
                  General MIDI (GM) and Roland's GS standard
                                       
    Original article in Electronic Musician 8/91 by Chris Meyer
    
     _________________________________________________________________
                                      
Brief Overview of Proposed General MIDI Level 1 Spec

   The heart of General MIDI (GM) is the Instrument Patch Map, shown in
   Table 1. This is a list of 128 sounds, with corresponding MIDI program
   numbers. Most of these are imitative sounds, though the list includes
   synth sounds, ethnic instruments and a handful of sound effects.
   
   The sounds fall roughtly into sixteen families of eight variations
   each. Grouping sounds makes it easy to re-orchestrate a piece using
   similar sounds. The Instrument Map isn't the final word on musical
   instruments of the world, but it's pretty complete.
   
   General MIDI also includes a Percusssion Key Map, show in Table 2.
   This mapping derives from the Roland/Sequential mapping used on early
   drum machines. As with the Instrument Map, it doesn't cover every
   percussive instrument in the world, but it's more than adequate as a
   basic set.
   
   To avoid concerns with channels, GM restricts percussion to MIDI
   Channel 10. Theoretically, the lower nine channels are for the
   instruments, but the GM spec states that a sound module must respond
   to all sixteen MIDI channels, with dynamic voice allocation and a
   minimum of 24 voices.
   
   General MIDI doesn't mention sound quality of synthesis methods.
   Discussions are under way on standardizing sound parameters such as
   playable range and envelope times. This will ensure that an
   arrangement that relies on phrsing and balance can play back on a
   variety of modules.
   
   Other requirements for a GM sound module include response to velocity,
   mod wheel, aftertouch, sustain and expression pedal, main volume and
   pan, and the All Notes Off and Reset All Controllers messages. The
   module also must respond to both Pitch Bend and Pitch Bend Sensitivity
   (a MIDI registered parameter). The default pitch bend range is +-2
   semitones.
   
   Middle C (C3) corresponds to MIDI key 60, and master tuning must be
   adjustable. Finally, the MIDI Manufacturers Association (MMA) created
   a new Universal System Exclusive message to turn General MIDI on and
   off (for devices that might have "consumer" and "programmable"
   settings). Table 3 summarizes these requirements.
   
   General MIDI has room for future expansion, including additional drum
   and instrument assignments and more required controllers. Also under
   discussion is an "authorizing document" that would standardize things
   such as channel assignments (e.g., lead on 1, bass on 2, etc.) and
   setup information in a MIDI file.
   
   Copies of the Level 1 Specification documents for General MIDI ($5
   each at last notice) are available from the Internation MIDI
   Association, 5316 West 57th Street Los Angeles, CA 90056, (213)
   649-6434. The first issue of the Journal of the MMA (back issues, $15
   each) contains an article by PassPort Designs and Stanley Junglieb
   about General MIDI.
   
     _________________________________________________________________
                                      
Roland's GS Standard

   When Warner New Media first proposed a General MIDI standard, most MMA
   members gave it little thought. As discussions proceeded, Roland
   listened and developed a sound module to meet the proposed
   specification. At the same NAMM show where the MMA ratified General
   MIDI Level 1, Roland showed their Sound Brush and Sound Canvas, a
   Standard MIDI File player and GM-compatible sound module.
   
   Some companies feel that General MIDI doesn't go far enough, so Roland
   created a superset of General MIDI Level 1, which they call GS
   Standard. It obeys all the protocols and sound maps of General MIDI
   and adds many extra controllers and sounds. Some of the controllers
   use Unregistered Parameter Numbers to give macro control over synth
   parameters such as envelope attack and decay rates.
   
   The new MIDI Bank Select message provides access to extra sounds
   (including variations on the stock sounds and a re-creation of the
   MT-32 factory patches). The programs in each bank align with the
   original 128 in General MIDI's Instrument Patch Map, with eight banks
   housing related families. The GS Standard includes a "fall back"
   system. If the Sound Canvas receives a request for a bank/program
   number combination that does not exist, it will reassign it to the
   master instrument in that family. A set of Roland System Exclusive
   messages allows reconfiguration and customization of the sound module.
   
