[pulseaudio-discuss] Suggestion for dbus communication with JACK

Lennart Poettering lennart at poettering.net
Sun Oct 25 16:57:39 PDT 2009

On Wed, 21.10.09 06:43, Ng Oon-Ee (ngoonee at gmail.com) wrote:

> On Tue, 2009-10-20 at 16:45 +0200, Lennart Poettering wrote:
> > On Tue, 20.10.09 12:26, Ng Oon-Ee (ngoonee at gmail.com) wrote:
> > 
> > > Quick suggestion, in latest pulse and latest jack pulse will give up
> > > control of the audio hardware when Jack starts (as informed by dbus) and
> > > grab control back once Jack stops. Could module-jack-sink and
> > > module-jack-source also be loaded/unloaded at these points? I took a
> > > quick look/grep through the current git sources but couldn't figure out
> > > where this is handled.
> > 
> > I'd love to add this, and ventilated that a couple of times to the
> > Jack folks already. The last time we discussed that however there was
> > simply no D-Bus name that I could sanely bind this logic to (i.e. a
> > name that is taken as last step of initialization, where we know for
> > sure that Jack is fully accessible) Maybe this has changed, but I
> > believe it hasn't.
> > 
> > It is not an option to bind this logic to the device reservation logic
> > itself because that is supposed to be generic and also doesn't tell us
> > anything about when Jack is fully up and running.
> Ah, looks like it isn't as simple a matter as I'd thought. If I
> understand correctly what you're saying, does this mean that the device
> reservation logic is a general dbus "get your hands off the audio
> device" command to Pulseaudio, currently? That's cool, though making
> what I suggest much more difficult.

Yes exactly. It tells PA to stop using a device. It doesn't tell PA
"hey, now JACK is running and accessible".

> I'm sure the Jack folk know better than I on the D-Bus name, but
> jack_control status seems to work fine to tell me when Jack is ready for
> use, and it communicates via dbus as well...

Last time I checked they had a name there where picking before
actually spawning off the jack audio daemon. As long as things are
that way round this is not useful for PA's needs.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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