[Alsa-user] HDA-Intel SP/DIF AC3 passthrough

[Dobes V. <do...@gm...>]

I'm trying to setup a media center using linux, and I've got the video  =

working OK, and analog stereo output is working OK.  However, I want to =
 =

get the little "digital" light to turn on when I'm playing a DVD.  So fa=
r,  =

I've spent many hours trying to figure this out to no avail.  I'm tempte=
d  =

to update the ALSA wiki page on this topic to say "Don't bother!" but  =

that's just because I'm feeling so frustrated.

# aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC880 Analog [ALC880 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 2: ALC880 Digital [ALC880 Digital]
   Subdevices: 1/1
   Subdevice #0: subdevice #0

# cat /proc/asound/cards
  0 [Intel          ]: HDA-Intel - HDA Intel
                       HDA Intel at 0xfdff8000 irq 169

# find /proc/asound
/proc/asound
/proc/asound/Intel
/proc/asound/card0
/proc/asound/card0/oss_mixer
/proc/asound/card0/id
/proc/asound/card0/codec#2
/proc/asound/card0/pcm2p
/proc/asound/card0/pcm2p/sub0
/proc/asound/card0/pcm2p/sub0/prealloc
/proc/asound/card0/pcm2p/sub0/status
/proc/asound/card0/pcm2p/sub0/sw_params
/proc/asound/card0/pcm2p/sub0/hw_params
/proc/asound/card0/pcm2p/sub0/info
/proc/asound/card0/pcm2p/info
/proc/asound/card0/pcm1c
/proc/asound/card0/pcm1c/oss
/proc/asound/card0/pcm1c/sub1
/proc/asound/card0/pcm1c/sub1/prealloc
/proc/asound/card0/pcm1c/sub1/status
/proc/asound/card0/pcm1c/sub1/sw_params
/proc/asound/card0/pcm1c/sub1/hw_params
/proc/asound/card0/pcm1c/sub1/info
/proc/asound/card0/pcm1c/sub0
/proc/asound/card0/pcm1c/sub0/prealloc
/proc/asound/card0/pcm1c/sub0/status
/proc/asound/card0/pcm1c/sub0/sw_params
/proc/asound/card0/pcm1c/sub0/hw_params
/proc/asound/card0/pcm1c/sub0/info
/proc/asound/card0/pcm1c/info
/proc/asound/card0/pcm0c
/proc/asound/card0/pcm0c/oss
/proc/asound/card0/pcm0c/sub1
/proc/asound/card0/pcm0c/sub1/prealloc
/proc/asound/card0/pcm0c/sub1/status
/proc/asound/card0/pcm0c/sub1/sw_params
/proc/asound/card0/pcm0c/sub1/hw_params
/proc/asound/card0/pcm0c/sub1/info
/proc/asound/card0/pcm0c/sub0
/proc/asound/card0/pcm0c/sub0/prealloc
/proc/asound/card0/pcm0c/sub0/status
/proc/asound/card0/pcm0c/sub0/sw_params
/proc/asound/card0/pcm0c/sub0/hw_params
/proc/asound/card0/pcm0c/sub0/info
/proc/asound/card0/pcm0c/info
/proc/asound/card0/pcm0p
/proc/asound/card0/pcm0p/oss
/proc/asound/card0/pcm0p/sub0
/proc/asound/card0/pcm0p/sub0/prealloc
/proc/asound/card0/pcm0p/sub0/status
/proc/asound/card0/pcm0p/sub0/sw_params
/proc/asound/card0/pcm0p/sub0/hw_params
/proc/asound/card0/pcm0p/sub0/info
/proc/asound/card0/pcm0p/info
/proc/asound/pcm
/proc/asound/timers
/proc/asound/modules
/proc/asound/cards
/proc/asound/devices
/proc/asound/version
/proc/asound/seq
/proc/asound/seq/oss
/proc/asound/seq/timer
/proc/asound/seq/clients
/proc/asound/seq/queues
/proc/asound/seq/drivers
/proc/asound/oss
/proc/asound/oss/sndstat
/proc/asound/oss/devices

# find /dev/snd

/dev/snd
/dev/snd/pcmC0D0c
/dev/snd/pcmC0D0p
/dev/snd/pcmC0D1c
/dev/snd/controlC0
/dev/snd/pcmC0D2p
/dev/snd/seq
/dev/snd/timer

I tried updating my configuration file /etc/alsa/cards/HDA-Intel.conf to=
  =

use device 2 instead of device 1 in the two places where it looked  =

appropriate.  However, I've got no idea if that config file is even bein=
g  =

using for anything.  Am I supposed to copy it on top of my alsa.conf ?  =
 =

I'm quite clueless here.

A typical mplayer command lines I have tried:

mplayer -ac hwac3, -ao alsa:device=3Dspdif VTS_08_4.VOB
mplayer -ac hwac3, -ao alsa:device=3Dhw=3D0.2 VTS_08_4.VOB

In dmesg I see a mildly troubling message: hda_codec:
Unknown model for ALC880, trying auto-probe from BIOS...

I've managed to produce different sounds from the speaker, usually  =

crackling or buzzing, but not what I want to hear.

Can anyone help me?  Or is alsa not quite ready to meet my needs yet?