fixed problems with destorted sound with pulseaudio on qubes 3.2 -> change request for config file

[ludwig jaffe]

Hi I use qubes 3.2 and sometimes I listend to music using youtube on a
user vm.
Now I had the following problems:
the sound was often distorted, sounded like overdriven pre amplifier,
but if one stops the sound source (youtube in browser, press pause) there was
a trailing 1 second of destorted sound. Like if there was a buffer that was not
served in time and wants to empty out.

So I looked around and found that there is a configuration to be changed:

take a terminal in dom0:

sudo su
(now I am root)
vi /etc/pulse/default.pa

find a section and modify like I did:
### Automatically load driver modules depending on the hardware available
.ifexists module-udev-detect.so
##modified 01.11.17
#load-module module-udev-detect
##against glitches
load-module module-udev-detect tsched=0
##-end-modified 01.11.17

So add tsched=0, this disables PulseAudio's timer-based scheduling
and uses the classic interrupt-driven approach
why? see: http://0pointer.de/blog/projects/pulse-glitch-free.html

now say :wq to your vi
then in your root shell of dom0 say
pkill pulseaudio and it restarts, now without distortion or glitches.

My audio hw is:
Creative Labs EMU20K1 (Soundblaster X-Fi Series)
Having a decent sound board one wants no lowfi destorted sound...

So have fun with better audio.
@qubes-os developer. Maybe, you should patch the file
/etc/pulse/default.pa for dom0 accordingly.

Cheers,

Ludwig