD and HD broadcasts if I shut off AC3
> passthrough in the setup. But otherwise, I still get silence or
> static when I turn it on.
>         Can somebody out there with a Turtle Beach Riviera (or
> anybody using the snd_cmipci ALSA driver) offer any ideas? Or,
> can you please send me your ALSA config files and tell me how you
> have things set up in the "Audio" section of the front end's
> general setup screen?
>         As I said before, I've gone through all the howto's and
> wiki's I can find, and none has been helpful.
> Thank you,
> Greg

Well, I don't have your particular card, and while I set up the
.asoundrc according to the wiki, it was a bit of a struggle.  However,
that aside, maybe I can still guide you into some responses that
elicit more help from someone more knowledgeable.

Are you using the .asoundrc from the wiki?  If so, have you made sure
the device numbers match up to what your system tells you it should?
My uneducated guess at what's happening is that your non-digital sound
is being sampled correctly for your soundcard, but your digital sound
is being played at the wrong sample rate and needs to be sampled with

What does aplay -l -L report?

Are you using SVN?  Does the version of the mythfrontend you're using
allow for a seperate sound device for AC3 passthrough (I'm not sure
when that went in). Which sound device do you have set for sound?

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