The Principle of MIDI Format

In order to better understand what the MIDI system is about, you should realise that it involves two kinds of communication devices:

• A sender (or controller)
  
  
It enables performance data to be sent to another device that understands MIDI.


• A receiver
  
  
It interprets the data sent and then plays it back.

The first category of devices encompasses "master" keyboards or those instruments equipped with an interface capable of converting analogue signals into MIDI notes, i.e. MIDI guitars, saxophones and drums, etc.

The second category mentioned includes expanders, or sound modules, that can interpret MIDI messages received from a master instrument or a specific software, via a computer equipped with a MIDI interface. The file produced by such an application is called a midifile.

In conclusion, you should bear in mind the following:

1. A midifile does not contain data describing a sound or an audio signal, but a musician's performance in the form of status and associated additional information, more generally known as messages.
   
   
2. A midifile can be used to reproduce sounds only if there is a receiving device or sound generator which can understand it.