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Re: /usr/bin/qjackctl and pasuspender on Wheezy

On 05/29/2012 08:19 PM, Felipe Sateler wrote:

I'm not an expert in JACK, so hopefully someone will correct me if I'm wrong...

On Tue, May 29, 2012 at 12:52 PM, Kaj Ailomaa<ailomaa@warpmail.net>  wrote:


Not being a scripting wizard, I'm not able to understand how
/usr/bin/qjackctl works.

Is PA supposed to be suspended at some point?


Only if you have jackd2 with dbus support (like the jackd2 package in debian).


I can't figure out if it is because of /usr/bin/qjackctl at any point.


AFAIK, no. It is the jack daemon that negotiates the sound card with
PA, qjackctl just starts and stops it. This information is all based
on last time I tried automatic negotiation, which was a while ago.
If PA is already using the sound card (say, your mp3 player is
running), the negotiation will fail and PA will not let jackd have
control of the sound card. In other words, jack asks "pretty please,
can I have the sound card?", and PA decides wether to do it or not.



There is some pasuspender stuff in the /usr/bin/qjackctl starter script.
In the past, starting qjackctl suspended PA. Now it doesn't. What does the pasuspender stuff in the script do for us now?
I talked with someone who had a problem suspending PA by starting jackdbus from qjackctl, after having removed pulseaudio-module-jack. For me, this is not the case, so perhaps he provided me with wrong information. Qjackctl, with or without dbus enabled, will suspend PA when I have set jack to use the same output as PA is using. 




I realize, if wanting to use pulseaudio-module-jack, you don't want PA to
get suspended. But what if you uninstall it, or disable d-bus in qjackctl
(in effect starting jackd instead of jackdmp)?


I've never installed pulseaudio-module-jack, but from what I
understand it is not very useful, since pulseaudio is much higher
latency than jack.
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