Re: [Jack-Devel] list current (ALSA) device

On Sat, 25 May 2013 20:21:42 +0100 Filipe Lopes <[hidden]>
wrote:
> On Sat, May 25, 2013 at 7:52 PM, Adrian Knoth
> <[hidden]>wrote:
> 
> > On 05/25/2013 11:15 AM, Dan MacDonald wrote:
> >
> > > AFAIK there is no way to discover or display the device currently
> > > used by J1 or J2.
> >
> > In case of ALSA, you can specify the nickname on the command line
> > and know for sure:
> >
> >    jackd -d alsa -d hw:HDSPMxf1cd85
> >
> > Quite clear which device it uses. You get the nicknames from
> > /proc/asound/cards.
> >
> > For firewire devices, the device ID or nickname is part of the
> > portname.
> >
> > For dummy, there is no device, neither for net.
> >
> > IIRC, in case of jackdbus, you can query the backend parameters.
> >
> >
> > After all, JACK is there to abstract from the hardware, some
> > backends don't even have hardware.
> >
> >
> > I don't think a JACK API extension would make sense.
> >
> 
> You're missing the point here.
> 
> After JACK is started, the user is free to change settings - be it
> ~/.jackdrc, qjackctl, jackdbus, etc.
> Once we do that, there's no way to know for sure what device and what
> specific settings the currently running JACK is using.

But jack was invented to abstract this stuff. Once its started, no app
nor the user (who after all started jack;) should care about which
backend and which device is connected.

And even if you modify jack so it tells you that its running with the
backend A and your device B, there are still several possibilities:
 a) some backends (like the firewire backend and also the alsa-backend
 when you sync cards appropriately) aggregate multiple devices
 b) you can always also connect to other alsa-devices with alsa-in/-out
 and fons' alternatives
 c) your backend might be dummy, thus not connecting to any device or
 d) network and thus connecting to one or several computers running
 multiple devices each
 e) and then you can also have network-slaves in your local
 jack-session that also connect to different machine but aren't a
 backend nor device detectable by jack or other apps.

Have fun,

Arnold

1369511140.30633_0.ltw:2,a <20130525214527.344ab6be at xingu dot arnoldarts dot de>