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Re: sound issues

2012/3/2 Darren Crotchett <debian@crotchett.com>
I am having issues with sound on my son's computer.  We are unable to run two sound applications simultaneously.  Occasionally, I can stumble upon a combination of more than one (usually two) that will work together.  But, it's not repeatable.

I have tried a few combinations non of which worked together, such as Skype and Pandora, Pandora and Movie Player (which I guess is Totem), Pandora and VLC.  Oddly, even video would not play on Movie Player while another sound application was open, but VLC video would play (without sound).  I did not try every combination because I just didn't have time.  If you think it would be beneficial, I can go back and do so.  I don't know enough about the backend sound systems that these applications use to interpret which combinations, if any, would be significant in terms of troubleshooting.

Often times, you would not want two sound apps open at the same time.  But, in this case, my son plays Minecraft and talks on Skype.  So, it makes sense in that case.    It seems that whichever one he starts first gets control of the sound output and the other app can't get any output.  

He is using Debian Wheezy AMD64.  He is using Gnome 3 as the desktop.  He is running Pulseaudio.  His motherboard is an Asus P8Z68 Deluxe and proc is i7.  He has a logitech webcam for input.  But, that hasn't been an issue.  I only mention it to explain the USB-Audio below.

I've been using Debian and Linux for many years.  But, I've never been able to wrap my head around sound problems (which I seem to have with every new install).  I get confused by alas, esd, pulseaudio and so on.  Sound issues have always been hit or miss for me, with something sooner or later just ending up working.  I'm not sure how to troubleshoot this.  Any suggestions would be greatly appreciated.

$ cat /proc/asound/cards
 0 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xfae20000 irq 74
 1 [U0x46d0x821    ]: USB-Audio - USB Device 0x46d:0x821
                      USB Device 0x46d:0x821 at usb-0000:00:1d.0-1.4, high speed
 2 [NVidia         ]: HDA-Intel - HDA NVidia
                      HDA NVidia at 0xfa080000 irq 17

Install jackd, qjackctl and vlc-plugin-jack, kill pulseaudio and use alsa.

In VLC preferences->audio choose alsa as output module. Have a look at the device dropdown, there you should see the relevand devices (eg. your intel and hdmi if any).

if you want two or more audio apps to share the same sound device, start qjackctl, tell vlc to use jack output module and do the same with other apps if needed.

In qjackctl connection panel you should see all your alsa compliant apps listed as readable clients and the sound device as writeable clients.

Using skype together with other apps is also possible even if it's a little more tricky, have a look at http://alsa.opensrc.org/Jack_and_Loopback_device_as_Alsa-to-Jack_bridge

I can run skype togeter with other jack/alsa compliant apps, record them and/or route audio output between them using Qjackctl.


L'unica speranza di catarsi, ammesso che ne esista una, resta affidata all'istinto di ribellione, alla rivolta non isterilita in progetti, alla protesta violenta e viscerale.

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