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General MIDI

General MIDI is a specification for musical synthesisers 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 simultanesouly; 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.

Table of contents
1 Minimal feature requirements
2 Parameter interpretations

Minimal feature requirements

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

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 Grand Piano
2 Bright Acoustic 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; on this channel, 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.