MIDI

For more information, see the following topics:

MIDI Terms

Common Misconceptions About MIDI

MIDI in Pro Tools

MIDI (Musical Instrument Digital Interface) is a communication protocol for musical instruments. This industry standard enables connections between a variety of devices from different manufacturers. Examples of MIDI-compatible equipment include synthesizers, sound modules, drum machines, MIDI patch bays, effects processors, MIDI interfaces, MIDI control surfaces, and MIDI sequencers.

MIDI devices are equipped with 5-pin DIN connectors, labeled as either IN, OUT, or THRU. The MIDI OUT port transmits messages. The MIDI IN port receives messages. The MIDI THRU outputs whatever is received from the IN port. MIDI devices are connected with MIDI cables that are available at most music stores.

USB and FireWire-compatible MIDI devices send and receive MIDI messages to and from the computer over USB or FireWire.

 

MIDI signal flow

Not all devices will have all three MIDI ports (IN, OUT, and THRU).

The MIDI protocol provides 16 channels of MIDI per port. A single MIDI cable can transmit a separate set of messages for each of the 16 channels. These 16 channels can correspond to separate MIDI devices or to multiple channels within a single device (if the device is multitimbral). Each channel can control a different instrument sound. For example, bass on channel 1, piano on channel 2, and drums on channel 10. Similar to a multitrack tape recorder, a MIDI sequencer can record complex arrangements—even using only a single multitimbral keyboard.