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

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Subject: [linux-audio-dev] Re: Modular Jack patch bay
From: Juhana Sadeharju (kouhia_AT_nic.funet.fi)
Date: Thu Feb 05 2004 - 08:07:43 EET


>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.

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".

>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.

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

Inserted Patchbay files may need null nodes. If multiple modules
needs the same input, then with the null node the inputs can be
combined. There is no Jack application for the null node.
User who inserts the reverb to the patchbay then don't have to guess
how to connect the inputs to the reverb related modules -- their
inputs would not be connected at all without the null node.
A subpatches/macros would make the same thing, but would be more
complicated.

Should users be able to set the launching order of applications
in the patchbay files?

Regards,
Juhana


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