Guide to the MIDI Software Specification

*  Last updated : Thu 20 Jan 2000  *

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Status bytes are identified due to their top bit being set. Consequently data bytes contain 7-bit values (0-127).

There are two main types of status bytes : Channel messages and System messages.

Channel messages use the lower 4 bits of the status byte to address 1 of 16 MIDI channels and the upper 4 bits to encode the specific message. A device can receive messages on more than one channel (known as voice channels), dependant on its mode of operation. However, there is a particular channel referred to as its base channel upon which it receives commands about which mode it should operate in and which voice (sound) it should use. Channel messages are sub-divided into two types :

• Channel Voice messages (&80 - &EF) allow control of devices dependant on what MIDI channel they are set to (ie their base channel). That is, they allow control of individual voices.

• Channel Mode messages (a subset of &Bn) are sent on a device's base channel, and are used to specify how a device should respond to Voice messages.

• System Exclusive messages (&F0) are variable length messages. There is possibly more complexity in the various messages provided by this single status byte than by the rest of the MIDI specification.
  It has become the main route for expansion of the standard. It provides for manufacturer defined, device-specific messages, and any other messages involving larger amounts of data (ie blocks of data rather than the odd byte or two) than allowed for in all other messages.

• System Common messages (&F1 - &F7) are involved with various system setup type operations, including sequencer (song) control and timing, and an instruction for a sound generator to ensure that it is in tune.

• System Real Time messages (&F8 - &FF) are all single byte commands involved primarily with the control and timing of sequencer (song) playback.

Notes :
nnnn	0-15 = MIDI channel 1-16
sss	1-7
ttt	0-7

System Real Time messages (0xF8 - 0xFF) are all single byte messages, and so running status is not applicable. Also, they can be interleaved within other messages without affecting running status in any way.

System Common and System Exclusive messages (0xF0 - 0xF7), on the other hand, cancel any running status, so any message following one of these messages must contain a status byte. As with System Real Time messages, running status is not applicable to System Common and System Exclusive messages, so these messages must always contain a status byte.

Eg. to play the C Major chord based on middle C :

Without running status :

0x90 0x3C 0x7F	Note On for C4, max velocity
0x90 0x40 0x7F	Note On for E4, max velocity
0x90 0x43 0x7F	Note On for G4, max velocity

With running status, the second and third status bytes are omitted :

0x90 0x3C 0x7F	Note On for C4, max velocity
0x40 0x7F	Note On for E4, max velocity
0x43 0x7F	Note On for G4, max velocity

Both approaches are valid, and so either may be used.

To be able to cope with running status, a receiving device should always remember the last status byte that it received (except for System messages), and if it doesn't receive a status byte when expected (on subsequent messages), it should assume that it's dealing with a running status situation. Apart from System Real Time messages, new status bytes will always force a receiver to adopt that new status, even if the previous message was incomplete.

A device that generates MIDI messages should always remember the last status byte that it sent (except for System Real Time messages), and if it needs to send another message with the same status (Channel messages only, not System messages), the status byte may be omitted.

Running status is the reasoning behind the velocity = 0 variant of the Note On message (which acts as a Note Off).

Eg. to play the same C Major chord as above (though also turning it off this time) :

Without running status :

0x90 0x3C 0x7F	Note On for C4, max velocity
0x90 0x40 0x7F	Note On for E4, max velocity
0x90 0x43 0x7F	Note On for G4, max velocity
. . . . . . .	Wait for duration of the chord ...
0x80 0x3C 0x3F	Note Off for C4, middle release velocity
0x80 0x40 0x3F	Note Off for E4, middle release velocity
0x80 0x43 0x3F	Note Off for G4, middle release velocity

With running status, and using Note On with velocity = 0, to act as Note Offs :

0x90 0x3C 0x7F	Note On for C4, max velocity
0x40 0x7F	Note On for E4, max velocity
0x43 0x7F	Note On for G4, max velocity
. . . . . . .	Wait for duration of the chord ...
0x3C 0x00	Note Off for C4, no release velocity information
0x40 0x00	Note Off for E4, no release velocity information
0x43 0x00	Note Off for G4, no release velocity information

Three of these messages specify a MIDI note number : 0 - 127 (C-2 - G8), with middle C being note number 60. The standard 5 octave synthesiser keyboard range is 36 - 96, whereas the 88-note piano keyboard range is 21 - 108.

