MIDI for the Masses

As I constantly explain to people in the computer audio mailing list that I moderate ( http://WebDevelopersJournal.com/subform.html) MIDI (Musical Instrument Digital Interface) is not an audio format, and does not record sound in any way, shape or form. Instead, it allows you to record and play back a set of instructions that a synthesizer, sound card, drum machine or other electronic instrument can use to create sound. A MIDI file is a list of actions to be performed, each action being a particular musical note (or other event) played at a particular time. It's conceptually very similar to a player piano.

You can create MIDI files with a sequencer program such as those made by Cakewalk, Cubase or Voyetra, or you can download them ready-made from various sites on the Web (remember, the same copyright restrictions that apply to graphics and audio files apply to MIDI files too). What you can't do with MIDI is record a voice, sound effect, or any kind of audio at all. At the risk of repeating a thrice-told tale, MIDI cannot record or play back audio. All it can do is send instructions to a sound card or other electronic musical instrument connected to the user's computer.

The advantage of MIDI for Web use is that, compared to audio files, MIDI files are tiny. Even a lengthy tune can be embedded in a Web page, and will start to play back very quickly. The disadvantage is that you have little control over how your MIDI file will actually sound on the receiving end (the same dilemma that applies to page layout and typography on the Web). To try to reduce the uncertainty, sound card makers have accepted a specification called "General MIDI."

General MIDI is a specification that assigns each instrument to a consistent MIDI program number, so that each musical part will play back on the type of instrument that it was intended for. A well-designed MIDI file includes a "program change" message at the beginning that tells the playback device to switch to the appropriate set of instruments (also called "voices" or "patches"). If your soundcard is not set up according to the General MIDI spec, then a part that was intended for a piano may come out as a kazoo, or a drum part may come out on the piccolo. All modern sound cards support General MIDI, so if your site visitor has a sound card, it's probable that your MIDI background music will play back on their system reasonably close to the way you intended (and if they have no sound card, it won't play back at all). The actual quality of the sound, of course, depends on the quality of their sound card and speakers. Considering that most users' sound cards are cheapies designed for games, a MIDI track is guaranteed to sound as cheesy as Velveeta to most Web site visitors.

Audio for the Worldwide Web
Audio for the Worldwide Web
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