MIDI Message

MIDI messages, objectified in Ruby

Features

• Flexible API to accommodate various sources and destinations of MIDI data

• Simple OO approach to System Exclusive data and devices

• YAML dictionary of MIDI constants

Install

gem install midi-message

Usage

require 'midi-message'

include MIDIMessage

Basic Messages

There are a few ways to create a new MIDI message. Here are some examples

NoteOn.new(0, 64, 64)

NoteOn["E4"].new(0, 100)

with(:channel => 0, :velocity => 100) { |context| context.note_on("E4") }

Those expressions all evaluate to the same object

#<MIDIMessage::NoteOn:0x9c1c240
 @channel=0,
 @data=[64, 64],
 @name="E4",
 @note=64,
 @status=[9, 0],
 @velocity=64,
 @verbose_name="Note On: E4">

SysEx Messages

As with any kind of message, you can begin with raw data

SystemExclusive.new(0xF0, 0x41, 0x10, 0x42, 0x12, 0x40, 0x00, 0x7F, 0x00, 0x41, 0xF7)

Or in a more object oriented way

synth = SystemExclusive::Node.new(0x41, 0x42, :device_id => 0x10)

SystemExclusive::Command.new([0x40, 0x7F, 0x00], 0x00, :node => synth)

A Node represents a device that you’re sending a message to (eg. your Yamaha DX7 is a Node). Sysex messages can either be a Command or Request

You can use the Node to instantiate a message

synth.command([0x40, 0x7F, 0x00], 0x00)

One way or another, you will wind up with a pair of objects like this

#<MIDIMessage::SystemExclusive::Command:0x9c1e57c
@address=[64, 0, 127],
@checksum=[65],
@data=[0],
@node=
 #<MIDIMessage::SystemExclusive::Node:0x9c1e5a4
  @device_id=16,
  @manufacturer=65,
  @model_id=66>>

Parsing

The parse method will take any valid message data and return the object representation

MIDIMessage.parse(0x90, 0x40, 0x40)

  #<MIDIMessage::NoteOn:0x9c1c240 ..>

MIDIMessage.parse(0xF0, 0x41, 0x10, 0x42, 0x12, 0x40, 0x00, 0x7F, 0x00, 0x41, 0xF7)

  #<MIDIMessage::SystemExclusive::Command:0x9c1e57c ..>

Check out nibbler for more advanced parsing

API Documentation

• rdoc

Author

• Ari Russo <ari.russo at gmail.com>

License

Apache 2.0, See the file LICENSE

Copyright © 2011 Ari Russo