[PD] pd-0.45 + jack == weirdness

Nick Lanham nick at afternight.org
Wed Jun 26 14:11:15 CEST 2013

On Wed, 26 Jun 2013, yvan volochine wrote:

> On 26/06/13 12:57, Nick Lanham wrote:
>> In my experience, most people using jack these days are aware that most
>> clients will autostart the server if they haven't started it, and it
>> does not confuse them.
> yeah well in my experience you don't need to open a terminal and kill jackd 
> because an app has been too smart and started it for you.

Yeah, that's bad, but that's a bug in the app, not a jack bug.  Jack usually shuts down cleanly if you kill your app.

> I don't know if the following apps use the old jack API but about "starting 
> jack for me when I didn't ask them to":
> * ardour3 does not

- Yes it does.  It will pop up a dialog asking you to configure jack first, but it does start it.

> * audacity does not

- Yep, audacity falls back to alsa if it doesn't see jack

> * any media players that I tried don't..

- You might not have them configured to use jack.  Again, if they call jack_client_open, they will start jack.  Or they detect no jack and fall back.

Also, all the following apps will auto-start jack, and are more similar IMO to PD than audacity or a media player:

* QTractor
* jalv
* calfjackhost
* rosegarden

So, I think it's more common to start it than not to.

> I would expect a call to `jack_client_open()` when I turn DSP on, not when I 
> launch an app with which I might not make audio at all..

Agreed.  If I don't turn on DSP, PD probably shouldn't start jack, but if you haven't started jack and you've configured PD to use jack, and you turn on DSP, it should probably start it.


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