[LAD] jack client autoconnection

[Bob Ham]

On Mon, 2008-02-04 at 15:14 +0100, Kjetil S. Matheussen wrote:
> On Mon, 4 Feb 2008, Bob Ham wrote:

> > Even less hassle is for clients to do nothing at all and leave the whole
> > business entirely for jackd.  I suggest the following function instead:
> >
> >  int jack_set_autoconnect(jack_client_t *, int autoconnect);
> >
> > This enables a control interface that can present the user with a simple
> > system-wide toggle switch that would dictate whether or not ports are
> > automatically connected.
> >
> 
> I'm not sure what you mean by the last sentence.
> Is the "autoconnect" variable either 0 or 1?

Yes, sorry.  The "int autoconnect" parameter would be a boolean
indicator; 1 to enable autoconnecting, 0 to disable it.  It would
probably be sensible to have a complementary jack_get_autoconnect()
function to return the value as well.

> But how do libjack know the order of ports? By just
> using creation order? Well, I guess that will work.

Indeed.  This is how most client-side autoconnecting seems to work at
the moment.  Clients simply get "a list" of hardware ports from the
server and connect them in sequence against the client's own ports.

> How about this interface then?
> 
> void jack_enable_autoconnect(jack_client_t *);
> void jack_disable_autoconnect(jack_client_t *);
> 
> And then a typical playback client would work like this:
> 
> jack_client_t *client=...
> jack_enable_autoconnect(client);
> jack_port_t *out_port[0]=jack_port_register(client,...);
> jack_port_t *out_port[1]=jack_port_register(client,...);
> jack_disable_autoconnect(client);

Sorry; I obviously wasn't specific enough about the semantics of the
toggle function.

What I am suggesting is not to toggle autoconnecting for individual
clients, but to toggle autoconnecting for *all* clients, globally.  The
flag that gets toggled would be a property of the engine, not the
client.

In terms of autoconnecting, clients would do quite literally nothing at
all.  The above code would be rewritten as follows:

jack_client_t *client=...
jack_port_t *out_port[0]=jack_port_register(client,...);
jack_port_t *out_port[1]=jack_port_register(client,...);

Clients would never call the new function unless they were control
interfaces, eg. QJackCtl, a jack_autoconnect CLI program, or some
gnome-jack-autoconnect-switch applet.

This removes from client authors the burden of implementing
autoconnection, and enables a convenient interface for controlling
autoconnect behaviour.

Bob

-- 
Bob Ham <rah at bash.sh>