What is MIDI?
Friday, March 23, 2007
By Stephane Brault
MIDI stands for Music Instrument Digital Interface. It is an industry-standard electronic communications protocol that allows electronic musical instruments, computers and other devices to communicate, control and synchronize with each other in real time. It does not transmit an audio signal or media - such as WAV or MP3 - it only transmits digital data like musical notes to play, pitch and intensity. It can also transmit parameters such as volume, vibrato, panning, cues and clock signal to set the tempo. As an electronic protocol, it has not changed much since it's introduction in 1983 and has been adopted throughout the industry since then.
In the late 70s, electronic musical devices were becoming more popular and affordable. However, devices from different manufacturers were not compatible with each others. Different interfacing models were developped but no standards were available.
In an attempt to solve this problem, audio engineer and synthesizer designer Dave Smith of Sequential Circuits Inc. proposed the MIDI standard in 1981. The industry received the proposition with enthusiasm and the MIDI Specification 1.0 was published in august 1983. Since then, Dave Smith is considered to be the "Father of MIDI". The MIDI technology has then been standardized and maintained by the MIDI Manufacturers Association (MMA).
All official MIDI standards are jointly developed and published by the MIDI Manufacturers Association (MMA). The primary reference for MIDI is The Complete MIDI 1.0 Detailed Specification, document version 96.1, available only directly from MMA in English, or from AMEI in Japanese.
Almost all music recordings today utilize MIDI as a key enabling technology for recording music. In addition, MIDI is also used to control hardware including recording devices as well as live performance equipment such as stage lights and effects pedals.
MIDI allows computers, synthesizers, MIDI controllers, sound cards, samplers and drum machines to control one another and to exchange data. Though modern computer sound cards are now capable of producing realistic instrument sounds, older sound cards had the reputation of producing sounds of dubious quality, therefore tarnishing the image of a computer as a MIDI instrument.
Almost all recordings today uses MIDI as a key enabling technology for recording music. MIDI is also used in live performances to control stage lights and effects pedals.
Synchronization of MIDI sequences is made possible by the use of MIDI timecode, an implementation of the SMPTE time code standard using MIDI messages, and MIDI timecode has become the standard for digital music synchronization.
A number of music file formats have been based on the MIDI bytestream. These formats are very compact; a file as small as 10 KB can produce a full minute of music. This is advantageous for applications such as mobile phone ringtones, and some video games.
The term "MIDI sound" has often been used as a synonym for "crappy sounding computer music", but this reflects a misunderstanding: MIDI does not define the sound, only the control protocol. The confusion has probably arisen because the quality of the General MIDI synthesis software and instrument banks included with some personal computers in the 1980's and 1990's could, perhaps, have been a little better. Today, we can replace General MIDI sounds by soundfonts (more about this in our next article).