MIDI input event listener for Ruby

gem install midi-eye

or using Bundler, add this to your Gemfile

gem "midi-eye"

require 'midi-eye'

The following is an example that takes any note messages received from a unimidi input, transposes them up one octave and then sends them to an output

First, pick some MIDI IO ports

@input = UniMIDI::Input.gets
@output = UniMIDI::Output.gets

Then create a listener for the input port

transpose = MIDIEye::Listener.new(@input)

You can bind an event to the listener using Listener#listen_for

The listener will try to positively match the parameters you pass in to the properties of the messages it receives.

In this example, we specify that the listener listens for note on/off messages, which are identifiable by their class.

transpose.listen_for(:class => [MIDIMessage::NoteOn, MIDIMessage::NoteOff]) do |event|

  # raise the note value by an octave
  event[:message].note += 12

  # send the altered note message to the output you chose earlier
  @output.puts(event[:message])

end

There is also the option of leaving out the parameters altogether and including using conditional if/unless/case/etc statements in the callback.

You can bind as many events to a listener as you wish by repeatedly calling Listener#listen_for

Once all the events are bound, start the listener

transpose.run

A listener can also be run in a background thread by passing in :background => true.

transpose.run(:background => true)

transpose.join # join the background thread later

• examples
• rdoc

• Ari Russo <ari.russo at gmail.com>

Apache 2.0, See the file LICENSE

Copyright (c) 2011-2017 Ari Russo