What is Midi?
MIDI stands for Musical Instrument Digital Interface. It is a means of swapping information between suitably equipped electronic musical instruments, and PC’s. It is very important to realise that the information being transmitted is control information, not the actual sound itself. However, as you will see, the transmitting of this control information makes all sorts of things possible.
Assuming you have a MIDI keyboard, as you play all the information gets transmitted as a series of messages – which notes you pressed at which time, how hard you pressed them, when you used the pedal and so on. It’s a bit like formatting a piece of text in a Word Processor.
The information that is transmitted down the MIDI cable can then be used in all sorts of ways. Firstly it could be used to play an instrument other than the one you are playing – including software instruments on your computer. This means you can have a keyboard controller that contains no sounds of its own, but simply transmits your playing information and uses the synthesisers on your computer’s soundcard to make the sounds. The benefit of this is that a controller keyboard with full-sized, weighted keys, can be bought for a reasonable price compared to buying an expensive personal keyboard or digital piano, thus getting you started with computer music making on a real budget.
In addition, software can ‘record’ the information you transmit and make it available for you to edit graphically. This is the basis of many composing and notation packages. You simply play the keyboard in real-time, then get a graphical rendition of what you have played which you can then edit and play back. The information might be displayed as notation, or as a piano roll, or as a list of events. By editing, you can correct mistakes you have made, or transpose the whole piece, speed it up, slow it down, add extra tracks using different voices…the possibilities are only limited by your imagination. You don’t need to be able to play that well to get started – play one hand at a time if necessary, or very slowly, then use the software to correct mistakes, put two hands together, and speed the whole thing up. If you play by ear, then you don’t have to edit through notation, but can use the other graphical editing features of sequencers if you prefer.
A lot of music software takes the controller information it receives to do other things – like accompany you, or perhaps to check whether you have understood concepts in a tutor. Suppose you are trying to practise your scales – you can get software that will say whether you played the right notes. Suppose you want to learn a piece. If you have a perfect MIDI file of the piece (millions are available on the internet or for purchase on disk), you can compare your performance and gradually learn the correct notes, adjusting the tempo to suit
It is the MIDI standard that has made all these things possible, and gives you the opportunity to use your PC to help with your music making. MIDI devices all understand the same language no matter which manufacturer made them, so you can genuinely hook them all up together with ease.
Of course MIDI isn’t perfect. In the search for a general standard, compromises have had to be made, especially with the General MIDI sound set. (This is the standard set of sounds which increase the portability of MIDI files - your soundcard will almost certainly contain a General MIDI sound bank). There are ways to deal with this, by upgrading your sound card, or even using software sound modules. However, the benefits of being able to link all kinds of different equipment together, and share the results in MIDI files which will play back on any MIDI device cannot be underestimated. The amazing range of educational packages now available is a direct result of the MIDI protocol, and the far-sighted group of manufacturers who developed it.
This is a really brief intro to the world of MIDI - if you want to know more, then there is a fantastic guide to computer music making written by Cakewalk- The Desktop Music Handbook - which covers MIDI in depth, and also features a great guide to Digital Audio.