MIDI Classics/MIDICLASSIC.iso/docs/midi.txt

Text File | 1994-09-19 | 16KB | 424 lines

Notes on MIDI

    Musical Instrument Digital Interface, or MIDI, was created in the
early 1980's as a way for musical instruments to communicate with each other.
Since it is a digital form of communication, computers soon were in the MIDI
loop.  In a little over ten years MIDI has become common on desktop PC's.
Musicians and nonmusicians alike are discovering how MIDI can transform a PC
into a home studio or add music to an application or presentation in a way
that is both easily customized and resource efficient.

    To communicate with each other, MIDI devices use a serial protocol
at a baud rate of 31.25kbs on 16 discreet channels.  The MIDI specification
designates 128 patch numbers, 128 controller numbers, and has a provision for
controlling other aspects of musical performance via pitch wheel and breath
controller data. The complete MIDI specification is a copyrighted document
and may be obtained from:

International MIDI Association
23634 Emelita St.
Woodland Hills, CA 91367

[phone]  voice
[phone]  fax

The cost as of the time of this writing is $11.50 (U.S.).


    MIDI data is stored in a file format known as Standard MIDI File or
MIDI File Format.  Music data in MIDI form are instructions that a MIDI
device, such as a synthesizer, will respond to. Since MIDI data is not a
recording of actual sound, most of its parameters can be altered, making
MIDI a truly interactive form of recorded music.  Some examples of how an
edited MIDI file can be used are:

1.  The key of all or part of a piece can be changed without changing the
    tempo.
2.  The tempo of all or part of a piece can be changed without changing the
    key.
3.  Verses, choruses, or even the entire piece can be repeated by using cut
    and paste functions found in most MIDI editing software.
4.  Individual tracks (instruments) can be muted, allowing for practice or
    performance by a solo musician.

    MIDI data is usually stored in one of two types of MIDI files. The
Type 1 MIDI file, which is most common, has individual instrument and
channel assignments on separate tracks.  This makes editing the file much
easier.  Type 0 files store all data on one track, with individual channel
data intact.  Please see the Glossary for a better understanding of tracks
and channels.  Since most MIDI sequencers have more than 16 tracks, it is
common for MIDI files to have several tracks assigned to the same MIDI
channel.  This allows an orchestral score with many instrumental parts to
stay within the confines of MIDI's 16 channels.

    The MIDI specification provides for system exclusive (also known as
SYS-EX) data exchanges.  These messages contain a manufacturer's ID number
at their beginning.  This ID number tells the devices in the MIDI signal path
which device the message is intended for, so other devices ignore it.  Sys-ex
messages are used for setting parameters on synth modules and transmitting
voice banks or individual patches.  For many synth modules, sys-ex messages
are the only way to access certain controls.  MIDI also supports a similar
feature called MIDI Sample Dump.  This provision allows transmission of
digital samples between samplers and computers via the MIDI port.





Glossary

Channel                 A data path for transmitting data in both directions.
            Think of it in terms of a television channel.  Data
            can be present on any or all channels at once, but
            only the data on channels that a device is set for
            will be recognized.

Controller              1. In software, a message that causes certain
            functions of a MIDI device to respond.  For instance,
            MIDI controller number 7 controls volume. When
            controller 7 is set for 127, volume output is at its
            maximum.
            2. In hardware, a MIDI controller is a keyboard that
            send MIDI data out to -other devices. It usually has
            no sound generating capabilities of its own.

FM                      Frequency Modulation synthesis.  A type of sound
            generation that uses simple waveforms modulating
            other simple waveforms to create complex waveforms.
            Within an FM device are Operators. An operator
            consists of a waveform generator and an envelope
            generator.  The envelope generator causes the loudness
            of the waveform to vary over time. Algorithms
            determine what operators' outputs feed into other
            operators. An operator whose output feeds into
            another operator is called a modulator. An operator
            whose output goes out of the synthesizer is called a
            carrier.  Think of operators as building blocks.  The
            more blocks you have stacked on each other, the more
            complex the sound can become. The Yamaha DX7 is the
            best known example of FM synthesis. In the multimedia
            world, the Adlib and Sound Blaster cards are known
            for their FM synthesis.

General MIDI            A standard for MIDI devices and software which uses
            certain sounds in certain patch locations. For
            instance,  patch 41 ( "1" based numbering) would be
            assigned to a violin sound.  A table of General MIDI
            patches are included in this document. The General
            MIDI standard also states the minimum number of
            simultaneous voices available, the MIDI messages that
            must be recognized, and assignments for rhythm
            instruments on Channel 10. The General MIDI standard
            is based largely the Roland Sound Canvas.

