[LAD] Document on using Jack Apps

Arvind Venkatasubramanian mdu.arvind at gmail.com
Mon Aug 2 02:46:59 UTC 2010


On Sun, Aug 1, 2010 at 2:53 PM, Rui Nuno Capela <rncbc at rncbc.org> wrote:

> On 08/01/2010 07:37 PM, Arvind Venkatasubramanian wrote:
> >
> > *Question on using QJACKctl:*
> >
> > I was able to create some basic setting, load and read latency that gets
> > printed on the terminal.  But what do the parameters on the setting tab
> > of console pop up mean?  No soft mode, monitor, priority, time out etc
> > and the options tab.  How do I use these options and tine tune them in
> > order to set the minimum feasible latency for the application that I
> > intend to develop?  Above all, if the drop down menu options does not
> > allow me to choose lower sampling rates, what command do I use on the
> > CLI to do the setting.  Or Do I need to edit QJACKctl's .conf file to
> > set lower sampling rates manually.
> >
>
> all options on the qjackctl setup settings dialog are mapped in a
> one-to-one basis to jackd command line options. they are just presented
> in a bland gui dialog for convenience.
>
> cheers
> --
> rncbc aka Rui Nuno Capela
>




*To measure sound card latency by patching JDelay in qJackctl:*

*Irrespective* of changing different parameters combinations, I get the
following printed out in the terminal:

Signal below threshold...
Signal below threshold...
Signal below threshold...
  2072.829 frames     43.184 ms Inv
  2072.866 frames     43.185 ms Inv
  2072.846 frames     43.184 ms Inv
  2072.838 frames     43.184 ms Inv
  2072.855 frames     43.184 ms Inv
  2072.840 frames     43.184 ms Inv
  2072.842 frames     43.184 ms Inv
  2072.853 frames     43.184 ms Inv
  2072.835 frames     43.184 ms Inv
  2072.848 frames     43.184 ms Inv

The program does not seem to recognize the changes I made in the GUI
parameters settings.

How I did it:

   1. I connected my sound card out to sound card in.
   2. Then patched my JackDelay In to system caputre 1.
   3. I patched playback 1 to JackDelay out.

Regards,
Arvind V
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