"General MIDI" is not the same as MIDI. Where MIDI is a
language, a file format, and a connector specification, the "General MIDI System Level 1" specification
-- also known as "GM", "General MIDI 1" and "GM1"
-- defines specific features of a MIDI instrument.
Without General MIDI, playback of MIDI files created on one MIDI
instrument might sound totally different on a different MIDI
instrument, because the only sound definition in MIDI is a sound
number (Program Number), not the actual characteristics of the sound.
GM helped establish a consistent level of performance compatibility among MIDI
instruments by establishing that specific sounds should be selected by
certain Program Numbers, paving the way for MIDI data to be used in
computer games and cell phones.
Note: The General MIDI (GM1) specification was superceded in 1999 by
General MIDI 2 which supports additional features and
capabilities commonly available. However, GM1 remains a popular format for lower-cost synthesizers and is commonly used for music distributed as Standard MIDI Files.
General MIDI Lite is an even lower-cost version of
GM developed specifically for use in low-power portable devices such
as cell phones.
To be GM1 compatible, a GM1 sound generating device (keyboard, sound module, sound card, IC, software program or other product) must meet the General MIDI System Level 1 performance requirements outlined below, instantaneously upon demand, and without additional modification or adjustment/configuration by the user.
GM1 Developer Information
- Voices: A minimum of either 24 fully dynamically allocated voices are available simultaneously for both melodic and percussive sounds, or 16 dynamically allocated voices are available for melody plus 8 for percussion. All voices respond to velocity.
Channels: All 16 MIDI Channels are supported. Each Channel can play a variable number of voices (polyphony). Each Channel can play a different instrument (sound/patch/timbre). Key-based percussion is always on MIDI Channel 10.
Instruments: A minimum of 16 simultaneous and different timbres playing various instruments. A minimum of 128 preset instruments (MIDI program numbers) conforming to the
GM1 Instrument Patch Map and 47 percussion sounds which conform to the
GM1 Percussion Key Map .
Channel Messages: Support for continuous controllers 1, 7, 10, 11, 64, 121 and 123; RPN #s 0, 1, 2; Channel Pressure, Pitch Bend.
Other Messages: Respond to the data entry controller and the RPNs for fine and course tuning and pitch bend range, as well as all General MIDI Level 1 System Messages.
GM Developer Guidelines document describes additional recommendations and clarifications of the GM Specification for content producers and device makers, to insure improved compatibility among GM products.
The GM1 Logo was created to insure consumer recognition for products that meet the General MIDI Level 1 Specification. The GM Logo is the property of the MMA and AMEI and must be used in accordance with guidelines established to insure the value of the GM Logo for our members and for the consumer.