Capabilities of MIDI Data

Written by: Karapet Melik-Barkhudarov on 3rd March 2010

cakewalk interface for midi

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General MIDI.

Most basic synths follow a specification called General MIDI or GM. This protocol specifies what programs (instruments) are available for the 16 channels. Drums are typically on channel 10. You can assign the rest the way you want. The basic GM set consists of 128 programs which always have the same program number. Piano is always program 1. 34 is always Picked Bass, 67 is always Baritone Sax. Ok, Here’s the Chart of GM sounds. Because there is this common reference, any file you make with GM can be played on any computer or synth that follows the GM spec. That’s what a MIDIFILE is. Its a sequence made up of tracks filled with timing information and NOTE ON/OFF information.

A “MIDI” or Midifile has no audio data again. It only has note and controller and time data. But because manufacturers follow this standard spec, it sounds the same, or similar, on different soundcards. Its possible to do a great composition with GM, but the limits are in the relatively small palette of 128 sounds. But its an excellent way to get started. After a while you might want better, more varied, or more specific sounds–that’s when you know its time to move on to standalone modules that give you hundreds, often thousands of instruments, or focus on specific genre’s like dance sounds, orchestral, hip hop, world fusion, R&B, etc.

Selecting Programs, Banks and Instruments

As we just saw, the GM bank has 128 instruments, or presets. If you get a bigger better, synth, you get more banks. My nearly maxed out Triton Rack for example has 16 banks of 128 instruments, or 2,048 instruments to choose from. My Pro 53 softsynth has 512 presets in 4 banks. Thanks to the Program change command I can select any instrument I want with the mouse from my sequencer. Now imagine the full MIDI rig with several softsynths, virtual drum machines and a good hardware synth. Thousands of sounds, any type of drum kit you want, all freely assignable to your MIDI tracks. I have been using a large MIDI rig for a long time and have never exhausted the possibilities.

The program change commands are not limited to synths, but can also be used to switch programs on effects boxes (such as reverb, delay, harmonizers, etc). Many studio devices can be switched internally by program changes. There are MIDI features on automated mixers, amp modelers, patchbays, even some compressors.