[linux-audio-dev] Re: Modular Jack patch bay

[Dave Robillard]

On Thu, 2004-02-05 at 01:07, Juhana Sadeharju wrote:
> >From: Dave Robillard <drobilla at connect.carleton.ca>
> >
> >Screenshot:
> >http://chat.carleton.ca/~drobilla/patchbay.png
> [ ... ]
> >Eventually it will be a combined jack/alsa patch bay
> 
> How about adding an application menu from which user may
> launch new applications and insert to the patchbay?
> Patchbay would store application's command line parameters.
>
> How about a custom application menu where user has edited the default
> command line parameters? E.g., a Fluidsynth would start with a sample
> file: "fluidsynth-808perc". Of course, applications should support
> configuration and sample loading via command line.

This is what LADCCA is for really.. session management is well out of
the domain of a patch bay, IMO

> How Alsa mixer relates to Patchbay? If I record Alsa's line-in,
> the reverberated output should not be mixed to the recording.
> And other way, if I record reverberation, the original should not
> be recorded. Could there be a Alsa module which has more connections
> than capture1,2 and playback1,2? When I launch Alsamixer, I would
> control levels with it and use Patchbay for routing. Sounds difficult
> if Alsa has only one recording source: "Mix".

That's the beauty of jack.  You have your alsa in, patch it through
jack-rack running a reverb plugin (for example), and record that, or the
raw audio, or both.

> >and if anyone has ideas for an elegant
> >automatic-module-placement solution
> 
> How about manual placement first? User could organize the modules
> and then save the whole thing to file. When user loads the file,
> the display looks the same -- and also all applications are launched.
> If applications are launched from shell or if Patchbay figures out
> the currently running Jack/Alsa system, then automatic placement would
> be needed. But I would like to always build the system from scratch
> or from file with Patchbay.

I do plan on having the ability to save module positions (with LADCCA
sessions), and of course manual placement is there.  But it would still
be nice to have a nice algorithm for automatic placement.  Just being
able to start all your programs paying no attention to your patch bay,
but having it nicely organized when you get to it would be nice.

If course, as someone already said (Steve?) if you loaded up all the
apps you use frequently, positioned them well and saved that, it would
be what you want most of the time (people tend to use the apps they use,
heh).  Of course, only apps that are running would show up.

> Patchbay could recognize all new applications launched from shell.
> Usually one application is launched at a time and manual placement
> is no problem.

Not true really, especially as LADCCA becomes more popular.

> Again, the end result can be saved to file and there
> is no need to redo the placement each time.
> 
> Patchbay files could be inserted to the current patchbay. E.g.,
> a reverb patch could have four reverb related modules which together
> makes the reverb. That is, four different Jack applications.

This doesn't have anything to do with the patch bay, but anyone who
implements a reverb like this should be taken out back and shot
regardless. ;)  This is definately LADSPA-domain.

> Inserted Patchbay files may need null nodes. If multiple modules
> needs the same input, then with the null node the inputs can be
> combined.

Jack allows multiple connections.

You seem to consider the patch bay as much more of a "master"
application than myself.  To me, the ideal patch bay is just there:
facilitates connections apps as nicely as possible, and displays the
current state of connection clearly.

You should definitely look into Jack and LADCCA - alot of your dreams
are already a reality. :)

Thanks for the suggestions..

-Dave