   This means that a Roland GS Standard sound module will correctly play
   back any song designed for General MIDI. In addition, if the song's
   creator wants to create some extra nuance, they can include the GS
   Standard extensions in their sequence. None of these extensions are so
   radical as to make the song unplayable on a normal GM sound module.
   After all, compatibility is what MIDI - and especially General MIDI -
   is all about.
   
   Music authors interested in the GS Standard should contact Tom White
   at RolandCorp USA, 7200 Dominion Circle, Los Angeles, CA 90040, (213)
   685-5141.
   
     _________________________________________________________________
                                      
TABLE 1 - General MIDI Instrument Patch Map

   (groups sounds into sixteen families, w/8 instruments in each family)

Prog#     Instrument               Prog#     Instrument

(1-8        PIANO)                   (9-16      CHROM PERCUSSION)
1         Acoustic Grand             9        Celesta
2         Bright Acoustic           10        Glockenspiel
3         Electric Grand            11        Music Box
4         Honky-Tonk                12        Vibraphone
5         Electric Piano 1          13        Marimba
6         Electric Piano 2          14        Xylophone
7         Harpsichord               15        Tubular Bells
8         Clav                      16        Dulcimer

   (17-24      ORGAN)                      (25-32      GUITAR)
17        Drawbar Organ             25        Acoustic Guitar(nylon)
18        Percussive Organ          26        Acoustic Guitar(steel)
19        Rock Organ                27        Electric Guitar(jazz)
20        Church Organ              28        Electric Guitar(clean)
21        Reed Organ                29        Electric Guitar(muted)
22        Accoridan                 30        Overdriven Guitar
23        Harmonica                 31        Distortion Guitar
24        Tango Accordian           32        Guitar Harmonics

   (33-40      BASS)                        (41-48     STRINGS)
33        Acoustic Bass             41        Violin
34        Electric Bass(finger)     42        Viola
35        Electric Bass(pick)       43        Cello
36        Fretless Bass             44        Contrabass
37        Slap Bass 1               45        Tremolo Strings
38        Slap Bass 2               46        Pizzicato Strings
39        Synth Bass 1              47        Orchestral Strings
40        Synth Bass 2              48        Timpani

   (49-56     ENSEMBLE)                      (57-64      BRASS)
49        String Ensemble 1         57        Trumpet
50        String Ensemble 2         58        Trombone
51        SynthStrings 1            59        Tuba
52        SynthStrings 2            60        Muted Trumpet
53        Choir Aahs                61        French Horn
54        Voice Oohs                62        Brass Section
55        Synth Voice               63        SynthBrass 1
56        Orchestra Hit             64        SynthBrass 2

   (65-72      REED)                         (73-80      PIPE)
65        Soprano Sax               73        Piccolo
66        Alto Sax                  74        Flute
67        Tenor Sax                 75        Recorder
68        Baritone Sax              76        Pan Flute
69        Oboe                      77        Blown Bottle
70        English Horn              78        Skakuhachi
71        Bassoon                   79        Whistle
72        Clarinet                  80        Ocarina

   (81-88      SYNTH LEAD)                   (89-96      SYNTH PAD)
81        Lead 1 (square)           89        Pad 1 (new age)
82        Lead 2 (sawtooth)         90        Pad 2 (warm)
83        Lead 3 (calliope)         91        Pad 3 (polysynth)
84        Lead 4 (chiff)            92        Pad 4 (choir)
85        Lead 5 (charang)          93        Pad 5 (bowed)
86        Lead 6 (voice)            94        Pad 6 (metallic)
87        Lead 7 (fifths)           95        Pad 7 (halo)
88        Lead 8 (bass+lead)        96        Pad 8 (sweep)

