For live synth, we have to have the ability to change patches on the fly, in a very reliable and predictable fashion. There are a few projects out there which are striving towards this, but this writer has not (at this writing, 2/12/2013) found any of them bulletproof enough for live stage use. Let’s face it, if we’re live we need to hit a button and know that it will do what we want, period. Some day one or more GUI tools may reach this level, but until then, here is what I am using:
QjackCTL is the venerable, generally default, and most complete single tool for setup, testing, and configuration of the Jack audio system and ALSA MIDI interprocess/hardware patching too. There are newer tools which match possibly all of its functionality, but none its reliability. When building a new OS install, setting up for new hardware, and figuring out what I haven’t got set up right, I use this as primary tool. But like most audio tools for all general-purpose computing platforms, it was not designed for the live stage, it was designed for the studio, so other tools are primary when it’s time to play the music.
aj-snapshot is a command-line and background-service tool which easily manipulates as many different Jack and ALSA MIDI connection sets as desired. It is not GUI at all, so often I create a connection set using QjackCTL and then write it to a file for future use in one of my patches with aj-snapshot. It runs in the background at all times to maintain the current connection set.
Jack is a background process which connects audio and MIDI applications and hardware. It used to be a simple user-level application, run as needed and then turned off when not. Jack2 is a version rebuilt with multicore CPUs in mind, and the DBus version is more recent yet. I have found the DBus version to be very cleanly and smoothly controllable, especially in the script/automation fashion I need for absolutely predictable startup and solid session management. Recent versions of QjackCTL works with this very well, one just has to make sure that the QjackCTL configuration matches script settings.
This PC is dedicated to live synth use. When it boots, it does auto-logon, and runs the below.
#!/bin/bash echo '' echo 'Starting jackd via dBus and configuring...' echo '' jack_control start jack_control ds alsa jack_control dps device hw:NVidia jack_control dps rate 48000 jack_control dps nperiods 2 jack_control dps period 64 jack_control dps midi-driver seq jack_control dps inchannels 2 jack_control dps outchannels 2 jack_control eps realtime true jack_control eps realtime-priority 50 jack_control eps clock-source 1 a2j_control ehw a2j_control start /home/jeb/START-SRO
There are as many of these as there patches in the current rig. They all work like this:
This particular patch, SRO, combines two simultaneous Yoshimi processes, running different configurations stored in the Yoshimi storage area (/home/username/YOSHIMI), using Calf's 12-band EQ for timbre, reverb, and compressor. More about this here.
#!/bin/bash if [ "$(pidof aj-snapshot)" ] then # Remove all jack and alsa connections if running echo "Deleting all connections..." cp /home/jeb/AJNull.xml /home/jeb/AJRunning.xml pkill -1 aj-snapshot else # If aj-snapshot is not running, start and remove all connections echo "Starting aj-snapshot and removing all jack and alsa connections..." cp /home/jeb/AJNull.xml /home/jeb/AJRunning.xml nohup aj-snapshot -dx /home/jeb/AJRunning.xml & fi # If Combine.py is not running, start it if [ ! "$(pidof -x Combine.py)" ] then nohup schedtool -R -p 50 -e /home/jeb/Combine.py > /home/jeb/LOGS/Combine.log & fi # Kill all audio elements killall -9 -w calfjackhost rakarrack yoshimi fluidsynth # Start all relevant processes nohup schedtool -R -p 50 -e calfjackhost --client CalfSRO \ eq12:SRO ! reverb:SRO ! Compressor:SRO > /home/jeb/LOGS/calfjackhost-SRO.log & nohup schedtool -R -p 50 -e yoshimi -N YoshSRO1 -j -l /home/jeb/YOSHIMI/MegaOrgan1.xmz > /home/jeb/LOGS/Yoshimi-SRO1.log & nohup schedtool -R -p 50 -e yoshimi -N YoshSRO2 -j -l /home/jeb/YOSHIMI/MegaOrgan2.xmz > /home/jeb/LOGS/Yoshimi-SRO2.log & sleep 2 # And lastly, create jackd connections for SRO cp /home/jeb/AJSRO.xml /home/jeb/AJRunning.xml pkill -1 aj-snapshot
Solid controllability is always a dire need on the live stage. One simple method is to be to assign function keys to run patch scripts using window manager keymappings. I use LXDE as my window manager for synth, because it places very little burden on the system and yet gives me all the GUI I want to get things done; and happily, LXDE uses a very straightforward XML file for keyboard configuration among other things.
To set a new keystroke to run START-SRO, I do as follows:
<keybind key="C-F12"> <action name="Execute"> <command>/home/username/START-SRO</command> </action> </keybind>
For future reference, mididings reportedly has what is needed to run scripts (and therefore switch patches) when triggered appropriately by both MIDI and OSC.