This chapter provides a short summary of MIDI messages. For full details you
should refer to the MIDI Specification document from the Midi User Group. A
particular device’s response to messages is given by its MIDI implementation chart.
Status Bytes and Data Bytes
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Each MIDI message consists of a status byte followed by an appropriate number of data bytes. Values between hex 80 to FF make up the 128 kinds of Status Byte.
Any value between 00 and 7F is a data byte. It contains information relating to a preceding status byte such as Note Number or Key Velocity.
The following table shows the various groups of MIDI messages, in which n represents the MIDI Channel Number.:-
Symbol MIDI Message Hex Value
DATA BYTES 00 to 7F
CHANNEL STATUS BYTES 80 to EF
NOF Note Off 8n
NON Note On 9n
PKP Polyphonic Key Pressure An
CCH Control Change Bn
PCH Program Change Cn
MCP Monophonic Channel Pressure Dn
PWL Pitch Wheel En
SYSTEM COMMON STATUS BYTES FO to F7
SOX Start of Exclusive F0
MTC Midi Time Code Quarter Frame F1
SPP Song Position Pointer F2
SCH Song Change F3
TRQ Tuning Request F6
EOX End of Exclusive F7
REAL TIME STATUS BYTES F8 to FF
CLK Timing Clock F8
STR Sequence Start FA
CNT Sequence Continue FB
STP Sequence Stop FC
SNS Active Sensing FE
RST System Reset FF
Hexadecimal notation is used throughout this chapter, except where single-digit value is shown without a preceding zero. For example, 03 is hex and 3 is decimal.
This chapter doesn’t Include General MIDI (GM) messages or those reserved for future use.
 
Channel Messages
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These status bytes contain a channel number in the least significant nibble. Each voice can be assigned its own number — it’s done automatically in General MIDI (GM) devices.
Although a simple instrument uses only one MIDI channel, multi-timbral devices can use as many channels as you can assign. The lowest numbered of these channels is the Basic Channel — used for information that’s not associated with a particular voice.
Channel Voice Messages
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Channel Voice Messages control an
instrument’s voices — only devices
or voices assigned to a matching MIDI
channel will respond.
Running status reduces the number of bytes transmitted and can be crucial for musical timing! In the process a string of data bytes is allowed to follow a single status byte without any other status bytes being sent. For example, a Note On status byte can be followed by any number of ‘note on’ or ‘note off’ data bytes — the latter are ‘note on’ bytes with the velocity (the pressure applied to a key) set to zero.
All voice messages, except Monophonic Channel Pressure, use two data bytes. The first specifies the note number and the second indicates the velocity.
The Channel Voice messages are:-
80 to 8F: Note Off (NOF)
Indicates a key (note) has been released. The second data byte indicates the speed of release or off velocity, sometimes unused and set to hex 40. Messages are in the form:-
8n, kk, vv
kk = note number:
34 = middle C (C3)
n = MIDI channel between 00 and 15, representing channels 1 to 16
vv = off velocity, usually using a logarithmic scale:
00 = off
01 = 'ppp'
34 = 'mp'
40 = mid position or no sensor
46 = 'mf'
FF = 'fff'
90 to 9F: Note On with running status (NON)
Indicates a key has been pressed. The second data byte is the applied pressure or on velocity.
9n, kk, vv, kk, vv, - - -
n, kk: as Note Off
vv = on velocity or Note Off:
00 = note off (using Running Status)
01 to FF = on velocity (see above)
A0 to AF: Polyphonic Key Pressure or After Touch (PKP)
Indicates the pressure applied to an individual key. This is rarely used — see Monophonic Channel Pressure below.
An, kk, vv
n, kk, vv: as Note Off (see above)
D0 to DF: Monophonic Channel Pressure or After Touch (MCP)
Indicates pressure has been applied to the keyboard — it’s often used in preference to Polyphonic Key Pressure (see above) and isn’t specific to any particular key being pressed.
Dn, vv
n, vv: as Note Off (see above)
Channel Mode Messages
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Channel Mode Messages tell an device
how to respond to Voice Messages —
they’re sent over the instrument’s
Basic Channel.
