[LAU] Crackles in audio - how to troubleshoot ?

jonetsu at teksavvy.com jonetsu at teksavvy.com
Sat Aug 27 01:46:31 UTC 2016

On Thu, 25 Aug 2016 15:20:40 -0400
"jonetsu at teksavvy.com" <jonetsu at teksavvy.com> wrote:

> Suddenly the audio started crackling.  

Update.  I was listening for about an hour to youtube videos,
interviews eg. talks, using firefox and the audio was fine.  Previous
to that I listened for about an hour to tutorials using vlc and mp4
files, and used Mixbus 32C (ardour) to test some recording using the new
pre-amp. All in all, at least two hours with correct audio.

Then I started Bitwig, loaded a project and played the tracks.
Immediate crackle.  Within one minute I terminated Bitwig, started
firefox, went to a youtube video featuring only talks (so it is cleaner
to hear what's going on) and there was crackle in the audio.

As this shows so far, Bitwig contaminated the audio system.  Or it is a
coincidence ? I will see in the coming days.

Now, _if_ the problem is purely software based, no capacitors involved,
is there a way, short of a reboot, to reinitialize completely the audio
infrastructure ?  Like cleaning up every buffer, everything and
restart the audio subsystem as if a reboot has happened ?

What runs on this system is:

S<Ll  /usr/bin/pulseaudio --start --log-target=syslog

Z<    [pulseaudio] <defunct>

S<Lsl /usr/bin/jackd -T -ndefault --sync -T -P95 -ndefault -dalsa
      -dhw:M1010LT -r44100 -p128 -n2

S     /usr/lib/pulseaudio/pulse/gconf-helper

Yes, there is always a zombie pulseaudio process.  Killing -9 pulseaudio
is not easy, if possible at all, since it will always restart.

Is it possible to reinitialize the audio subsystem without rebooting ?
Not only this will be a faster work around, but it will also make
testing much easier.


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