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Alsa configuration

I'm running the Debian testing distribution on a Shuttle small-form-factor box that is based on the Nvidia Nforce2 chipset.

I finally managed to get my discover configuration set up so that the OSS audio drivers are blacklisted and I can load the snd-intel8x0 ALSA driver successfully. I am still unclear about configuring ALSA however.

I am running the Debian kernel 2.6.7-1-k7 and my speaker system is the Cambridge Soundworks DTS3300 Digital 5.1 surround sound, which is connected through an optical S/PDIF interface.

I have the alsa-base and alsa-utils packages installed. The output from lsmod includes.

Module                  Size  Used by
snd_mixer_oss          19904  0
snd_intel8x0           36140  0
snd_ac97_codec         69572  1 snd_intel8x0
snd_pcm                97508  1 snd_intel8x0
snd_timer              25540  1 snd_pcm
snd_page_alloc         11720  2 snd_intel8x0,snd_pcm
gameport                4736  1 snd_intel8x0
snd_mpu401_uart         8000  1 snd_intel8x0
snd_rawmidi            25408  1 snd_mpu401_uart
snd_seq_device          8264  1 snd_rawmidi
snd 56932 8 snd_mixer_oss,snd_intel8x0,snd_ac97_codec,snd_pcm,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_seq_device
soundcore              10400  1 snd

I am also running devfs and the /dev/snd directory is populated with a large number of devices. The /dev/adspX, /dev/amixerX, etc. devices also show up.

The contents of /proc/asound indicate that the card is being picked up
% cat /proc/asound/cards
0 [nForce2        ]: NFORCE - NVidia nForce2
                     NVidia nForce2 at 0xec081000, irq 20
% cat /proc/asound/pcm
00-00: Intel ICH : NVidia nForce2 : playback 1 : capture 1
00-01: Intel ICH - MIC ADC : NVidia nForce2 - MIC ADC : capture 1
00-02: Intel ICH - IEC958 : NVidia nForce2 - IEC958 : playback 1

I have run both /usr/sbin/alsaconf and alsamixer to ensure that the devices are unmuted.

With XMMS I can select the PCM output device to be hw:0,2 and can play ogg files over the speaker system. However, I have been unable to configure either xine or mplayer to play an AC3 5.1 audio stream for a movie under this configuration.

I see that /usr/share/alsa/cards/NFORCE.conf defines aliases such as surround51 but I'm not sure that this is ever being sourced. At least I don't see such devices when configuring sound applications.

In the file /usr/share/doc/alsa-base/README.Debian there is a suggestion

2) A configuration example for version 0.9/1.0 of ALSA is in
   /usr/share/doc/alsa-base/examples/modules-1.0.conf, which should be
   installed into /etc/alsa/modutils/1.0.

but I don't have a directory /usr/share/doc/alsa-base/examples/ and it is not installed by the package

ii  alsa-base      1.0.5a-1       ALSA sound driver common files

I would appreciate suggestions.  Please cc: me on replies.

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