Mode messages control parameters that are universal for a device — such as volume. Although most devices only use one Basic Channel it’s possible to use two or more — allowing a single instrument to behave as if it were several independent synthesisers.
The messages are:-
B0 to BF: Control Change with running status (CCH)
Indicates that a control or switch has moved. Two pairs of data bytes specify which continuous controller or switch has been adjusted and its setting.
The 32 14-bit controllers include breath control (1), foot pedal (4), portamento time control (5), data entry slider (6) and main volume (7). Earlier instruments often confuse controllers 4 and 7! All values are encoded using a logarithmic scale and split into a most and least significant byte (MSB and LSB). These controllers can be used in a non-standard way to operate an automated sound mixer — the maximum capacity is 64 7-bit faders (with 0.8 dB resolution) or 32 14-bit faders, plus switches.
Four 7-bit controllers are used for sustain, portamento, sostenuto and soft pedals switches. There are a further 19 7-bit controllers, data increment and decrement buttons, two 14-bit parameter controls, a controllers reset switch, a local control switch and switches to set the instrument’s Mode and to send an All Notes Off command.
Channel Modes determine how the instrument responds to channel messages. Poly Mode On deselects Mono Mode and vice versa.
For a receiver with a Basic Channel of N the responses are:
Mode Omni Messages received from
1 On Poly All channels play voices polyphonically
2 On Mono All channels play one monophonic voice
3 Off Poly Channel N plays voices polyphonically
4 Off Mono Channel N through to N+M-1 are assigned
monophonically to voices 1 to M
For a transmitter with a Basic Channel of N:
Mode Omni Messages Sent
1 On Poly All voices to channel N
2 On Mono Mono voice to channel N
3 Off Poly All voices to channel N
4 Off Mono Single voices 1 to M to channels N through to N+M-1
If a receiver can’t accept a mode it may ignore the message or switch to Mode 1. Instruments should default to Mode 1 at startup — but most don’t!
Messages are in the form:-
Bn, cc, vv, cc, vv, - - -
n = MIDI channel number
cc = controller number
(followed by vv as a controller value unless shown otherwise):
00 to 1F = MSB for 14 bit controllers 00 to 1F (0 to 31):
The following are assigned:
01 = breath controller
04 = foot controller
05 = portamento time
06 = data entry slider
07 = main volume
20 to 3F = LSB for above controllers
40 to 5F = 7-bit controllers 40 to 5F (0 to 31)
The following are assigned as switches
(vv = 00 to 3F for ‘off’, 40 to 7F for ‘on’):
7A = Local Control (vv = 00 for ‘off’, 7F for ‘on’)
7B = All Notes Off (vv = 00)
7C = Omni Mode Off/All Notes Off (vv = 00)
7D = Omni Mode On/All Notes Off (vv = 00)
7E = Mono Mode On/All Notes Off
vv = M M channels used starting with the Basic Channel
vv = 0 all available channels to be used
7F = Poly Mode On/All Notes Off (vv = 00)
C0 to CF: Program Change (PCH)
Indicates that a voice or patch has been selected.
Cn, pp
n = MIDI channel number
pp = program number
E0 to EF: Pitch Wheel (PWL)
Indicates the pitch bend controller has moved. Two data bytes are used for the 14-bit data. Sensitivity to pitch bend is determined within the receiver.
En, vv, VV
n = MIDI channel
vv, VV = pitch bend LSB, MSB
System Common Messages
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System Common Messages are sent and
received irrespective of MIDI channels.
They’re designed to be received by all
devices in a MIDI system — assuming
they can make use of them!
The System Common Messages are:-
F1: MIDI Timecode Quarter Frame Message (MTC)
At the start of a run of timecode a Full MIDI Timecode Message must be sent (see Real Time System Exclusive messages below). The MTC Quarter Frame message only indicates the current position within a run of timecode.
100 messages are sent per second, using only 7.5% of MIDI’s total bandwidth. Timecode is contained in a data byte spread over 8 messages — hence a full update only occurs on every second frame of timecode.
