MIDI Musical Instrument Digital Interface

MIDI is the acronym for Musical Instrument Digital Interface, originally developed in 1983 by synthesizer manufacturers to allow musicians to connect synthesizers together. The protocol has permitted computers to communicate with a variety of music related instruments synthesizers, sound models, mixers and other sound processing equipment.

MIDI is a boon to composers and arrangers who develop scores quickly and easily. A MIDI file becomes a replacement for a printed music score that can be easily modified, played by different sound modules and printed for musicians to play.

The MIDI interface on an instrument includes three MIDI connectors - IN, OUT, and THRU. MIDI data streams can come from many sources  such as a keyboard, or a computer based MIDI sequencer that captures, stores, edits, and plays MIDI data. MIDI began with sixteen channels.  A polyphonic sound module, can assign different instruments to each channel.

The different sounds that are produced are described with different terms such as presets, patches, programs, voices and/or instruments.  Program (preset) numbers are assigned to each sound. Programs are assembled into banks, limited to 127 in MIDI, but many banks can be accessed, each with 127 programs. A program change message tells a device to change the instrument being used. For example, a sequencer could set up devices on Channel 1 to play fretless bass sounds, Piano on channel 2 and guitar on channel 3.

To create music, the essential MIDI data include:  Note On, Note Off, Velocity, Key Pressure, Channel,  Pitch Bend Change, Program Change, and  Control Change.  Additional controllers add MIDI data that influence sound production. Each controller is a 3 digit number followed by a value from 0 to 127.

The Korg Trinity is a music workstation that includes a keyboard , a polyphonic MIDI sound module and sequencer functions. You can compose, arrange and playback on the one instrument. It is popular as a performance keyboard and a studio instrument. It is limited to 16 channels (tracks). I use the Trinity as a keyboard that sends performance information to other sound modules and to Computer software such as Sonar 7.

The Proteus 2500 has two MIDI sets using A and B ports and can send or receive on 32 MIDI channels. The Proteus also has a built sequencer. Its special power is the production of rich sound, impeccable mixes and generous polyphony.

The MIDI event list is mostly numbers that would deter a beginner. I've used event lists since the beginning of MIDI and find them very useful especially when I start with a MIDI score that someone else created. I remove most of the controlled information and all the patch changes since my arrangement will head in a different direction and my instrument assignments will be different.

Composing with MIDI