[PlanetCCRMA] Question about jack. Possibly a question for Fernando

[Fernando Lopez-Lezcano]

On Sun, 2010-08-15 at 16:40 +0100, William Blackburn wrote:

> Hello everyone.  I have been having some great fun with the low
> latencies using qjackctl, sooperlooper, audacity, a dunlop crybaby
> wah-wah pedal, and a seymour duncan tweakfuzz pedal.  Anyways, my
> question is about jack and more specifically, jackdmp.  I recently
> compiled and installed jackdmp from a subversion link provided on the
> official jack page.  I read that the jackdmp installation 'replaces'
> files in the existing qjackctl

Not exactly, if compiled with the right options it replaces the files in
the existing jack package (if you are using Fedora). Qjackctl is just a
front end gui to jack, is a jack client and would not be changed by a
jack installation. 

> and is made to operate better with multi-core CPUs.  I use an Intel
> Quad Core @ 2.4GHz x 4 so this would be good for me.  Is there a way I
> can make sure that I have installed this properly? 

You could use the jack package from Planet CCRMA (version 1.9.x) unless
you need a bleeding edge svn version. If you install your own from
source you should make sure you install to /usr and not /usr/local,
otherwise you will have _two_ versions of jack installed and that is a
recipe for problems. 

> Fernando.  I think saw that you were on the contributors list as
> making jackdmp compatible with fedora 13.  That's what I put your name
> in the subject.  :) 

Jackdmp has been part of the Planet CCRMA repositories for quite some
time, that is what I have been using. So no, it is not new for fc13 (but
I would have to dig to find exactly when it became the default in Planet
CCRMA). 

> Also, I was wondering if there was a site where people post the
> latencies they are able to achieve using jack.  I think it would be
> interesting to see how people achieve very low-latencies and what
> those latencies are.   

For my concert performances I normally use Jack 1.9.x with 128x2 (two
periods of 128 frames) @ 48KHz. At those settings the system is reliable
- using pci based soundcards. 

-- Fernando