Electronic Music

The Musical Instrument Digital Interface (MIDI)

changed just about everything

By Carter B. Horsley

In olden days, a glimpse of cable was something shocking.

Nowadays, however, it simply means Techno-Artist-at-Work.

The Musical Instrument Digital Interface (MIDI) was created in 1983 by the makers of several major synthesizers to permit their instruments to trigger sounds on other instruments, linked by cable, to create a richer, layered sound. Combine two adequate organ sounds on different instruments, for example, and, presto, you might get a more impressive and possibly better sound! All connected instruments, of course, have to have the same connectors and their hardware guts have to have been programmed to receive and send data over such connectors.

Fortunately, the creators of MIDI were far more brilliant than they ever realized for their standard provided a lot of information transfer electronically via fairly standard 5-pin cables.

As it evolved, the MIDI cables were able to transfer data simultaneously on 16 different channels. Each channel could have 128 categories, or subchannels, of information! Each category, or subchannel, could have up to 40,000 different values!

Theoretically, therefore, a musician could control 16 different instruments, one assigned to each channel, and play up to 128 notes simultaneously on each instrument and each note could have up to 128 different controllers and each controller could have up to 40,000 levels of sensitivity!

That is a lot of information, and in practice such an network would slow down a bit and might even "crash," but thankfully most musicians don't have enough fingers, toes, knees, noses, elbows and ears and the like to control everything all at once.

What was really spectacular about MIDI, moreover, was not so much the ability to layer instruments, but to transfer the performance data of a musician's playing, as opposed to the audio data coming out of the musician's instrument, to a computer for storage, playback, and editing.

This capability led directly to the emergence of the music software industry that produced not only "sequencer" programs that transcribed the performances on MIDI-equipped instruments connected by MIDI cables to the computer, but also the manipulation and even random programming of the synthesizer's sounds. In time, it has even lead to music notation and composition programs that can print out performances in standard music notation and make harmonic transpositions and even stylistic embellishments of the music played.

Before long, not only were music instruments being equipped with MIDI interfaces, but also sound enhancement machines, such as reverberation units, and mixers and lighting devices.

The possibilities are very broad and some musicians have applied MIDI technology not only to all kinds of keyboards, but also to guitars, violins, wind instruments, gloves, and tap-dance shoes.

Although synthesizers, which are electronic music instruments, have been around for most of the 20th Century, they did not begin to enter the mainstream until Robert Moog produced his famous Minimoog in the 1960's. What previously required a large room fill of expensive electronic equipment suddenly became available in a wooden case the size of a briefcase and it produced marvelous, to this day, sounds.

Most of the early synthesizers, including the Minimoog, were relatively simple with lots of knobs that changed the quality of the sound and playing their small keyboards turned a note on or off. Synthesis has come a long way and the three dozen or so sound controller parameters of the Minimoog have given way to several hundred sound parameters on some of the new instruments, which also, very importantly, are capable of 128 levels of volume per keystroke rather than just off and on. (Unfortunately, the velocity sensitivity of different synthesizers varies considerable, but software programs have taken that into account and can make adjustments if necessary and some instruments have switchable velocity response settings as well.)

Only 16 different instruments at one time? That's not much of an orchestra, some classical musicians, who have not worked with synthesizers, might say. Since, however, a synthesizer can be programmed to have one keystroke sound like a 20-piece violin section and since many different synthesizers can be programmed to respond to the same MIDI channel and since 128 drum sounds can easily, relatively, be programmed to play on only one MIDI channel, the MIDI orchestra is not all that unimpressive, especially since one serious electronic musician can play all the parts, create the composition and its arrangement and notate it and enhance its sonic ambience and record it as long as he/she pays the electricity bill.

Furthermore, in the last few years most synthesizers now are capable of playing up to 16 parts/channels simultaneously and can produce 64 sounds simultaneously. The number of sounds can be confusing as some "sounds" are actually made up of several "voices." Indeed, many of the newer synthesizers have a "voice" architecture that is composed of 4 "tones," but different manufacturers are not consistent in their architectures or nomenclatures. Most 64-voice synthesizers on the market today can play 16 4-tone sounds simultaneously, but some sounds can sound quite wonderful with just one tone. Indeed, the complexity of the "performance" mode MIDI implementation on the newer synthesizers is quite daunting.

MIDI, then, is a marvelous and glorified piano-roll of amazing precision, nuance and sensitivity.

Robert Moog's original Minimoog, which as an analog rather than a digital instrument, was probably capable of producing a few quadrillion distinct sounds. The newer instruments have exponentially expanded that sonic universe and it is safe to say that synthesizers are infinite machines in terms of their exciting aural universes.

MIDI simply blows the mind and in the process has made music software the most astonishingly powerful of all personal computer uses. This is all the more remarkable because it does not require high-powered processing, unless, of course, you are using the newer multi-MIDI ports that provide multiples of 16 channels and have set loose a Rachmaninoff on a sequencer program in which case a Pentium will be required.

MIDI data is miniscule compared to digitally recording audio in wav. files. One minute of stereo audio recording at Compact Disc quality (44,000 sound pictures per second at 16-bit recording size) takes up about 10 megabytes of data storage. A 15-minute, highly complex, symphonic MIDI piece might only take 200K, by comparison.

The Internet explosion is beginning to include some programs that can "stream" MIDI files, similar to RealAudio's streaming audio. Most personal computer soundcards incorporate synthesizers on a chip as well as have the capacity to have MIDI connectors attached. The City Review will report and demonstrate such technology in the not distant future.


See The City Review article on synthesizers

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