[mythtv-users] Via VT8233 and SPDIF TOSLINK output

[Shawn Willden]

Robert Tsai wrote:

>I had the same symptoms.
>
>Have you first tried the normal analog audio ports to make sound is
>working at all? If the analog audio isn't working, then maybe you have
>a deeper problem. (I encountered a Dell motherboard where the normal
>audio port in Linux was actually the *surround* port in Windows.)
>  
>

Yes, analog sound works fine.  I had to plug some headphones into the 
speaker jack to test it, because I don't have anything to convert from 
the 1/8" stereo plug to the RCA plugs I'd need to plug it into my 
receiver, but that was one of the first things I tried.

>Assuming that that much is working, try the following two commands in
>sequence:
>
>	amixer set 'IEC958 Playback AC97-SPSA' 3
>	amixer set 'IEC958 Playback AC97-SPSA' 0
>
>The last one (setting to "0") is the important one, which you've
>alluded to. It's supposed to be idempotent (e.g., just establishing
>some configuration), but I consistently have to *change* the value to
>zero to get SPDIF audio working properly, so I've just placed these
>two commands into my myth user's .login
>  
>

No luck, unfortunately.  I get the same behavior after doing that.  I do 
notice something interesting about the output, though.  Running the 
first command gives me:

---
Simple mixer control 'IEC958 Playback AC97-SPSA' 0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Limits: 0 - 3
  Mono: 3 [100%]
---

Is the "Playback channels: Mono" normal?

>I haven't used aplay because I don't have any WAV files; I was using
>mpg321 with some mp3s as my test program for playing music.
>  
>

I've just been using /usr/share/sounds/beg.wav.  I'll bet you have a 
bunch of little wav files you could try, too.  Using mpg321's "-a" 
option would work if I knew which device the SPDIF output is.

>Anyway, you've already mentioned that you've fiddled with the above
>alsamixer settings, so maybe you have something else going wrong, but
>the above two amixer commands do the trick for me.
>
>FWIW, I have a Soltek SL-K8TPro-939 motherboard (same VIA VT8233 audio
>chip).
>  
>

Yeah, it seems to be pretty common.  My desktop machine has one, too.  
It actually has a TOSLINK output also... maybe I should try hooking that 
box up to my receiver, just for kicks...

Thanks,

    Shawn.