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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. 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 sounds that are produced are described by 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 128, but many banks can be accessed, each with 128 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 MIDI event list is mostly lists of 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 filter out the controller information and all the patch changes since my arrangement will head in a different direction and my instrument assignments will be different.

My studio setup varies with the project. The essential tools are the Korg Trinity, The Proteus 2500 and a computer with Sonar software. MIDI information flows from the keyboard to the computer ( via an EMU 1820 docker) where it is recorded and edited in Sonar. Sonar sends the revised MIDI information to the Trinity and the Proteus which both play the music. The Audio out from the 2 modules returns to the computer (as digital audio) where it is recorded on audio tracks in Sonar. In other words Sonar sends midi out and receives audio in return.

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. I use the Trinity as a keyboard that sends performance information to other sound modules and to Computer software such as Sonar.

The Proteus 2500 lacks a keyboard, but 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.

Learn More About  Composing with MIDI