Hertz                   The measurement of sound frequency. It is also known
            as cycles per second.  Human hearing is generally
            regarded as being between 20 HZ and 20,000 HZ.

Key                     In music, the tonal base around which the music is
            based. A system of sharps (#) and flats (b) designate
            the key of a piece of music.

Meter                   In music, the designation of how time is divided,
            also known as time signature.  Music has an underlying
            beat. In 4/4 (called four four) time, there are four
            beats to every measure (or bar) and the quarter note
            receives one beat.

MPU 401                 Some of the first MIDI interfaces for IBM compatible
            computers were built by Roland Corp.  They became the
            de facto standard for which most MIDI software for
            the PC was written. Even though the MPU 401 is out of
            production, the current models of most PC MIDI
            interfaces still conform to the MPU 401 design.

MT32                    Roland device produced in the 1980's which helped
            pioneer the way for multimedia sound devices.  It
            used an advanced (at that time) form of synthesis
            to achieve more realistic instrument sounds than had
            been available in synthesizers.  Many products,
            especially computer games, used it as a standard for
            music authoring.  Most patch numbers on the MT32 are
            not the same as General MIDI, so playing a GM MIDI
            file on an MT32 or vice versa, will result in
            incorrect instrument assignments.

Octave                  The distance between two pitches whose frequencies
            are based on a ratio of 2:1 or 1:2.  On a piano
            keyboard, Middle C and C 5 are one octave apart with
            C5 being twice the frequency of Middle C.

Patch                   A term coined in the early days of synthesizers. Early
            synthesizers had individual modules that performed
            separate functions.  For a modular synth to make a
            sound, modules had to be connected together with
            patch cords.  The term has survived to this day.

Pitch                   The frequency of a sound.  The first A above Middle C
            on a piano is 440 Hertz.

Sample                  A sample is a digital representation of sound.  In
            sampling, the soundwave is measured at regular
            intervals and converted into a stream of numbers.Each
            number represents the loudness of the sound at each
            sampling interval.  Eight bit sampling allows for 256
            different levels of loudness. Sixteen bit sampling
            allows for 65,536 different levels of loudness.
            Audio CD's are recorded at a sampling rate of 44.1KHZ,
            at a 16 bit resolution, which means the analog signal
            is sampled 44100 times per second. Some sound cards
            are available with sample based MIDI playback sections
            in place of synthesizers.  Many will even allow the
            user to load in custom samples for use as instrument
            sounds.

Sequence                Music stored in a file format.  Most sequencers have
            the ability to store MIDI information in MIDI format
            as well as it's own proprietary file format.  A
            sequencer is a software program that reads, edits,
            and writes sequences.

Tempo                   The speed at which a musical performance is played.

Track                   In a sequencer, a track is similar to a track on a
            multi-track tape deck.  It is an area where
            individual instruments can be recorded. Using
            separate tracks for each instrument allows more
            flexibility in recording and editing.

Voice                   In FM synths, this term is sometimes used in place of
            PATCH. In other usage it refers to the number of
            notes played at any given time.  A 24 voice synth
            would be capable of playing a maximum of 24
            simultaneously.  Due to the nature of some synthesis
            technology, some devices capable of playing a certain
            number of voices when using simple patches or sounds
            can play fewer than their maximum when playing
            complex or layered sounds.

Wavetable               A form of synthesis that uses waveforms, stored in
            digital form  and usually stored in ROM.  Most
            wavetable devices mix different waveforms at
            different levels of volume and at different pitches
            to achieve somewhat realistic instrument sounds.

Wheel                   MIDI control element that will shift the pitch of a
            played note up or down.  Like PATCH,this term was
            used in the early days of synthesis. The MiniMoog, a
            very popular instrument with rock groups of the
            1970's and early 1980's, had two wheels at the left
            end of the keyboard.  One controlled modulation and
            one controlled pitch.



General MIDI Instrument Assignment

These instruments are valid on MIDI channels 1-9 and 11-16, except when used
in some Windows setups.  Microsoft has designated a Basic MIDI setup using
channels 13-15 as melodic instrument channels and channel 16 as the Basic
Setup percussion channel.  In an Extended MIDI setup, channels 2-9 are used
for melodic instruments and channel 10 is used for percussion.  This most
often applies to Windows sound drivers using the MIDI Mapper.  If you are
using an external device driven by an MPU 401 compatible interface, use the
Windows MPU 401 driver and all 16 MIDI channels will be available.

