General MIDI

General MIDI or GM is a specification for synthesizers which imposes several requirements beyond the more abstract MIDI standard. While MIDI itself provides 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 and control messages 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. It has largely become 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 channel

Parameter interpretations

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

Program change events

The following table shows which instrument sound corresponds to each program change number. Note that for purposes of computer programming, this table should start at 0 instead of 1 and thus use all of the 7-bit range (0-127) allowed by the MIDI program change event. It should also be noted that some MIDI keyboards with displays show these program numbers as in the table (1-128), while others show the range as coded (0-127).

Melodic sounds

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 Clavinet 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 Strings (continued): 49 String Ensemble 1 50 String Ensemble 2 51 Synth Strings 1 52 Synth Strings 2 53 Choir 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 Bag pipe 111 Fiddle 112 Shanai Percussive: 113 Tinkle Bell 114 Agogo 115 Steel Drums 116 Woodblock 117 Taiko Drum 118 Melodic Tom 119 Synth Drum Sound effects: 120 Reverse Cymbal 121 Guitar Fret Noise 122 Breath Noise 123 Seashore 124 Bird Tweet 125 Telephone Ring 126 Helicopter 127 Applause 128 Gunshot

Percussion notes

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: [http://www.indiana.edu/~emusic/cntrlnumb.html] [http://www.midisite.com/info/synth/Control.htm]

1 Modulation
6 Data Entry MSB
7 Volume
10 Pan
11 Expression
38 Data Entry LSB
64 Sustain
100 RPN LSB
101 RPN MSB
121 Reset all controllers
123 All notes off

RPN

Setting Registered Parameters requires sending (numbers are decimal):
#two Control Change messages using Control Numbers 101 and 100 to select the parameter, followed by
#any number of Data Entry messages of one or two bytes (MSB = Controller #6, LSB = Controller #38), and finally
#an "End of RPN" message

The following global Registered Parameter Numbers (RPNs) are standardised [ [http://www.midi.org/about-midi/table3.shtml MIDI Messages Table 3 ] ] (the parameter is specified by RPN LSB/MSB pair and the value is set by Data Entry LSB/MSB pair):

0,0 Pitch bend range
1,0 Channel Fine tuning
2,0 Channel Coarse tuning
3,0 Tuning Program Change
4,0 Tuning Bank Select
5,0 Modulation Depth Range
127,127 RPN Null

For example: RPN control sequence to set coarse tuning to A440 (parm 2, value 64):
101:0, 100:2, 6:64, 101:127, 100:127

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.

GS extensions

The first GM synthesizer in Roland Sound Canvas line featured a set of extensions to General MIDI standard. The most apparent addition was the ability to address multiple banks of sounds by using additional pair of controllers, cc#0 (Bank Select MSB) and cc#32 (Bank Select LSB), to specify up to 65536 'variation' sounds.

Other most notable features were 9 Drum kits with 14 additional drum sounds each, Control Change messages for controlling the send level of sound effect blocks (cc#91-94), entering additional parameters (cc#98-101), portamento, sostenuto, soft pedal (cc#65-67), and model-specific SysEx messages for setting various parameters of the synth engine.

General MIDI Level 2

In 1999, the standard was once again updated to include more controllers, patches, RPNs and SysEx messages. Here's a quick overview of the changes in comparison to GM/GS:

* Number of Notes - minimum 32 simultaneous notes
* Simultaneous Percussion Kits - up to 2 (Channels 10/11)
* Additional 128 melodic sounds are included in variation banks, for a total of 256
* 9 GS Drum kits are included
* Additional Control Change messages
** Filter Resonance (Timbre/Harmonic Intensity) (cc#71)
** Release Time (cc#72)
** Brightness/Cutoff Frequency (cc#74)
** Decay Time (cc#75)
** Vibrato Rate (cc#76)
** Vibrato Depth (cc#77)
** Vibrato Delay (cc#78)
* Registered Parameter Numbers (RPNs)
** Modulation Depth Range (Vibrato Depth Range)
*Universal SysEx messages
** Master Volume, Fine Tuning, Coarse Tuning
** Reverb Type, Time
** Chorus Type, Mod Rate, Mod Depth, Feedback, Send to Reverb
** Controller Destination Setting
** Scale/Octave Tuning Adjust
** Key-Based Instrument Controllers
** GM2 System On

Additional melodic instruments can be accessed by setting CC#32 to 121 and then using CC#0 to select the bank before a Program Change. The most expanded group is Acoustic Pianos.

ee also

* Comparison of MIDI standards
* Soundfont

References

External links

* [http://www.midi.org/ MIDI Manufacturers Association] (MMA)
* [http://www.borg.com/~jglatt/ MIDI Technical Fanatic's Brainwashing Center]
* [http://www.voidaudio.net/ The Void: PC audio resource]
* [http://www.midisite.co.uk/ MIDIsite] a search engine for free midi files on the Internet
* [http://www.kuhmann.com/Yamaha.htm Disklavier World] Public Domain MIDI-music in FIL (e-SEQ format) for YAMAHA Disklavier pianos ~ live performances!