8n : Note Off

3 bytes	1000nnnn , 0kkkkkkk , 0vvvvvvv
1000nnnn	Note Off status byte;   nnnn (0-15) = MIDI channel 1-16
kkkkkkk	Note number (0-127)
vvvvvvv	Key Off (release) velocity (0-127);   Defaults to 64 in the absence of velocity sensors

9n : Note On

3 bytes	1001nnnn , 0kkkkkkk , 0vvvvvvv
1001nnnn	Note On status byte;   nnnn (0-15) = MIDI channel 1-16
kkkkkkk	Note number (0-127)
vvvvvvv	Key On (attack) velocity (1-127, soft-loud);   0 = Note Off; Defaults to 64 in the absence of velocity sensors

An : Polyphonic Key Pressure (Aftertouch)

3 bytes	1010nnnn , 0kkkkkkk , 0vvvvvvv
1010nnnn	Polyphonic Key Pressure status byte;   nnnn (0-15) = MIDI channel 1-16
kkkkkkk	Note number (0-127)
vvvvvvv	Pressure value (0-127)

Bn : Controller

3 bytes	1011nnnn , 0ccccccc , 0vvvvvvv
1011nnnn	Controller change status byte;   nnnn (0-15) = MIDI channel 1-16
ccccccc	Controller number (0-119);   See below. Values 120-127 are reserved for Channel Mode messages;   See below
vvvvvvv	Controller value (0-127);   For switch controllers : 0 = Off, 127 = On

Cn : Program Change

2 bytes	1100nnnn , 0ppppppp
1100nnnn	Program Change status byte;   nnnn (0-15) = MIDI channel 1-16
ppppppp	Program number (0-127)

Dn : Channel Pressure (Aftertouch)

2 bytes	1101nnnn , 0vvvvvvv
1101nnnn	Channel Pressure status byte;   nnnn (0-15) = MIDI channel 1-16
vvvvvvv	Pressure value (0-127)

En : Pitch Bend

3 bytes	1110nnnn , 0vvvvvvv , 0hhhhhhh
1110nnnn	Pitch Bend change status byte;   nnnn (0-15) = MIDI channel 1-16
vvvvvvv	Pitch Bend LSB value (0-127)
hhhhhhh	Pitch Bend MSB value (0-127)

0-63	High resolution continuous controllers (0-31 = MSB; 32-63 = LSB)
64-69	Switches
70-119	Low resolution continuous controllers
120-127	Channel Mode messages

Note that for switches, the second data byte (0vvvvvvv) is either 0 (Off) or 127 (On), and that for high and low resolution continuous controllers, the second data byte takes the range 0-127.

The high resolution continuous controllers are divided into MSB and LSB values, providing a maximum of 14-bit resolution. If only 7-bit resolution is needed for a specific controller, only the MSB is used - it is not necessary to send the LSB. If the full resolution is required, then the MSB should be sent first, followed by the LSB. If only the LSB has changed in value, the LSB may be sent without re-sending the MSB.

The controller numbers missing from the following list (3, 9, 14, 15, 20-31, 35, 41, 46, 47, 52-63, 85-90 and 102-119) are currently undefined.

