[Alsa-user] ICH5 + spdif out

[<ya...@he...>]

Greetings,

I've seen others having similar problems, but my findings are quite
astounding (at least for me), so I've decided to write here anyway.

I've had Abit IS7 motherboard, which introduces ICH5 audio chip. It
works with Alsa using intel8x0 driver and ac97_codec. Having all
"normal" stuff working fine, I've decided it's time to hook up my old
MD, as IS7 introduces optical spdif outlet. I've made the connections,
pressed REC on MD, and...

... after few hours found what follows:

I've got digital signal when:

* both 'IEC958' and 'IEC958 Playback AC97-SPSA' are unmuted
* recording is toggled on 'Capture' (what in the hell's name is that? :)
* 'Analog to IEC958 Output' is unmuted
* I play through 'spdif' pcm

OR

* following http://sourceforge.net/mailarchive/message.php?msg_id=8435450 
  I modify my .asoundrc
* I MUTE 'Analog to IEC958 Output'
* I play through 'r8' pcm.

Having two ways to get digital output, you'd say that I must be happy?
Well, I'm more curious than happy, because I can't see the logic behind
all of this:

In first case:
* why 'Capture' must be toggled on?
* why must I play through 'spdif', when 'Analog to IEC958' is on?

In second case:
* how does it work?
* why must I turn 'Analog to IEC958' *OFF*?

My goal is in fact really simple - to "clone" normal output to spdif as
well. Sometimes I'd like to record sound from non-alsa app, that cannot
be tricked to play through specific pcm. As far as logic applies, case
no 1 should work even without playing through spdif. But it does not :(

Lastly, some information on my system:

+yacoob:/proc/asound[233]> cat /proc/asound/version
Advanced Linux Sound Architecture Driver Version 1.0.4 (Mon May 17
14:31:44 2004 UTC).
Compiled on Sep  2 2004 for kernel 2.6.8minolta.


yacoob:/proc/asound[232]> cat cards
0 [ICH5           ]: ICH - Intel ICH5
                     Intel ICH5 at 0xfc001000, irq 17

+yacoob:/proc/asound[237]> cat devices
  1:       : sequencer
  0: [0- 0]: ctl
 20: [0- 4]: digital audio playback
 27: [0- 3]: digital audio capture
 26: [0- 2]: digital audio capture
 25: [0- 1]: digital audio capture
 16: [0- 0]: digital audio playback
 24: [0- 0]: digital audio capture
 33:       : timer

Just to be precise, playing through hw:0,4 does nothing. That is, no output, no
error msgs, nothing. Oh, and xmms slider does not advance as normal.

I can say that I've got it working, but honestly, I'd appreciate some
explanations about inner workings of it. Perhaps there's some bug? And to be
honest, if sheer digital output took me this long to enable, I wouldn't think
about experimenting with dmix or "normal" 5.1 output... O_o

I'd be grateful for *any* information.

KT.