1- Bright Acoustic Piano
2- Electric Grand Piano
3- Honky Tonk Piano
4- Rhodes Piano
5- Chorused Piano
6- Harpsichord
7- Clavinet
8- Celesta
9- Glockenspiel
10-Music Box
11-Vibraphone
12-Marimba
13-Xylophone
14-Tubular Bells
15-Dulcimer
16-Hammond Organ
17-Percussive Organ
18-Rock Organ
19-Church Organ
20-Reed Organ
21-Accordion
22-Harmonica
23-Tango Accordion
24-Acoustic GTR(nylon)
25-Acoustic GTR(steel)
26-Electric GTR(jazz)
27-Electric GTR(clean)
28-Electric GTR(muted)
29-Overdriven GTR
30-Distortion GTR
31-Guitar Harmonics
32-Acoustic Bass
33-Electric Bass(fingered)
34-Electric Bass(picked)
35-Fretless Bass
36-Slap Bass 1
37-Slap Bass 2
38-Synth Bass 1
39-Synth Bass 2
40-Violin
41-Viola
42-Cello
43-Contrabass
44-Tremelo Strings
45-Pizzicato Strings
46-Orchestral Harp
47-Timpani
48-String Ensemble 1
49-String Ensemble 2
50-Synth Strings 1
51-Synth Strings 2
52-Choir Aahs
53-Voice Oohs
54-Synth Voice
55-Orchestra Hit
56-Trumpet
57-Trombone
58-Tuba
59-Muted Trumpet
60-French Horn
61-Brass Section
62-Synth Brass 1
63-Synth Brass 2
64-Soprano Sax
65-Alto Sax
66-Tenor Sax
67-Baritone Sax
68-Oboe
69-English Horn
70-Bassoon
71-Clarinet
72-Piccolo
73-Flute
74-Recorder
75-Pan Flute
76-Blown Bottle
77-Shakuhachi
78-Whistle
79-Ocarina
80-Lead 1(square)
81-Lead 2(sawtooth)
82-Lead 3(calliope)
83-Lead 4(chiff)
84-Lead 5(charang)
85-Lead 6(voice)
86-Lead 7(fifths)
87-Lead 8(bass+lead)
88-Pad 1(new age)
89-Pad 2(warm)
90-Pad 3(polysynth)
91-Pad 4(choir)
92-Pad 5(bowed)
93-Pad 6(metallic)
94-Pad 7(halo)
95-Pad 8(sweep)
96-FX 1(rain)
97-FX 2(soundtrack)
98-FX 3(crystal)
99-FX 4(atmosphere)
100-FX 5(brightness)
101-FX 6(goblins)
102-FX 7(echoes)
103-FX 8(sci-fi)
104-Sitar
105-Banjo
106-Shamisen
107-Koto
108-Kalimba
109-Bagpipe
110-Fiddle
111-Shanai
112-Tinkle Bell
113-Agogo
114-Steel Drums
115-Woodblock
116-Taiko Drum
117-Melodic Drum
118-Synth Drum
119-Reverse Cymbal
120-Guitar Fret Noise
121-Breath Noise
122-Seashore
123-Bird Tweet
124-Telephone Ring
125-Helicopter
126-Applause
127-Gunshot


Percussion Note Assignments

Middle C (C4) is MIDI note #60. This should be your reference point since
most MIDI keyboards do note go as low as MIDI note #27

Midi Note Number                Instrument
27                              High Q
28                              Slap
29                              Scratch Push
30                              Scratch Pull
31                              Sticks
32                              Square Click
33                              Metronome click
34                              Metronome Bell
35                              Kick Drum 2
36 (C2)                         Kick Drum 1
37                              Side Stick
38                              Snare 1
39                              Hand Clap
40                              Snare 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 (C3)                         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  (Middle C)                  Hi Bongo
61                              Lo Bongo
62                              Mute Hi Conga
63                              Hi Conga
64                              Lo Conga
65                              Hi Timbale
66                              Lo Timbale
67                              Hi Agogo
68                              Lo Agogo
69                              Cabasa
70                              Maracas
71                              Short Whistle
72  (C5)                        Long Whistle
73                              Short Guiro
74                              Long Guiro
75                              Claves
76                              Hi Woodblock
77                              Lo Woodblock
78                              Mute Cuica
79                              Open Cuica
80                              Mute Triangle
81                              Open Triangle
82                              Shaker
83                              Jingle Bells
84                              ---------------
85                              Castanets
86                              Mute Surdo
87                              Open Surdo