[LAU] sound card "sync/distortion"

Atte André Jensen atte.jensen at gmail.com
Wed Mar 18 05:57:57 EDT 2009

MarcO'Chapeau wrote:

> - Which Jack version ?

atte at vestbjerg:~/music/chuck/modlys$ jackd -V
jackd version 0.109.2 tmpdir /dev/shm protocol 22

Note that the problem is also there when running straight to alsa. 
Sometimes I would actually preffer that, for instance with chuck. But 
using alsa leaves me without control over the problem. Since (as stated 
below) the problem is *never* there on the first run of chuck after 
restarting jack through qjackctl, my solution with chuck is to start 
qjackctl in the beginning of my chuck-loading bash script and killall it 
at the end. Since I'm using chuck live I have to do this dance, as it's 
naturally totally unacceptable to have the problem, however rarely, in 
front of an audience.

> - can you record the distortion ?

Yes, I put them here:

They are all recorded with my edirol r09, simply recording what's coming 
out of my speakers, so the sound quality is not that great. All files 
are the same tune.

The first two are with chuck (first one without the problem, second with 
the distortion problem), the last two are with energyXT (again first one 
without the problem, second with the distortion problem).

Comparing the two clients, chuck and energyXT:

Chuck seems to be really bad at this, almost no matter what I do. Larger 
projects (more to load, heavy cpu load) makes is more often. Restarting 
jack from qjackctl *always* makes the problem go away the first time I 
start chuck, but consecutive runs of chuck start to be infected.

EnergyXT almost never does this on light cpu loads. When the cpu load of 
a project get's heavier loading that particular project increases the 
chance of getting the problem. It seems that if the problem has once 
been caused by energyXT, it will stay distorted (even if 
closing/restarting energyXT also with a lighter project) until I restart 

> - Do you get Xruns, or does it just sound weird ?

No xruns.


http://atte.dk    http://modlys.dk

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