[mythtv-users] alsa rate change on via8237 spdif

Michael T. Dean mtdean at thirdcontact.com
Thu Jun 21 14:13:34 UTC 2007


On 06/21/2007 12:59 AM, Robin Gilks wrote:
> I've been playing with asoundrc file on and off for 2 years trying to sort
> this out.
>   
...
> The problem is that all the examples I've seen quote nvidia sound chips
> which allow the spdif port to be addressed as device 1:0 but I can't do
>   

Don't know if it's a typo here, or if you also have it wrong in your
device names, but that's actually "hw:0,1" (the separators are dependent
on the app, but the important part is that it should be card 0, device
1).  For example, MPlayer uses the ugly string "alsa:device=hw=0.1". 
Myth uses "ALSA:hw:0,1".

> that on my Epia SP13000. The output of 'aplay -l' gives:
>
> **** List of PLAYBACK Hardware Devices ****
> card 0: V8237 [VIA 8237], device 0: VIA 8237 [VIA 8237]
>   Subdevices: 4/4
>   Subdevice #0: subdevice #0
>   Subdevice #1: subdevice #1
>   Subdevice #2: subdevice #2
>   Subdevice #3: subdevice #3
> card 0: V8237 [VIA 8237], device 1: VIA 8237 [VIA 8237]
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
>
> Note that device 1 has no extra name whereas the soundcard on my other box
> (which is an nvidia as it happens) gives:
>
> **** List of PLAYBACK Hardware Devices ****
> card 0: nForce2 [NVidia nForce2], device 0: Intel ICH [NVidia nForce2]
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
> card 0: nForce2 [NVidia nForce2], device 2: Intel ICH - IEC958 [NVidia
> nForce2 - IEC958]
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
>
> which indicates that the device 1:0 is the IEC958 port.
>   

So, for yours, it's hw:0,1...

> I've tried using the converter plugin (with samplerate_best) but since I
> can't get a handle on the device I can't hook it!! I don't get an error
> message when I try to use device 1:0 - it just doesn't work!!

Because you probably don't have a soundcard 1... :)

Anyway, IEC958 unmuted, IEC958 Playback AC97-SPSA on 0 ("volume off" in
alsamixer), IEC958 Playback Source on PCM.  And (here's the part you're
not expecting), use the ALSA device hw:0,0.  I.e. set up Myth with
"ALSA:hw:0,0".

Once you set the ALSA IEC958 settings, you can simply use the asoundrc
on the wiki with analog-hw /and/ digital-hw both set to:

pcm.<analog or digital>-hw {
  type hw
  card 0
  # The default value for device is 0, so no need to specify
  device 0
}

Mike


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