[mythtv-users] Alsa SPDIF SP13000 (via8237)

[Robin Gilks]

> Because you need a valid ALSA configuration that allows for conversion
> of the sample rate, channels, and format to those required by your
> card.  I.e. you need to use the .asoundrc/asound.conf from the wiki (
> http://www.mythtv.org/wiki/index.php/DigitalSoundHowTo#Setting_up_ALSA.27s_.asoundrc.2C_Properly
> ) configured with:

Already done that


> # Alias for digital (S/PDIF) output on the card
> # Do not use this directly--it requires specific rate, channels, and
> format
> pcm.digital-hw {
>   type hw
>   card 0
>   device 0
>   subdevice 3
> }

Already done that

>
> BTW, aplay -D hw:0,0,3 would likely fail even with AC-3/DTS passthrough
> because it doesn't properly configure the device.  Therefore, the ALSA
> devs created a built-in device name iec958 to do the required device
> configuration.  Since normal people don't care (don't remember) that an
> S/PDIF output is an IEC958 device, they also created a built-in alias
> called spdif to make it easy to access.

This makes it difficult to test. If I can't get aplay -D hw:0,0,3 to work,
how do I know if I have the correct device/subdevice. I've tried using
aplay -D mixed-digital ... anyway. No joy :-(

Can you suggest a workaround for the  pcm.digital-hw section of the
asound.conf file - is it valid to reference the IEC958 device directly
instead of as 0,0,3 (since that obviously doesn't work for me)? If so, how
is it referenced?


>
> This lack of configuration is also the reason that the wiki ALSA config
> files will not work with AC-3/DTS (on all systems).  One of these days,
> I'll fix it.  (Maybe in September.)

I'm sure its a simple fix but without knowing the design criteria for alsa
and the manner in which the config file is parsed to map to built-in
devices.

As an aside, what is the "iec958:AES0=0x6,AES1=0x81,AES2=0x0,AES3=0x2"
that xine decides is its passthrough device?

-- 
Robin Gilks