High resolution continuous controllers (MSB)
0	Bank Select   (Detail)
1	Modulation Wheel
2	Breath Controller
4	Foot Controller
5	Portamento Time
6	Data Entry
7	Channel Volume
8	Balance
10	Pan
11	Expression Controller
12	Effect Control 1
13	Effect Control 2
16	Gen Purpose Controller 1
17	Gen Purpose Controller 2
18	Gen Purpose Controller 3
19	Gen Purpose Controller 4
High resolution continuous controllers (LSB)
32	Bank Select
33	Modulation Wheel
34	Breath Controller
36	Foot Controller
37	Portamento Time
38	Data Entry
39	Channel Volume
40	Balance
42	Pan
43	Expression Controller
44	Effect Control 1
45	Effect Control 2
48	General Purpose Controller 1
49	General Purpose Controller 2
50	General Purpose Controller 3
51	General Purpose Controller 4
Switches
64	Sustain On/Off
65	Portamento On/Off
66	Sostenuto On/Off
67	Soft Pedal On/Off
68	Legato On/Off
69	Hold 2 On/Off
Low resolution continuous controllers
70	Sound Controller 1   (TG: Sound Variation;   FX: Exciter On/Off)
71	Sound Controller 2   (TG: Harmonic Content;   FX: Compressor On/Off)
72	Sound Controller 3   (TG: Release Time;   FX: Distortion On/Off)
73	Sound Controller 4   (TG: Attack Time;   FX: EQ On/Off)
74	Sound Controller 5   (TG: Brightness;   FX: Expander On/Off)
75	Sound Controller 6   (TG: Undefined;   FX: Reverb On/Off)
76	Sound Controller 7   (TG: Undefined;   FX: Delay On/Off)
77	Sound Controller 8   (TG: Undefined;   FX: Pitch Transpose On/Off)
78	Sound Controller 9   (TG: Undefined;   FX: Flange/Chorus On/Off)
79	Sound Controller 10   (TG: Undefined;   FX: Special Effects On/Off)
80	General Purpose Controller 5
81	General Purpose Controller 6
82	General Purpose Controller 7
83	General Purpose Controller 8
84	Portamento Control (PTC)   (0vvvvvvv is the source Note number)   (Detail)
91	Effects 1 (Ext. Effects Depth)
92	Effects 2 (Tremelo Depth)
93	Effects 3 (Chorus Depth)
94	Effects 4 (Celeste Depth)
95	Effects 5 (Phaser Depth)
96	Data Increment   (0vvvvvvv is n/a; use 0)
97	Data Decrement   (0vvvvvvv is n/a; use 0)
98	Non Registered Parameter Number (LSB)
99	Non Registered Parameter Number (MSB)
100	Registered Parameter Number (LSB)
101	Registered Parameter Number (MSB)
Channel Mode messages - (Detail)
120	All Sound Off
121	Reset All Controllers
122	Local Control On/Off
123	All Notes Off
124	Omni Mode Off (also causes ANO)
125	Omni Mode On (also causes ANO)
126	Mono Mode On (Poly Off; also causes ANO)
127	Poly Mode On (Mono Off; also causes ANO)

The concept of instrument banks was introduced to get around the 128 voice limit of the Program Change message. The bank number is a 14-bit value, hence 16384 different banks are theoretically possible. The Program Change message gives access to up to 128 voices, from within the currently selected bank. There is, however, no requirement for a bank to contain the full set of 128 voices.

The Bank Select message should be transmitted as a pair, and then followed by a Program Change message :

Hex	Binary	Description
Bn , 00 , msb	1011nnnn , 00000000 , 0vvvvvvv	Bank Select, MSB
Bn , 20 , lsb	1011nnnn , 00100000 , 0vvvvvvv	Bank Select, LSB
Cn , pc	1100nnnn , 0ppppppp	Program Change

The 14-bit Bank Select value gives access to 16,384 banks using the formula :

(MSB * 128) + LSB + 1

	MSB	LSB	Bank number
	00	00	1
	00	7F	128
	01	00	129
	7F	7F	16,384

When a Note On message is received after a PTC message, the voice's pitch glides from the key number specified in the PTC message to the new Note On's pitch at the rate set by Controller 5 (Portamento Time), ignoring the current status of Controller 65 (Portamento On/Off).

A PTC message only affects the next Note On received on the relevant MIDI channel.

When in Poly mode, receiving a PTC message does not affect the pitch of any currently playing notes (whether in their sustain or release phase).

When in Mono mode, or if Controller 68 (Legato footswitch) is On, a new overlapping note event results in an immediate pitch jump to the note number specified in the PTC message, and then a glide at the current portamento rate to the note number specified in the new Note On.

For an explanation of Mono and Poly modes see the MIDI Modes sub-section under Channel Mode Messages.

The note is turned off by a Note Off which matches the Note On key number, not the key number specified in the PTC message, irrespective of mode.

Example usage :

To perform a glide from C4 to E4 :

MIDI data	Description	Result
90 3C 40	Note On, C4	C4 On
B0 54 3C	PTC from C4	No audible change
90 40 40	Note On, E4	Glide from C4 to E4
80 3C 40	Note Off, C4	No audible change
80 40 40	Note Off, E4	E4 Off

Their use involves selecting the parameter number to be edited using Controllers 98 & 99 or 100 & 101, and then adjusting the value for that parameter using Controller number 6/38, 96, or 97. Controllers 6/38 would be used to set a specific value, whereas Controllers 96 and 97 would be used to nudge the current value +1 or -1, respectively.

It is recommended that the Null Function (RPN 7F,7F) should be sent immediately after a RPN or NRPN and its value are sent.

