A Beginner's Guide To MIDI

Member of the Music HyperBanner !

What Is M.I.D.I.?
Having asked the question its probably easier to start by looking at what M.I.D.I. isn't!
The first possible surprise is that M.I.D.I. isn't a sound file format. It doesn't carry the same sort of information as a .WAV or .AIFF file for instance.
.WAV files contain digital recordings of real sounds, similar, in a way, to recordings stored on a CD. M.I.D.I. files don't contain this sort of information at all.
M.I.D.I. is actually a control system. A M.I.D.I. file contains instructions to perform particular commands.
A Bit Of History
The M.I.D.I. protocol was developed by musical instrument manufacturers in order to make the connection of different models and makes of instrument easier. Until this point it was difficult, for instance, to play one synthesiser from the keyboard of another. This meant that layering sounds was difficult, and that in order to have access to a wide variety of sounds the keyboard player had to be surrounded by synthesisers.
M.I.D.I. was devised as a Universal Control System, in other words, a way of one synthesiser controlling another, irrespective of the make and model of either. At its simplest level, when a note is pressed on the master keyboard in a M.I.D.I. setup, it will transmit an instruction to the instruments that are connected to it saying "play this note", and the receiving instrument(s) will respond.
So, a M.I.D.I. file simply contains the instructions for a receiving instrument. It transmits these instructions in the form of numbers, and in this way it allows musical instruments to talk to each other. It is an interface. This, of course, is where the term M.I.D.I. comes from, since it stands for:
Musical Instrument Digital Interface
One of the first results of the development of M.I.D.I. was the removal of keyboards from synthesisers. This began the proliferation of the M.I.D.I. Module. These usually come in the form of 19" rack mountable boxes (such as the Emu Vintage Keys, or Novation Bass Station) so that they can be easily integrated into music studios, but can actually take all sorts of shapes and sizes.