The Basics of MIDI
MIDI stands for “musical instrument digital interface.” MIDI was conceived in the 1980s as a way for computers to control keyboards, and for keyboards to control each other. MIDI is the modern equivalent of a player piano. Player pianos used punched-out paper that the piano read and self-played from. MIDI is an electronic language that synthesizers turn into music. Even though keyboards are capable of producing some very complex sounds, the manner in which they produce sound is very simple.
Here is what a MIDI keyboard sees when you play any single note:
Note On: Turn on the note you've pressed (for example: Note On, C4)
Volume: Set the loudness (0–127)
Note Off: Stop the sound
MIDI has many other commands for controlling other parameters, which we don't need to get into here. The essential information is small and easy to transmit from keyboard to keyboard, or computer to keyboard. As you can see, it's pretty simple to have a keyboard controlled with MIDI. It's very much like the old player piano that reads rolls of punched-out paper.
Even better is that the commands sent to control MIDI are very small, just small lines of textlike code. Even twenty years ago computers could handle complex MIDI. MIDI is not just for keyboards anymore — samplers, virtual instrument plug-ins, sound modules, guitar synthesizers, and drum machines can all utilize MIDI technology.
In the early days of MIDI, keyboard players and pianists were the largest group of MIDI users. One of the joys of MIDI was that it could record full performances exactly as you played them, directly into the computer. It allowed a piano player easy access to computer score writing and sequencing. Since only commands were recorded, not audio, performers could easily control the performance on even the most minute levels! They could alter the timing of individual notes by milliseconds. You could, and many did, go nuts making everything “perfect.”
MIDI also worked in reverse — musicians could compose something on a computer either by entering notes in a score program like Finale or Sibelius. MIDI was used to bring the music to aural reality. The music programs sent out MIDI commands for the keyboards and sound modules to play back the onscreen score. MIDI allowed composers to hear pieces in a semirealistic fashion, especially if groups weren't present to perform them.
Drum machines are also MIDI capable, and many drum loops and beats can be composed on the computer and sent to the drum machine for playback. FIGURE 7-1 shows a MIDI keyboard.