   (97-104     SYNTH EFFECTS)                (105-112     ETHNIC)
 97        FX 1 (rain)              105       Sitar
 98        FX 2 (soundtrack)        106       Banjo
 99        FX 3 (crystal)           107       Shamisen
100        FX 4 (atmosphere)        108       Koto
101        FX 5 (brightness)        109       Kalimba
102        FX 6 (goblins)           110       Bagpipe
103        FX 7 (echoes)            111       Fiddle
104        FX 8 (sci-fi)            112       Shanai

   (113-120    PERCUSSIVE)                  (121-128     SOUND EFFECTS)
113        Tinkle Bell              121       Guitar Fret Noise
114        Agogo                    122       Breath Noise
115        Steel Drums              123       Seashore
116        Woodblock                124       Bird Tweet
117        Taiko Drum               125       Telephone Ring
118        Melodic Tom              126       Helicopter
119        Synth Drum               127       Applause
120        Reverse Cymbal           128       Gunshot

     _________________________________________________________________
                                      
TABLE 2 - General MIDI Percussion Key Map

   (assigns drum sounds to note numbers. MIDI Channel 10 is for
   percussion)

MIDI   Drum Sound                MIDI    Drum Sound
Key                              Key

35     Acoustic Bass Drum        59      Ride Cymbal 2
36     Bass Drum 1               60      Hi Bongo
37     Side Stick                61      Low Bongo
38     Acoustic Snare            62      Mute Hi Conga
39     Hand Clap                 63      Open Hi Conga
40     Electric Snare            64      Low Conga
41     Low Floor Tom             65      High Timbale
42     Closed Hi-Hat             66      Low Timbale
43     High Floor Tom            67      High Agogo
44     Pedal Hi-Hat              68      Low Agogo
45     Low Tom                   69      Cabasa
46     Open Hi-Hat               70      Maracas
47     Low-Mid Tom               71      Short Whistle
48     Hi-Mid Tom                72      Long Whistle
49     Crash Cymbal 1            73      Short Guiro
50     High Tom                  74      Long Guiro
51     Ride Cymbal 1             75      Claves
52     Chinese Cymbal            76      Hi Wood Block
53     Ride Bell                 77      Low Wood Block
54     Tambourine                78      Mute Cuica
55     Splash Cymbal             79      Open Cuica
56     Cowbell                   80      Mute Triangle
57     Crash Cymbal 2            81      Open Triangle
58     Vibraslap

     _________________________________________________________________
                                      
TABLE 3 - General MIDI minimum sound module specs

   Voices:
          A minimum of either 24 fully dynamically allocated voices
          available simultaneously for both melodic and percussive sounds
          or 16 dynamically allocated voices for melody plus eight for
          percussion.
          
   Channels:
          General MIDI mode supports all sixteen MIDI channels. Each
          channel can play a variable number of voices (polyphony). Each
          channel can play a different instrument (timbre). Keybased
          Percussion is always on Channel 10.
          
   Instruments:
          A minimum of sixteen different timbres playing various
          instrument sounds. A minimum of 128 preset for Intruments (MIDI
          program numbers).
          
   Note on/Note off:
          Octabe Registration: Middle C(C3) = MIDI key 60. All Voices
          including percussion respond to velocity.
          
   Controllers:
          
Controller #   Description
  1             Modulation
  7             Main Volume
 10             Pan
 11             Expression
 64             Sustain
121             Reset All Controllers
123             All Notes Off

Registered      Description
Parameter #
0               Pitch Bend Sensitivity
1               Fine Tuning
2               Coarse Tuning

   Additional Channel Messages:
          Channel Pressure (Aftertouch)
          Pitch Bend
          
   Power-Up Defaults:
          Pitch Bend Amount = 0
          Pitch Bend Sensitivity = +-2 semitones
          Volume = 90
          All Other Controllers = reset
          
     _________________________________________________________________
                                      
    (after Electronic Musician, 8/91 issue)
    
     _________________________________________________________________
                                      
   Heini Withagen, heiniw@dhp.nl
