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-   -   Auto connect (via Jack ALSA tab) for Qysynth and Brisol (http://www.linux-archive.org/64-studio-user/386196-auto-connect-via-jack-alsa-tab-qysynth-brisol.html)

Daniel James 06-15-2010 04:29 PM

Auto connect (via Jack ALSA tab) for Qysynth and Brisol
 
Hi Murray,

> I have read your book from Apress - thanks! Well written.

I'm glad you enjoyed it :-)

> I notice when using jack audio server, that sometimes apps like Hydrogen,
> ardour, etc automatically connect in both AUDIO and ALSA tabs in Jack
> connect. On the other hand, Qsynth automatically connect in AUDIO by not
> ALSA tab, and Bristol does not automatically connect in both AUDIO and ALSA
> tab.

These tabs have different functions. The ALSA tab is for MIDI
connections using the built-in MIDI sequencer in the GNU/Linux sound
drivers. Because JACK is now cross-platform, you will also sometimes see
another tab, which is for connections using the new JACK MIDI standard.
Not all applications support JACK MIDI yet.

> Was wondering if you had a resource to point to if there was a way to set
> that up or write a shell script to accomplish that objective...

This will differ according to the individual application. Some apps do
not connect to any audio or MIDI ports unless you explicitly tell them
to. This will either be a setting in the GUI, or a command line
parameter. For those apps which will accept connection parameters on the
command line, it is possible to write a script to cater for your
specific requirements.

For example, here's a little script I wrote to set up ALSA Modular Synth
with a demo patch, stereo JACK outputs and a virtual keyboard. The sleep
commands are needed to prevent the script completing before the
individual applications have had enough time to start properly.

#!/bin/bash
#
echo "Starting ALSA Modular Synth with demo patch..."
exec ams --preset /usr/share/doc/ams/demos/bass_reverb.ams &
sleep 1

echo "Connecting left channel output to Jack..."
exec jack_connect ams_129_0:ams_out_0 system:playback_1 &
sleep 1

echo "Connecting right channel output to Jack..."
exec jack_connect ams_129_0:ams_out_1 system:playback_2 &

echo "Opening virtual MIDI keyboard..."
exec vkeybd &
sleep 2

echo "Connecting virtual MIDI keyboard to Alsa Modular Synth..."
exec aconnect 130:0 129:0

exit 0

This script calls the command line tools jack_connect and aconnect to
make JACK audio and ALSA MIDI connections, respectively.

Cheers!

Daniel
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Pablo Fernandez 06-16-2010 12:36 PM

Auto connect (via Jack ALSA tab) for Qysynth and Brisol
 
This script calls the command line tools jack_connect and aconnect to

make JACK audio and ALSA MIDI connections, respectively.

Also, you may find this writing useful:

http://digitaldub.wordpress.com/2009/12/16/linux-audio-session-scripting/


Cheers! Pablo


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