[pulseaudio-discuss] Problem with USB sound card - clicks and pops on re-open

Christian Iversen chrivers at iversen-net.dk
Sun May 12 08:18:20 PDT 2013

Hi everybody

Here's a problem which I can't solve by googling, but maybe you can help?

I have a USB sound card - Focusrite Scarlett 2i2
   (lsusb dump: http://paste.yt/p2674.html)

It's running with the snd-usb-audio module
   (lsmod dump: http://paste.yt/p2675.html)

I'm running on Kubuntu 13.04, but this has been a problem for a while.

The issue is this:

Every time the sound card is initialized, it goes through a series of 
loud and annoying pops and clicks. They seem fairly regular, and always 
follow roughly the same rhythm: click-pop-pop-pop-pop, occasionally with 
more pops at the end of that.

It seems that this happens because/when the external DAC is powered up.

As long as I play something (like background music), this problem goes away.

I've observed that it seems that pulseaudio releases the audio device 
when it hasn't been used for a while, thus leading to it being re-opened 

I'm experimenting with running "mplayer silence.wav -loop 0" in a 
screen, and this seems to solve the problem, by keeping the audio device 
open all the time.

Is there any way to have pulseaudio keep the device open at all times? 
Or some other way to debug this?

Med venlig hilsen
Christian Iversen

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