Randomise midi events in garageband?

Question

Hi. Anyone know of a plugin or method to randomise midi events in garageband? E.g. I'd like to be able to randomise (to a controlled degree) note velocities (preferably within a specified range perhaps ± one or two points) and note beginnings (± a few miliseconds). It's a big project I'm working on so it'd be nice if there were a plugin or some other automated means of accomplishing this.
Thank you in advance,
Niall, Dublin, Ireland

Answer 1

I'm trying to do a similar thing - I'm no expert but here's a few ideas:
First you need a Transmitter not a Receiver (confusingly) - it takes signals from your keyboard and Transmits them to other receivers in your program.
So you have a Device, d, a Transmitter, t, and use MidiSystem.getSequencer() to get a Sequencer, s.
You also need a Receiver for the sequencer, r.
add the Transmitter to the Device: t = d.getTransmitter();
add the Receiver to the Sequencer r = s.getReceiver();
connect them together: t.setReceiver(r);
The class where you want to do stuff with incoming midi signals should implement interface ControllerEventListener, i.e. it has a method controlChange(shortMessage event) which will be called when the sequencer receives midi via receiver r. Then, provided the above code is inside this class, you can add the event listener to the sequencer by:
listenedSoFar = s.addControllerEventListener(this, listened)
where listened is int[], a list of the kinds of messages you want to deal with. Elements can be between 0-127. Class ShortMessage has constatnts for these like ShortMessage.NOTE_ON etc. listenedSoFar is a list of all the kinds of messages this event listener responds to. If this is the first/only addControllerEventListener then listenedSoFar should equal listened.
I'm not sure this is exactly right as i'm in the middle of writing my program. If you've already cracked the problem then any tips you have would be appreciated.
George