[SOLVED] ALSA- only one program can use sound at a time- no PCM in alsamixer

maples · 05-26-2014, 09:51 PM

Hi!
I recently installed Arch on my laptop. At first there was no sound output, but that was due to the wrong audio card being set as the default. I fixed that with the /etc/asound.conf, and so far it's worked. Today I was messing around with VirtualBox. I usually have music in the background, and Vbox kept giving me an error that the sound device was busy. I noticed that I got a similar error if I tried to start the music player after I started the VM. So at this point, only one program can output to the sound card.

I tried to add something about "dmix" to my ~/.asoundrc according to what the Arch wiki suggested, but after a reboot I can still only have one program output audio.

When I open alsamixer, I noticed that there is no PCM entry. I also noticed that when I change the volume in a program, it directly changes the 'Master' volume.

My laptop is a Dell Inspiron 15r.

Code:

[anthony@newerLaptop ~]$ lspci | grep audio -i
00:03.0 Audio device: Intel Corporation Device 0a0c (rev 09)
00:1b.0 Audio device: Intel Corporation Lynx Point-LP HD Audio Controller (rev 04)

Code:

[anthony@newerLaptop ~]$ cat /etc/asound.conf 
pcm.!default {
	type hw
	card 1
}

ctl.!default {
	type hw
	card 1
}

Code:

[anthony@newerLaptop ~]$ cat .asoundrc 
pcm.dsp {
	type plug
	slave.pcm "dmix"
}

Sorry if I didn't post something I should have, I'm lost at this point!

Thanks for helping!

gengisdave · 05-27-2014, 10:14 AM

I'm not fully experienced in alsa, but I had the same problem as you, resolved with use of "dmixer"; this is my .asoundrc, as you can see it's little different from you; I have just a little problem: phonon (I use it only for amarok) sees an audio card called "alsa", that reset everytime I plug a USB device (my phone, not a pendrive), so I need to close and open amarok to get the "new" audio card.

Code:

pcm.!default {
  type plug
  slave.pcm "dmixer"
}

pcm.dsp0 {
  type plug
  slave.pcm "dmixer"
}

pcm.dmixer {
  type dmix
  ipc_key 1024
  slave {
    pcm hw:2
    #card 2 #front:VSL
    format S32_LE
    rate 48000
  }
}

ignore "format" and "rate", they're needed on my card (PreSonus AudioBox 22VSL), I don't remember why I added pcm.dsp0 but I think it's related to multiple mplayer (it locks dsp device)

Shadow_7 · 05-27-2014, 10:32 AM

The naming convention of PCM doesn't always apply. For some cards it's DAC for digital to analog converter. And ADC for analog to digital converter. Digital being the computer, and Analog being the speakers or microphone. So DAC would be audio OUT and ADC would be audio IN.

Some applications use the OSS layer and you might find more success with launching those applications prefixed with aoss. Although dmix should be a default in most recent incarnations and doesn't need to be explicitly stated in the .asoundrc. YMMV depending on distro and the age of it. Pulseaudio can also be used to better share a soundcard across applications.

You might try using an .asoundrc file with just one line in it.

Code:

defaults.pcm.card 1

maples · 05-27-2014, 12:27 PM

Quote:

Originally Posted by gengisdave

I'm not fully experienced in alsa, but I had the same problem as you, resolved with use of "dmixer"; this is my .asoundrc, as you can see it's little different from you; I have just a little problem: phonon (I use it only for amarok) sees an audio card called "alsa", that reset everytime I plug a USB device (my phone, not a pendrive), so I need to close and open amarok to get the "new" audio card.

Code:

pcm.!default {
  type plug
  slave.pcm "dmixer"
}

pcm.dsp0 {
  type plug
  slave.pcm "dmixer"
}

pcm.dmixer {
  type dmix
  ipc_key 1024
  slave {
    pcm hw:2
    #card 2 #front:VSL
    format S32_LE
    rate 48000
  }
}

ignore "format" and "rate", they're needed on my card (PreSonus AudioBox 22VSL), I don't remember why I added pcm.dsp0 but I think it's related to multiple mplayer (it locks dsp device)

Thanks! This works! The music player (cmus) still directly controls the master volume, but it works now!! Thank you!