Beginner's Guide to MIDI

MIDI topics

What is MIDI?

If you surf the internet at all regularly, the chances are you have inadvertently opened a web page with music playing in the background. Now your (reasonable) response may well be to close the page as quickly as possible, but if you're any sort of musician, be it composer or performer, or simply enjoy a bit of karaoke now and then, you may be interested to know that you have stumbled across a very useful resource indeed, namely, MIDI.

Turn on your computer speakers and click on the icon below to open a MIDI file. You can save the file to your computer if you click the icon with the right mouse button. You will then have a file with the extension .mid.

link to a MIDI file

A MIDI file is not a music file per se, but a set of instructions, called a sequence, to another instrument, telling it what to play. The word MIDI is an acronym: Musical Instrument Digital Interface, a set of commands to synthesizers to play certain notes at this pitch, that volume, and so forth. The format has been standardised these days: General MIDI (GM for short) uses up to sixteen "tracks" of data, and 128 different "voices", making it possible to represent music played by a single intrument, or a large band or orchestra. MIDI files are not the same as audio files. The latter can be thought of as computerised "tape recordings", which store the actual sounds made. There are no sounds in a MIDI file, rather, it is the modern, digital equivalent of the piano roll, and needs an instrument, such as an electronic keyboard or your computer's own synthesizer to play it.

MIDI sequencer

The illustration shows a MIDI file opened in Jazz++ MIDI sequencer, a program for making MIDI files. The top window shows the layout of music tracks and the instruments used to play them. The bottom window shows the notes represented as a piano roll.

I'll assume you like to sing - most people do. Or maybe you play an instrument. The nicest way to practice or perform is with a pianist and/or other players, but this isn't always possible, so an alternative is to use backing tracks. There are several advantages to using MIDI. Whereas editing digital audio is usually limited to global changes such as volume adjustments, MIDI files or "sequences" can be manipulated almost ad infinitum. Take, for example, a MIDI representation of your favourite song, which is in the wrong key for you. Changing the pitch of an audio file inevitably results in compromises to the speed, however MIDI can be transposed easily without affecting the playback in other ways. With MIDI, you can adjust the volume of each track, or just parts of a track, change the instruments, eliminate parts, alter notes, add new notes...the list goes on. Many MIDI files include lyrics which can be displayed with a suitable player, such as Van Basco's karaoke player, which is popular and free. And all this information is stored in tiny files of a few kilobytes at most. MIDI is a boon when it comes to learning new material: you can isolate individual parts, slow them down or repeat difficult phrases until you know them. Some choir masters make extensive use of MIDI for just that purpose. I have even heard of churches using MIDI files instead of an organist, though I don't know what the Organist's Union, if such an organisation exists, would say about that! Also, many composers use MIDI to preview their work before giving it to live instrumentalists, and sometimes incorporate sounds produced via MIDI into actual performances.

So what are the disadvantages? Well, the most obvious is not the fault of the MIDI itself, but the instruments used to play them. There are good sythesizers and, well, not such good ones, particularly those designed to use with computers. Thus MIDI is often dismissed as a lot of irritating, cheesy "muzak" all too often embedded* in web pages with no means of switching it off! Dedicated computer soundcards generally incorporate some sort of MIDI synthesizer, but most home computers these days rely on a "software" synthesiser provided by Microsoft: "Microsoft GS Wavetable SW Synth". This uses actual recorded sound samples to represent different instruments, and was a considerable improvement on the type of synthesis used on older computers. However it was designed to run on computers with much lower specifications than those we take for granted these days, and can be really only be considered "better than nothing". The good news is that there are several ways of improving MIDI playback. I have often had people fooled into thinking that they are hearing actual live recordings instead of pure, synthesized sound. There are some hints on the next page.

Another downside to MIDI relates to the democratic nature of modern internet use. MIDI sequences are so easy to produce and reproduce, as well as being tolerated by free web hosts who refuse to accept mp3s, they are ubiquitous. Like most of the material available online, the quality varies from great to horrible. Many people have been put off by some truly ghastly MIDI files, and never get to know their tremendous potential. Such a versatile resource should not be dismissed so easily.

Below are some links to MIDI files on the internet, as well as my favourite player. 

Useful MIDI LINKS

The Classical Archives
David Barnes - the best collection of Beatles files anywhere on the internet.
Van Basco's MIDI and karaoke player also has an excellent MIDI search engine.

*An example of an embedded MIDI file

Next page: Improving MIDI playback