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What is MIDI?

MIDI Connections Chart
MIDI In/Out through a sound card or direct via USB connection

M.I.D.I. – Musical Instrument Digital Interface

Basically, MIDI is a computer language used in networking two or more devices together. The specific devices we are most often referring to when discussing MIDI are musical computers, like synthesizers or signal processors. Essentially this means that you can hook up two musical devices and have them “communicate” with each other.

Some Basic Concepts
You don’t need to understand nuclear fusion to get a grasp on this MIDI stuff, there are just a few basic concepts you have to grasp.

  1. MIDI information IS NOT audio information. This is a hang up for many people who are just starting out in the music and audio arena. MIDI is merely a set of numerical instructions that are sent and received between the devices. The musical devices then translate this data into meaningful commands. So when a MIDI command is sent from one device to another, the signal is telling the second device which notes to play, how long to hold them, which sounds to use… etc.
  2. You need to understand how the flow of MIDI information works. MIDI data is sent out of the “OUT” port, MIDI data is received at the “IN” port. So for example if you want to send a MIDI data from a sequencer to a synthesizer the cables would connect on the OUT of the sequencer (because info is coming out) to the IN of the synthesizer (because the synth is receiving info). This can be confusing at first because the temptation is to plug the IN of one machine directly into the IN of another. But if you do that, you are not going to get any sound…. Ever.
  3. Channels – MIDI data transmits on 16 different channels. This allows for 16 different sets of MIDI data to be sent at once, which means a sequencer could control up to 16 different instruments at one time. Typically each instrument would be sent separately on a different channel. For example, drum track information is usually sent on channel 10 and so would play back on channel 10, Bass guitar sounds are usually on channel 2, synth on 4 and so on. You just have to make sure that the synthesizer that is receiving the channels has the correct sound selected for that channel.

Because MIDI does not carry with it the actual audio sound data, but just the note commands, midi files are extremely light and compact. A large number of songs can take up a relatively small amount of space on a disk or hard drive. This reason, along with it’s versatility makes MIDI an ideal language for almost any musician, and especially those who are on the road for performances or deal in large volumes of music.