[mythtv-users] SPDIF digital volume control - Do I have it right?

ozizaeb at comcast.net ozizaeb at comcast.net
Mon Jan 2 05:32:11 UTC 2006

I struggled for many days with lots of searches on various sites for this 
solution.  I had my ALSA config per the DigitalSoundHowTo but wanted to be 
able to control the volume of mixed-digital output with my Happauge PVR-250 
remote.  I came across some entries about the "softvol" ALSA plugin.  After 
playing around with it I was able to get the PCM volume control to control my 
SPDIF digital output jack volume with the following /etc/asound.conf 

# Control device (mixer, etc.) for the card
pcm.mixed-digital {
 type plug
 slave.pcm "spdifvol" # <- This used to be "dmix-digital" per 
DigitalSoundHowTo.  Now points to the spdifvol definition.

# Added this entire section which filters the dmix-digital with the "PCM" 
control.  My SPDIF jack is device 1 of my ATI IXP 150 PCI audio controller.
pcm.spdifvol {
 type softvol
 slave.pcm "dmix-digital"
 control {
   name "PCM"
   card 0
   device 1

Since I'm not by FAR from an ALSA expert I'm not exactly sure this the 
"correct" way of using softvol.  Maybe someone with more experience can 
correct it or tell me why it doesn't exactly work.  It seems to work for me 
but I could be missing something.  If it is correct, it would be a nice thing 
to add to the DigitalSoundHowTo.

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