[PlanetCCRMA] Jack Problems

Mark Knecht markknecht@attbi.com
Sat Nov 16 21:38:01 2002

I don't actually know what the 'Jack Watchdog Timer' is, but if it is in
anyway hardware based, then this could possibly be a chipset issue also.
Cyrix 686 was sort of a corner case in the PC industry, so there could be
some subtle differences that are either not known or possibly have to be
compiled into the kernel specially.

You could also try subscribing to the Redhat install lists and see if one of
the guys there knows anything about this. They are pretty good about 'odd'

Anything else is way beyond my knowledge of Linux.

Bet of luck,

-----Original Message-----
From: planetccrma-admin@ccrma.Stanford.EDU
[mailto:planetccrma-admin@ccrma.Stanford.EDU]On Behalf Of Fernando Pablo
Sent: Saturday, November 16, 2002 8:23 PM
To: Michael H. Smith
Cc: planetccrma@ccrma.Stanford.EDU
Subject: Re: [PlanetCCRMA] Jack Problems

> >- 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

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