MIDI Events

Ruby MIDI Events Objects

This library is part of a suite of Ruby libraries for MIDI:

This library is based on Ari Russo's library MIDI Message.

• Flexible API to accommodate various sources and destinations of MIDI data
• Simple approach to System Exclusive data and devices
• YAML dictionary of MIDI constants

gem install midi-events

Or if you're using Bundler, add this to your Gemfile

gem "midi-events"

require "midi-events"

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

MIDIEvents::NoteOn.new(0, 64, 64)

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

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

Those expressions all evaluate to the same object:

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

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

MIDIEvents::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, model_id: 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:

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

• (TO DO) rdoc

MIDI Events is mostly a clone of MIDI Message with some modifications:

• Renamed gem to midi-events instead of midi-message
• Renamed module to MIDIEvents instead of MIDIMessage
• Removed parsing features (in favour of the more complete parser MIDI Parser)
• TODO: update tests to use rspec instead of rake
• TODO: migrate to (or confirm it's working ok on) Ruby 3.0 and Ruby 3.1

The author has been developing since 2016 a Ruby project called Musa DSL that needs a way of representing MIDI Events and a way of communicating with MIDI Instruments and MIDI Control Surfaces.

Ari Russo has done a great job creating several interdependent Ruby libraries that allow MIDI Events representation (MIDI Message and Nibbler) and communication with MIDI Instruments and MIDI Control Surfaces (unimidi, ffi-coremidi and others) that, with some modifications, I've been using in MusaDSL.

After thinking about the best approach to publish MusaDSL I've decided to publish my own renamed version of the modified dependencies because:

• The original libraries have features (buffering, very detailed logging and processing history information, not locking behaviour when waiting input midi messages) that are not needed in MusaDSL and, in fact, can degrade the performance on some use cases in MusaDSL.
• The requirements for Musa DSL users probably will evolve in time, so it will be easier to maintain an independent source code base.
• Some differences on the approach of the modifications vs the original library doesn't allow to merge the modifications on the original libraries.
• Then the renaming of the libraries is needed to avoid confusing existent users of the original libraries.
• Due to some of the interdependencies of Ari Russo libraries, the modification and renaming on some of the low level libraries (ffi-coremidi, etc.) forces to modify and rename unimidi library.

All in all I have decided to publish a suite of libraries optimized for MusaDSL use case that also can be used by other people in their projects.

• Javier Sánchez Yeste

Thanks to Ari Russo for his ruby library MIDI Message licensed as Apache License 2.0.

MIDI Events Copyright (c) 2021 Javier Sánchez Yeste, licensed under LGPL 3.0 License

MIDI Message Copyright (c) 2011-2015 Ari Russo, licensed under Apache License 2.0 (see the file LICENSE.midi-message)