General MIDI - Definition


General MIDI - Definition

General MIDI is a specification for synthesizers which imposes several requirements beyond the more abstract MIDI standard. While MIDI itself does provide a protocol which ensures that different instruments can interoperate at a fundamental level (e.g. that pressing keys on a MIDI keyboard will cause an attached MIDI sound module to play musical notes), General MIDI (or GM) goes further in two ways: it requires that all GM-compatible instruments meet a certain minimal set of features, such as being able to play at least 24 notes simultaneously (polyphony); and it attaches certain interpretations to many parameters which were left unspecified in MIDI, such as defining instrument sounds for each of 128 program numbers.

General MIDI was first standardised in 1991, by the MIDI Manufacturers Association (MMA) and the Japan MIDI Standards Committee (JMSC), and has since been adopted as an addendum to the main MIDI standard. GM itself was later revised to become General MIDI 2, in 1999.

Other companies have created their own extensions to the original General MIDI standard, notably Roland's GS and Yamaha's XG.

Contents

1 Minimal feature requirements

2 Parameter interpretations

2.1 Program change events
2.2 Percussion sounds
2.3 Controller events
2.4 System Exclusive messages

3 External links

Minimal feature requirements

General MIDI (version 1) compatible instruments are required to be able to:

Allow 24 voices to be active simultaneously (including at least 16 melodic and 8 percussive voices)
Respond to note velocity
Support all 16 channels simultaneously (with channel 10 reserved for percussion)
Support polyphony (multiple simultaneous notes) on each channels

Parameter interpretations

GM Instruments must also obey the following conventions for program and controller events:

Program change events

This table shows which instrument sound corresponds to each program change number:

Piano: 1 Acoustic Piano 2 Bright Piano 3 Electric Grand Piano 4 Honky-tonk Piano 5 Electric Piano 1 6 Electric Piano 2 7 Harpsichord 8 Clavi Chromatic Percussion: 9 Celesta 10 Glockenspiel 11 Music Box 12 Vibraphone 13 Marimba 14 Xylophone 15 Tubular Bells 16 Dulcimer Organ: 17 Drawbar Organ 18 Percussive Organ 19 Rock Organ 20 Church Organ 21 Reed Organ 22 Accordion 23 Harmonica 24 Tango Accordion Guitar: 25 Acoustic Guitar (nylon) 26 Acoustic Guitar (steel) 27 Electric Guitar (jazz) 28 Electric Guitar (clean) 29 Electric Guitar (muted) 30 Overdriven Guitar 31 Distortion Guitar 32 Guitar harmonics Bass: 33 Acoustic Bass 34 Electric Bass (finger) 35 Electric Bass (pick) 36 Fretless Bass 37 Slap Bass 1 38 Slap Bass 2 39 Synth Bass 1 40 Synth Bass 2 Strings: 41 Violin 42 Viola 43 Cello 44 Contrabass 45 Tremolo Strings 46 Pizzicato Strings 47 Orchestral Harp 48 Timpani Ensemble: 49 String Ensemble 1 50 String Ensemble 2 51 Synth Strings 1 52 Synth Strings 2 53 Voice Aahs 54 Voice Oohs 55 Synth Voice 56 Orchestra Hit Brass: 57 Trumpet 58 Trombone 59 Tuba 60 Muted Trumpet 61 French horn 62 Brass Section 63 Synth Brass 1 64 Synth Brass 2

Reed: 65 Soprano Sax 66 Alto Sax 67 Tenor Sax 68 Baritone Sax 69 Oboe 70 English Horn 71 Bassoon 72 Clarinet Pipe: 73 Piccolo 74 Flute 75 Recorder 76 Pan Flute 77 Blown Bottle 78 Shakuhachi 79 Whistle 80 Ocarina Synth Lead: 81 Lead 1 (square) 82 Lead 2 (sawtooth) 83 Lead 3 (calliope) 84 Lead 4 (chiff) 85 Lead 5 (charang) 86 Lead 6 (voice) 87 Lead 7 (fifths) 88 Lead 8 (bass + lead) Synth Pad: 89 Pad 1 (new age) 90 Pad 2 (warm) 91 Pad 3 (polysynth) 92 Pad 4 (choir) 93 Pad 5 (bowed) 94 Pad 6 (metallic) 95 Pad 7 (halo) 96 Pad 8 (sweep) Synth Effects: 97 FX 1 (rain) 98 FX 2 (soundtrack) 99 FX 3 (crystal) 100 FX 4 (atmosphere) 101 FX 5 (brightness) 102 FX 6 (goblins) 103 FX 7 (echoes) 104 FX 8 (sci-fi) Ethnic: 105 Sitar 106 Banjo 107 Shamisen 108 Koto 109 Kalimba 110 Bagpipe 111 Fiddle 112 Shanai Percussive: 113 Tinkle Bell 114 Agogo Bells 115 Steel Drums 116 Woodblock 117 Taiko Drum 118 Melodic Tom 119 Synth Drum 120 Reverse Cymbal Sound effects: 121 Guitar Fret Noise 122 Breath Noise 123 Seashore 124 Bird Tweet 125 Telephone Ring 126 Helicopter 127 Applause 128 Gunshot

Percussion sounds

Channel 10 is reserved for percussion under General MIDI; this channel always sounds as percussion regardless of whatever program change numbers it may be sent, and different note numbers are interpreted as different instruments:

35 Bass Drum 2 36 Bass Drum 1 37 Side Stick 38 Snare Drum 1 39 Hand Clap 40 Snare Drum 2 41 Low Tom 2 42 Closed Hi-hat 43 Low Tom 1 44 Pedal Hi-hat 45 Mid Tom 2 46 Open Hi-hat 47 Mid Tom 1 48 High Tom 2 49 Crash Cymbal 1 50 High Tom 1 51 Ride Cymbal 1 52 Chinese Cymbal 53 Ride Bell 54 Tambourine 55 Splash Cymbal 56 Cowbell 57 Crash Cymbal 2 58 Vibra Slap

59 Ride Cymbal 2 60 High Bongo 61 Low Bongo 62 Mute High Conga 63 Open High Conga 64 Low Conga 65 High Timbale 66 Low Timbale 67 High Agogo 68 Low Agogo 69 Cabasa 70 Maracas 71 Short Whistle 72 Long Whistle 73 Short Guiro 74 Long Guiro 75 Claves 76 High Wood Block 77 Low Wood Block 78 Mute Cuica 79 Open Cuica 80 Mute Triangle 81 Open Triangle

Controller events

GM also specifies which operations should be performed by several controllers:

1 Modulation 7 Volume 10 Pan 11 Expression 64 Sustain 121 Reset all controllers 123 All notes off

The following Registered Parameter Numbers (RPNs) are also standardised:

0 Pitch bend range 1 Fine tuning 2 Coarse tuning

System Exclusive messages

Two GM system exclusive ("sysex") messages are defined: one to enable and disable General MIDI compatibility, on devices which also allow modes which are not GM-compatible; and the other to modify an instrument's master volume.

External links

MIDI Manufacturers Association (http://www.midi.org/) (MMA)
MIDI Technical Fanatic's Brainwashing Center (http://www.borg.com/~jglatt/)

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