Registered Parameter Numbers are those which have been assigned some particular function by the MIDI Manufacturers Association (MMA) and the Japan MIDI Standards Committee (JMSC). The following RPNs are currently defined :

RPN		Description
MSB	LSB
00	00	Pitch Bend Sensitivity The coarse adjustment (Controller 6) sets the number of semitones. The fine adjustment (Controller 38) sets the number of cents.
00	01	Fine Tuning
00	02	Coarse Tuning
00	03	Select Tuning Program	See also the Real Time Universal System Exclusive MIDI Tuning Standard messages.
00	04	Select Tuning Bank
7F	7F	Null Function Used to cancel a RPN or NRPN. After it is received, any additional value updates received should no longer be applied to the previously selected RPN or NRPN.

None of the Non-Registered Parameter Numbers have been assigned specific functions. They may be used for different functions by different manufacturers, and are thus manufacturer-specific.

Example usage :

To set the Pitch Bend Sensitivity on channel 'n' to +/- 7 semitones (ie +/- a fifth) :

11 bytes	Bn 64 00 65 00 06 07 64 7F 65 7F
Bn 64 00	RPN MSB = 00	Select RPN : Pitch Bend Sensitivity
65 00	RPN LSB = 00 (running status in effect)
06 07	Data Entry MSB = 07 (running status in effect)	Coarse adjustment (semitones)
64 7F	RPN MSB = 7F (running status in effect)	Null Function (Cancel RPN)
65 7F	RPN LSB = 7F (running status in effect)

Or, to set Tuning Program 'tt' on channel 'n' :

11 bytes	Bn 64 03 65 00 06 tt 64 7F 65 7F
Bn 64 03	RPN MSB = 03	Select RPN : Select Tuning Program
65 00	RPN LSB = 00 (running status in effect)
06 tt	Data Entry MSB = tt (running status in effect)	Coarse adjustment
64 7F	RPN MSB = 7F (running status in effect)	Null Function (Cancel RPN)
65 7F	RPN LSB = 7F (running status in effect)

Or, to increment the current Tuning Bank on channel 'n' :

11 bytes	Bn 64 04 65 00 60 7F 64 7F 65 7F
Bn 64 04	RPN MSB = 04	Select RPN : Select Tuning Bank
65 00	RPN LSB = 00 (running status in effect)
60 7F	Data Increment (running status in effect)	Increment
64 7F	RPN MSB = 7F (running status in effect)	Null Function (Cancel RPN)
65 7F	RPN LSB = 7F (running status in effect)

3 bytes

1011nnnn , 0ccccccc , 0vvvvvvv

ccccccc	vvvvvvv	Description
120	0	All Sound Off Causes sound generators to immediately cease all sound (no release phase involved).
121	0	Reset All Controllers Resets all controllers to their default values.
122	0 (Off) or 127 (On)	Local Control On/Off When Local Control is Off, MIDI data from a MIDI keyboard is not communicated to the keyboard's sound generators, though it is still sent out via the MIDI OUT port. MIDI data arriving at the MIDI IN port will reach the sound generators, regardless.
123	0	All Notes Off (ANO) Causes sound generators to enter the release stage of their volume envelope, and hence gently cease making sound.
124	0	Omni Mode Off  (also causes ANO)
125	0	Omni Mode On  (also causes ANO)
126	0-16	Mono Mode On (Poly Off)  (also causes ANO) vvvvvvv > 0 : Number of channels to use (Omni Off). vvvvvvv = 0 : Use all available channels (Omni On)
127	0	Poly Mode On (Mono Off)  (also causes ANO)

When Omni Mode is on, a device will respond to Channel messages on any MIDI channel, whereas when Omni Mode is off, a device will only respond to Channel messages which are on that device's base channel.

When Mono Mode is on, a device will only be able to play a single note at any time on a given MIDI channel, whereas when Poly Mode is on, a device will be able to play chords on a given channel (within that device's polyphony capability).

Note that any of these Channel Mode messages will only be responded to if they are on the receiving device's base channel. So, even when in Omni mode, a device still has a base channel as such (for the purposes of these Channel Mode messages).

Omni Mode On is a failsafe approach when connecting two devices together, as it ensures that the receiving device will respond to messages sent by the transmitting device. It is, however, totally useless in a sequencer based setup.

Multitimbral devices operate in a slightly special way. Basically each part (which has its own MIDI channel) is considered as a separate device, with each part being set to Omni Mode Off and Poly Mode On (ie independant polyphonic channels), which is ideal for use in a sequencer setup.

1 : Omni On, Poly On

Voice messages are received from all voice channels and assigned to voices polyphonically.

All voices are transmitted on the base channel.

2 : Omni On, Mono On

Voice messages are received from all voice channels, and control only one voice, monophonically.

Voice messages for one voice are transmitted on the base channel.

3 : Omni Off, Poly On

Voice messages are received on the base channel only, and assigned to voices polyphonically.

