[mythtv-users] alsa rate change on via8237 spdif

Robin Gilks g8ecj at gilks.org
Thu Jun 21 22:02:15 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".
>

Yup - typo - hw:0,1 it is...except its now. For passthru I have to specify
the device as ALSA:iec958:{ AES0 0x02 }. Does that provide any assistance?

> 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".

Ah - there is the first problem of someone using nvidia knowledge - I have
no option to set the IEC958 Playback source in alsamixer. On my nvidia box
I have a Analog to IEC958 Output switch but nowt on the Via box (both
running the same version of alsa 1.0.14rc2).

> 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
> }

Note that I can use the spdif out OK on AC3 recordings in passthrough mode
so I know the hardware works - I just can't address it from a config file
it seems.

Thanks for replying anyway.

-- 
Robin Gilks



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