F1, nd
n = timecode message type
00 = frames LS nibble
01 = frames MS nibble
02 = seconds LS nibble
03 = seconds MS nibble
04 = minutes LS nibble
05 = minutes MS nibble
06 = hours LS nibble
07 = hours MS nibble
d = timecode nibbles assembled by the receiver into data bits.
For the hours count:- xyyzzzzz
yy = SMPTE timecode type:
0 = 24 frm/s
1 = 25 frm/s
2 = 30 frm/s drop-frame
3 = 30 frm/s non drop-frame
zzzzz = hours count (0 to 23)
F2: Song Position Pointer (SPP)
A count of MIDI beats elapsed as a sequencer plays its song. One beat equals 6 MIDI clocks.
F2, pp, PP
pp, PP = pointer LSB, MSB
F3: Song Change (SCH)
Selects the song to be played by a sequencer following a Real Time Start message.
F3, ss
ss = song number
F6: Tuning Request (TRQ)
This is rarely used — it doesn’t use any data bytes.
F7: End of System Exclusive (EOX)
Indicates that System Exclusive data has ended (see below). No data bytes are used.
Real Time Messages
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  Real Time Messages are sent and
received irrespective of MIDI channels
and have the highest timing priority.
They can be interposed between any
bytes, perhaps separating status bytes
from their data, or even placed in the
middle of running status information.
Real Time Messages don’t use data
bytes.
The Real Time messages are:-
F8: Timing Clock
These ‘pulses’ drive a sequencer at a rate of six clocks per MIDI beat. Each device uses a Song Position Pointer register to count these beats during a sequence.
There are 16 beats or 96 clocks per whole note. The relationship between note lengths, beats and clocks is given below:-
Note MIDI beats MIDI clocks
Semibreve (whole note) 16 96
Minim (half note) 8 48
Crotchet (quarter note) 4 24
Quaver (eighth note) 2 12
Semiquaver (sixteenth note) 1 6
FA: Sequence Start (STR)
FB: Sequence Continue (CNT)
FC: Sequence Stop (STP)
Instructions to a sequencer.
FE: Active Sensing (SNS)
This feature is optional — it silences an instrument if its MIDI cables are accidentally disconnected. Any device that receives this signal will expect another every 300 milliseconds. If they fail to appear the receiver then defaults to non-sensing mode and turns off all voices.
FF: System Reset (RST)
This restores all instruments to normal. It’s implemented by the user — not automatically at startup.
System Exclusive Messages
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  Most System Exclusive Messages
are specific to particular
equipment — the manufacturer
determines the rules. They can
contain a manufacturer’s
identification number (ID) to
match the appropriate protocol.
They are often used for voice
editing or remote control of
synthesisers.
System Exclusive information must be aimed at particular piece of equipment — this allows two identical devices to share the same MIDI circuit. Hence every instrument is given unique device ID — this often corresponds to the basic channel number.
Two special IDs are used for Universal System Exclusive messages that are available to any device — irrespective of the manufacturer!
The System Exclusive messages are:-
F0: Start of Exclusive (SOX) — Manufacturers System Exclusive
This contains a manufacturer’s ID code.
F0, ii, xx, - - - xx, F7
ii = manufacturer’s ID
The following are examples:
01 = Sequential Circuits
04 = Moog
10 = Oberheim
17 = Linn
18 = Emu
41 = Roland
42 = Korg
43 = Yamaha
44 = Casio
45 = Akai
xx = Sysex data determined by the above manufacturer
F7 = End Of System Exclusive (EOX)
F0: Start of Exclusive (SOX) — Non Real-Time Universal System Exclusive
These special messages are directed to specific devices using the device ID.
