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.
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
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 |