From: Gaspard Bucher <gaspard@...>
Date: 2007-09-25T23:44:11+09:00
Subject: midi scheduler in ruby

I am writing ruby wrappers around rtMidi
(http://www.music.mcgill.ca/~gary/rtmidi/) and need to trigger "note
off".

This is the api I wish to implement:
@midiout = RtMidi.new('port name')
note      = 62
velocity = 100
duration = 0.25  # 1/4
@midiout.play(note, velocity, duration)

When a note is played, a first midi event is created for the velocity,
then, a little later a second for the note off:
[note on ]
[wait    ]
[note off]

1. What is the best way to implement such a scheduler ?

2. Should I create a thread in C that checks for events in a buffer ?

3. Should this scheduler be implemented in Ruby ?
class Scheduler
  def initialize
    @events = []
    Thread.new
      while(true) do
        sleep 0.01 # ?
        if @events[0] && @events[0].time >= Time.now
          @events.shift.trigger
        end
      end
    end
  end

  def <<(e)
    i = 0
    while(@events[i] && e.time <= @events[i])
      i += 1
    end
    if @events[i]
      @events[i..i] << [e, i]
    else
      @events << e
    end
  end
end

Many thanks for your insight.

Gaspard