[PlanetCCRMA] Jack Problems

Fernando Pablo Lopez-Lezcano nando@ccrma.Stanford.EDU
Sat Nov 16 20:23:01 2002

> >- try to start it without using real time priority:
> >  jackstart -d alsa -d hw -r 44100
> >
> >- try to start jack as root (I don't why it would make a difference)
> >  su root (and enter the root password)
> >  jackd -d alsa -d hw -r 44100
> >
> >- use the "-v" argument to see more of what is happening:
> >  jackstart -v -R -d alsa -d hw -d 44100
> >
> Starting as root and without real time priority worked.  The soundcard 
> is a Crystal 4235.  It appears that it's working fine now.  What effect 
> will not having real time priority enabled have on other applications?

The effect is that jack is more prone to underruns. Running with real
time priority is a necessity for low latency work. To just try out stuff
and see what happens it is ok if you don't mind the occasional dropout. 

Also, running as root (you need to run both jackd and the client apps as
root) has security implications, but again, if you are on a single user
machine and just testing stuff it is fine. 

I have not idea why it would refuse to run that way:
If I understand correctly both:
  (as root) jackd -R -d alsa -d hw -r 44100
  (as normal user) jackstart -R -d alsa -d hw -r 44100
And both fail with a watchdog timeout?
Maybe you could send a detailed report to the jackit-users mailing list.
-- Fernando