INTRODUCTION TO MIDI MIDI, the Musical Instrument Digital Interface, began as a serial interface bus designed to connect electronic musical instruments with each other and to computers. Now the term MIDI also refers to a file format (usually with the .MID extension) that can be used to store MIDI command codes as might be found on a MIDI bus. These files can be used to control a MIDI-compatible system with synthesizers, samplers, and other MIDI devices. MIDI FILES MIDI files support only instrumental music, not vocals or nonmusical audio. MIDI provides a powerful way to create and distribute instrumental music on the Internet. MIDIcompatible hardware and software are widely available for creating music and MIDI files. A major strength of MIDI files is their compact size. A 20-minute of MIDI instrumental music requires only 100KB of data compared to a 7.6minute of CD-quality audio that requires 80 MB of disk space. MIDI FILES The secret of a MIDI file’s compactness is that it contains no audio. Instead, it is a sequence of commands containing instructions on how to generate music. The commands in a midi file must be interpreted by hardware or software that can translate those commands into audio. When you think of MIDI think of sheet electronic music. For the music to be heard, the sheet music’s directives must be played on one or more musical instruments. The sheet music itself is not a sound, just as a MIDI file is not audio. PATCH A patch is a setup that creates the characteristic sounds of a musical instrument such as a piano or guitar. MIDI has 128 patch numbers or programs, which are codes that identify musical instruments. A patch map is a table used by a MIDI device to determine which instrument sound is assigned to which patch number. A patch map may assign program 41 to a violin, for example, program 33 to acoustic bass, and program 23 to a harmonica GENERAL MIDI A recommended specification for consumer electronic MIDI instruments that includes a uniform numbering of instrumental and drum sounds. One of the main problems that had caused headaches for MIDI users, was the inconsistent way that various instrument sounds were numerically arranged between different brands of MIDI synthesizers. Because of this inconsistency, it was difficult to share MIDI song files with one another. GENERAL MIDI About twenty years ago, Roland Corporation and Passport Designs spearheaded an effort to establish a new minimum of “industry standard” for MIDI instruments. The basic idea was to create a universal, specific preset instrument and drum setting that any manufacturer could easily include within their synthesizers. This new specification became known as “General MIDI.” FEATURES OF GENERAL MIDI Here are the important “minimum features” that a General MIDI compatible instrument will offer. A standard set of 128 sounds to choose from when composing musical soundtracks. The sounds are always arranged in a specific numerical order from brand-to brand. The capability of simultaneous playback of up to 16 separate instrument parts. The technical term is multitimbral – a GM instrument is, therefore, 16 part Multitimbral. A minimum of 64-voice playback. The technical term for this is polyphony – a GM instrument has at least 64 Voice Polyphony. At least one Standard Drum Set or Kit. GM supports ten drum sets or kits. The percussion sounds always have the same note assignments from brand-to-brand. FEATURES OF GENERAL MIDI How do you tell if your instrument is General MIDI compatible? Look for one (or more) of the following logos, either stamped or painted on the instruments itself. GENERAL MIDI GS XG SYNTHESIZERS A synthesizer is a piece of electronic hardware (or equivalent software running on a computer) that can combine and manipulate multiple tones in complex ways to create musical notes. Some sound cards, such as some of the SoundBlaster series from Creative Labs, have basic built-in synthesis capability. The terms multitimbral and polyphonic are used to describe synthesizers. SAMPLERS A device that “records” short, sound samples originally from real musical instruments, singer’s voice or even a dog’s bark. This unit also has a disk drive for loading and saving sound samples. A front-panel interface enables the user to edit samples. When a sampler receives a MIDI command, it executes it by playing one or more samples at a pitch and duration defined by the command MIDI SEQUENCERS The sequencer is what plays the music. It generates the commands sent to the synthesizer and samplers to generate the music (and the synthesizers and samplers generate the audio).