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-   -   ALSA & surround sound *sigh* (https://www.linuxquestions.org/questions/linux-hardware-18/alsa-and-surround-sound-%2Asigh%2A-224429/)

WillemB 08-30-2004 03:19 PM

ALSA & multichannel (aka surround sound)
 
Hello,

I am hoping someone here can help me further. I have spent the last three weeks getting my Terratec DMX X-Fire 1024 soundcard to work properly under Linux Mandrake 10. Although I have learnt a lot (I am a newbie to Linux) I have yet to find the answers I need.

My soundcard is recognised in Linux as the CrystalClear SoundFusion Audio Accelerator and uses the snd-cs46xx driver/module whatever for ALSA and the cs46xx driver for OSS. Although everything works more or less okay in OSS, I am not happy with certain issues that it gives me. ALSA however sounds good... but will only play through my front speakers (and the subwoofer). It is a 4.1 soundcard with a 4.1 system, so that is basically not what I want.

Here's the problem. I am used to getting music (mp3s) and videos played on all 4 speakers (and subwoofer), even if it's just a stereo source. OSS seems to understand this, ALSA does not. It refuses to play through the rear speakers and only plays on the front. It does know I have rear speakers, because "aplay -Drear ~/somesound.wav plays through the rear speakers. In fact, the front and the rear speakers are considered seperate devices: hw0,0 is front and hw0,1 is rear. This is all very nice, I just want the damn thing to play to both simultaneously, without any issues. It seems this is extremely uncommon, eventhough everyone uses a surround soundcard these days: if I can even find some documentation, it is always aimed at turning two soundcards into one, slaving the sound (like the ALSA FAQ). This is NOT what I want (although it works): the sound gets totally out of sync (the front is ahead of the rear etc) and it is just wrong, because it ignores the capabilities that my soundcard has natively:

pcm.ch40dup {
type route
slave.pcm surround40
slave.channels 4
ttable.0.0 1
ttable.1.1 1
ttable.0.2 1
ttable.1.3 1
}

The ALSA FAQ also mentions that I can "combine multiple PCM via the multi plugin first, then use the route plugin over it". It fails to mention what that means, how to do it and all the links leading to more documentation are dead. The ones I did find don't mention it.

Continuing:
aplay -Dsurround40 ~/somesound.wav gives me this error:
aplay: set_params:832: Channels count non available

aplay -Dsurround41 ~/somesound.wav gives me this error:
ALSA lib pcm_hw.c:1055:(snd_pcm_hw_open) open /dev/snd/pcmC0D3p failed: No such file or directory
aplay: main:502: audio open error: No such file or directory

From what I figured out, the surround40 thing should work, because I have /dev/snd/pcmC0D0, 1 & 2.

I would love to hear any suggestions on how to make more of this. It is kind of frustrating to have one of the best soundcards (at the time) to not work properly, once you have made the definitive switch to Linux...

Any help appreciated.

Regards,
Willem.

WillemB 08-31-2004 08:23 AM

*bump*
No one?? Again?

Sorry for bumping, but I have really run out of options to ask for help...


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