• Set Up Message
Used to send instructions to a device that uses MIDI timecode — such as a multi-track recorder or sequencer.
hh = hours and SMPTE type containing bits organised as: 0yyzzzzz
yy = SMPTE timecode type
00 = 24 frm/s
01 = 25 frm/s
02 = 30 frm/s drop-frame
03 = 30 frm/s non drop-frame
zzzzz = hours (0 to 23)
mm = minutes
ss = seconds
ff = frames
gg = fractional frames (0 to 99)
LL = 14-bit event number LSB. Set to zero if jj=00 (Special Mode)
MM = 14-bit event number MSB
Set to global command if jj=00 (Special Mode):
00 = Timecode Offset
01 = Enable Event List
02 = Disable Event List
03 = Clear
04 = System Stop
05 = Event List Request (sent by master devices to a MTC peripheral)
aa = additional info
MIDI data is sent as nibbles with LS nibble first.
For example a Note On of 93, 48, 7F is sent as 03, 09, 08, 04, 0F, 07.
If jj = 0E (Event Name in Additional Data) then ASCII data is sent
in the same form — both CR and LF codes must be sent for a new line
F7 = End Of System Exclusive (EOX)
The following Universal System Exclusive messages are concerned with the transfer of audio samples via MIDI:-
• Sample Dump Request
Used prior to the transfer of sound sample data between a controlling device and sampler. For best results MIDI circuits should be connected in both directions to create a closed loop with handshaking. After 2 seconds of waiting for any handshake signals the system defaults to open loop operation.
F0, 7E, nn, 03, ss, SS, F7
7E = ID for Non Real Time Universal
nn = device ID
03 = sub ID 1 for Sample Dump Request
ss, SS = stored sample number LSB, MSB
F7 = End of System Exclusive (EOX)
• Dump Header
This is transmitted before sending a sound sample. Where two or three data bytes are used the LSB is sent first.
F0, 7E, nn, 01, ss, SS, bb, pp, pp, PP, mm, mm, MM, xx, xx, XX, yy, yy, YY, tt, F7
7E = ID for Non Real Time Universal
nn = device ID
01 = sub ID 1 for Dump Header
ss, SS = stored sample number
bb = number of bits (8 to 28) in each sample
pp, pp, PP = sample period in nanoseconds
mm, mm, MM = sample length measured in number of sample words
xx, xx, XX = sustain loop start point in words from start of the sample
yy, yy, YY = sustain loop end in words from end of the sample
tt = loop type (00 for ‘forward’, 01 for ‘forward/backward’)
F7 = End of System Exclusive (EOX)
• Sample Dump Handshake
This indicates if a device can accept the data as defined in the Sample Dump Header.
F0, 7E, nn, mm, pp, F7
7E = ID for Non Real Time Universal
nn = device ID
mm = Handshake Mode:
7C = Wait — further handshake message to follow
7D = Cancel — device can’t accept the data
7E = Not Acknowledged (NAK) — device awaiting retransmission of a
faulty packet
7F = Acknowledged (ACK) — packet received
pp = packet number
F7 = End of System Exclusive (EOX)
• Sample Dump Packet
This is used for the process of dumping a sample. The time taken for transfer may be ten times the sample’s duration — or longer.
F0, 7E, nn, 02, pp, dd, dd, -- dd, cc, F7
7E = ID for Non Real Time Universal
nn = device ID
02 = sub ID 1 for Sample Dump Packet
pp = packet number, restarting from zero as necessary
dd = data packets each containing 120 bytes
cc = checksum of all data not including any status bytes.
F7 = End of Exclusive (EOX)
F0: Start of Exclusive (SOX) — Real-Time Universal System Exclusive
These messages contain time-related information for a device with a matching device ID.
• Full MIDI Timecode Message
This message should be sent at the beginning of a run of timecode.
F0, 7F, nn, 01, 01, hh, mm, ss, ff, F7
7F = Real Time Universal
nn = device ID (7F to select entire system)
01 = sub ID 1 for MIDI Timecode
01 = sub ID 2 for Full Timecode message
hh, mm, ss, ff = timecode as in MIDI Cueing Setup Message (see above)
F7 = End of System Exclusive (EOX)
• User Bits
These bits are usually fixed throughout a run of timecode — they’re the same as the User Bits in SMPTE timecode.