Voice messages for all voices are transmitted on the base channel.

4 : Omni Off, Mono On

Voice messages are received on voice channels <base channel> to <base channel> + nn - 1, and assigned monophonically to voices 1 to nn, respectively. The number of voices 'nn' is specified by the third byte of the Mono Mode message.

Voice messages for voices 1 to nn are transmitted on voice channels <base channel> to <base channel> + nn - 1, respectively (a single voice per channel).

Status byte		Data bytes		Description
Hex	Binary
F1	11110001	0nnndddd	--	MIDI Time Code Quarter Frame nnn = Message type; dddd = values. See also the Real Time Universal System Exclusive MTC messages.
F2	11110010	0lllllll	0hhhhhhh	Song Position Pointer lllllll = LSB (0-127);   hhhhhhh = MSB (0-127) The 14-bit value is the number of MIDI beats since the start of the song (1 beat = 6 MIDI clocks).
F3	11110011	0sssssss	--	Song Select sssssss = Song number (0-127) Select current sequence.
F4	11110100			Undefined
F5	11110101			Undefined
F6	11110110	--	--	Tune Request Upon receiving this all analogue synthesisers should initiate a self tuning operation.
F7	11110111	--	--	End of System Exclusive (EOX) Used to terminate a System Exclusive message.

To maintain timing precision, these messages can be sent at any time, even between bytes of another message. In such a situation the Real Time message is either acted upon or ignored, after which the receiving process resumes under the previous status.

Status byte		Description
Hex	Binary
F8	11111000	Timing Clock Whilst a transmitter is playing, this message is sent 24 times per quarter note.
F9	11111001	Undefined
FA	11111010	Start Start the current sequence playing, from the beginning. (This message should be followed with Timing Clocks).
FB	11111011	Continue Continue playing the current sequence from the point at which it was stopped.
FC	11111100	Stop Stop the current sequence.
FD	11111101	Undefined
FE	11111110	Active Sensing When initially sent, the receiver will expect to receive another Active Sensing message each 300ms (max), or it will assume that the connection has been terminated. At termination, the receiver will turn off all voices and return to normal (non- active sensing) operation. Use of this message is optional.
FF	11111111	System Reset Reset all receivers to their power-up status. It should be used sparingly, preferably only under manual control. In particular, it should not be sent automatically on power up, as this could lead to a situation where two devices endlessly reset each other.

Notes :
1	iiiiiii = identification ID (0-127). If the ID is 0, the following 2 bytes are used as extensions to the manufacturer ID.
2	All bytes between the System Exclusive status byte and EOX, or the next status byte, must have zero in the top bit, ie values 0-127.
3	Status or Data bytes (except System Real Time) should not be interleaved with System Exclusive data.
4	EOX, or any other status byte (except System Real Time) will terminate a System Exclusive message. However, an EOX should always be sent to specifically mark the end of a System Exclusive message.
5	3 System Exclusive ID numbers have been set aside for special purposes : 7D is reserved for non-commercial use (eg schools, research, etc.) and is not to be used on any product released to the public; 7E (Non Real Time) and 7F (Real Time) are used for extensions to the MIDI specification, and are known as Universal System Exclusive ID numbers.

Single byte IDs - American
01	Sequential Circuits
04	Moog
06	Lexicon
07	Kurzweil
0F	Ensoniq
10	Oberheim
11	Apple Computer
18	Emu
1A	ART
Single byte IDs - European
22	Synthaxe
24	Hohner
29	PPG
2B	SSL
2F	Elka / General Music
30	Dynacord
36	Cheetah
3E	Waldorf Electronics Gmbh
Single byte IDs - Japanese
40	Kawai
41	Roland
42	Korg
43	Yamaha
44	Casio
47	Akai
48	Japan Victor
4C	Sony
4E	Teac Corporation
51	Fostex
Multi byte IDs - American   (see note 1 above)
00 00 07	Digital Music Corporation
00 00 0E	Alesis
00 00 15	KAT
00 00 16	Opcode
00 00 1A	Allen & Heath Brenell
00 00 1B	Peavey Electronics
00 00 1C	360 Systems
00 00 20	Axxes

The generalised format for both is as follows :

F0 <ID number> <Device ID> <Sub ID#1> <Sub ID#2> . . . . F7

From one to sixteen virtual devices may be accessed at each Device ID by use of the normal MIDI channel numbers, within the capabilities of the device.

The Non-Commercial Universal System Exclusive ID (7D) is not detailed here.

Sub ID#1