MIDI - an introduction

To get the best out of Mozart's play-back it is useful to know something of the way MIDI instructions work. Here is a gentle introduction.



A number of MOZART aficionados have asked about MOZART's MIDI capability. In the first instance, MOZART was for printing music but its expanding MIDI features are also clearly proving popular. In order to get the best out of playback it is very useful to know a little of the way MIDI works.

The following very basic background information may prove helpful to those with main interests in acoustic music, but who suddenly find that a basic knowledge of MIDI would be useful.   On the other hand, if you're a programmer interested in the real technical details of MIDI file specifications, then one of the clearest references we've found on the net is at:

MIDI Technical Fanatic's Brainwashing Center.

MIDI concepts

MIDI stands for Musical Instrument Digital Interface and was originally conceived for communication between electronic musical instruments. A MIDI synthesiser, such as the one on your computer's sound card, takes MIDI instructions and synthesises the sounds according to those instructions. The quality of the sound you hear depends entirely on the quality of the synthesiser. The synthesiser can be  an internal hardware component on a sound card, an external hardware device, or just software: a program running in the background on your computer.  (See also: MIDI setup.)

MIDI has 16 independent channels on which music can be played simultaneously (and nowadays just about all synthesisers can use all of them).  Each MIDI channel can be set to play with a different "voice" (sometimes called a "patch") but more than one channel can be set to the same if desired. 

More than one note can be played simultaneously on any channel. (The maximum number is again determined by your synthesiser.)

MIDI files contain a simple sequence of MIDI instructions each of which is time stamped with the amount of time which must be allowed to elapse since the previous instruction. For example, two of the commonest instructions are note on and note off instructions. These are effectively commands of the form: "start playing the D above middle C on channel 13", and "stop playing the D above middle C on channel 13". The duration of the note you will hear is determined by the time stamp on the second instruction (and any intervening ones). An immediate consequence for MOZART playback is that if you play more than one part on the same channel, then the "note-off" messages from one part can interfere with the other. So, even if you want the same voice on two parts, it can be advisable to use different MIDI channels in order to avoid this interference.

At the most fundamental level there are 128 different possible voices and at one time every instrument/synthesiser manufacturer had completely different ideas about what sounds 1-128 should be. Nowadays most sound cards confom to the "General MIDI" standard which defines names for each of these. These are the ones listed in MOZART's MidiOptions dialogue box, and they are listed below.  Any MIDI based system allows you to choose which voice is played on which MIDI channel. In addition MOZART allows you to assign a MIDI channel to a part on your printed score.


Percussion instruments can be separated into two classes: those of definite, and those of indefinite pitch.   Percussion instruments of definite pitch (eg xylophone, marimba, glockenspiel, vibraphone, tubular bells, timpani,...) are treated by MIDI just as any other instrument.  But MIDI has a special way of treating instruments of indefinite pitch (drums, cymbals, wood blocks, maracas,...).  For a discussion of the latter, see MIDI percussion.

Voices defined by the General MIDI standard

In the list which follows, the voices are numbered 1-128. Sometimes you may see them numbered 0-127 which is the internal representation used by computer programs.

001 Acoustic Grand Piano
002 Bright Acoustic Piano
003 Electric Grand Piano
004 Honky-tonk Piano
005 Rhodes Piano
006 Chorused Piano
007 Harpsichord
008 Clavinet
009 Celesta
010 Glockenspiel
011 Music Box
012 Vibraphone
013 Marimba
014 Xylophone
015 Tubular Bells
016 Dulcimer
017 Hammond Organ
018 Percussive Organ
019 Rock Organ
020 Church Organ
021 Reed Organ
022 Accordion
023 Harmonica
024 Tango Accordian
025 Acoustic Guitar (nylon)
026 Acoustic Guitar (steel)
027 Electric Guitar (jazz)
028 Electric Guitar (clean)
029 Electric Guitar (muted)
030 Overdriven Guitar
031 Distortion Guitar
032 Guitar Harmonics
033 Acoustic Bass
034 Electric Bass (finger)
035 Electric Bass (pick)
036 Fretless Bass
037 Slap Bass 1
038 Slap Bass 2
039 Synth Bass 1
040 Synth Bass 2
041 Violin
042 Viola
043 Cello
044 Contrabass
045 Tremolo Strings
046 Pizzicato Strings
047 Orchestral Harp
048 Timpani
049 String Ensemble 1
050 String Ensemble 2
051 Synth Strings 1
052 Synth Strings 2
053 Choir Aahs
054 Oohs
055 Synth
056 Orchestra Hit
057 Trumpet
058 Trombone
059 Tuba
060 Muted Trumpet
061 French Horn
062 Brass Section
063 Synth Brass 1
064 Synth Brass 2
065 Soprano Sax
066 Alto Sax
067 Tenor Sax
068 Baritone Sax
069 Oboe
070 Cor Anglais
071 Bassoon
072 Clarinet
073 Piccolo
074 Flute
075 Recorder
076 Pan Flute
077 Bottle Blow
078 Shakuhachi
079 Whistle
080 Ocarina
081 Lead 1 (square)
082 Lead 2 (sawtooth)
083 Lead 3 (caliope lead)
084 Lead 4 (chiff lead)
085 Lead 5 (charang)
086 Lead 6 ()
087 Lead 7 (fifths)
088 Lead 8 (brass + lead)
089 Pad 1 (new age)
090 Pad 2 (warm)
091 Pad 3 (polysynth)
092 Pad 4 (choir)
093 Pad 5 (bowed)
094 Pad 6 (metallic)
095 Pad 7 (halo)
096 Pad 8 (sweep)
097 FX 1 (rain)
098 FX 2 (soundtrack)
099 FX 3 (crystal)
100 FX 4 (atmosphere)
101 FX 5 (brightness)
102 FX 6 (goblins)
103 FX 7 (echoes)
104 FX 8 (sci-fi)
105 Sitar
106 Banjo
107 Shamisen
108 Koto
109 Kalimba
110 Bagpipe
111 Fiddle
112 Shanai
113 Tinkle Bell
114 Agogo
115 Steel Drums
116 Woodblock
117 Taiko Drum
118 Melodic Tom
119 Synth Drum
120 Reverse Cymbal
121 Guitar Fret Noise
122 Breath Noise
123 Seashore
124 Bird Tweet
125 Telephone Ring
126 Helicopter
127 Applause
128 Gunshot



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