Analyse du protocole MIDI

Table 1: MIDI 1.0 Specification Message Summary

Status
D7----D0

Data Byte(s)
D7----D0

Description

Channel Voice Messages [nnnn = 0-15 (MIDI Channel Number 1-16)]  (voir détail chapitre Détails messages Voix et Mode)

1000nnnn

0kkkkkkk
0vvvvvvv

Note Off event. (voir détail chapitre Détails messages Notes)
This message is sent when a note is released (ended). (kkkkkkk) is the key (note) number. (vvvvvvv) is the velocity.

1001nnnn

0kkkkkkk
0vvvvvvv

Note On event.
This message is sent when a note is depressed (start). (kkkkkkk) is the key (note) number. (vvvvvvv) is the velocity.

1010nnnn

0kkkkkkk
0vvvvvvv

Polyphonic Key Pressure (Aftertouch).
This message is most often sent by pressing down on the key after it "bottoms out". (kkkkkkk) is the key (note) number. (vvvvvvv) is the pressure value.

1011nnnn

0ccccccc
0vvvvvvv

Control Change.
This message is sent when a controller value changes. Controllers include devices such as pedals and levers. Controller numbers 120-127 are reserved as "Channel Mode Messages" (below). (ccccccc) is the controller number (0-119). (vvvvvvv) is the controller value (0-127).

1100nnnn

0ppppppp

Program Change. This message sent when the patch number changes. (ppppppp) is the new program number.

1101nnnn

0vvvvvvv

Channel Pressure (After-touch). This message is most often sent by pressing down on the key after it "bottoms out". This message is different from polyphonic after-touch. Use this message to send the single greatest pressure value (of all the current depressed keys). (vvvvvvv) is the pressure value.

1110nnnn

0lllllll
0mmmmmmm

Pitch Bend Change. This message is sent to indicate a change in the pitch bender (wheel or lever, typically). The pitch bender is measured by a fourteen bit value. Center (no pitch change) is 2000H. Sensitivity is a function of the receiver, but may be set using RPN 0. (lllllll) are the least significant 7 bits. (mmmmmmm) are the most significant 7 bits.

Channel Mode Messages (See also Control Change, above) 

1011nnnn

0ccccccc
0vvvvvvv

Channel Mode Messages.
This the same code as the Control Change (above), but implements Mode control and special message by using reserved controller numbers 120-127. The commands are:

All Sound Off. When All Sound Off is received all oscillators will turn off, and their volume envelopes are set to zero as soon as possible. c = 120, v = 0: All Sound Off

Reset All Controllers. When Reset All Controllers is received, all controller values are reset to their default values. (See specific Recommended Practices for defaults).
c = 121, v = x: Value must only be zero unless otherwise allowed in a specific Recommended Practice.

Local Control. When Local Control is Off, all devices on a given channel will respond only to data received over MIDI. Played data, etc. will be ignored. Local Control On restores the functions of the normal controllers.
c = 122, v = 0: Local Control Off
c = 122, v = 127: Local Control On

All Notes Off. When an All Notes Off is received, all oscillators will turn off.
c = 123, v = 0: All Notes Off (See text for description of actual mode commands.)
c = 124, v = 0: Omni Mode Off
c = 125, v = 0: Omni Mode On
c = 126, v = M: Mono Mode On (Poly Off) where M is the number of channels (Omni Off) or 0 (Omni On)
c = 127, v = 0: Poly Mode On (Mono Off) (Note: These four messages also cause All Notes Off)

System Common Messages

11110000

0iiiiiii
[0iiiiiii
0iiiiiii]
0ddddddd
---
---
0ddddddd
11110111

System Exclusive.
This message type allows manufacturers to create their own messages (such as bulk dumps, patch parameters, and other non-spec data) and provides a mechanism for creating additional MIDI Specification messages. The Manufacturer's ID code (assigned by MMA or AMEI) is either 1 byte (0iiiiiii) or 3 bytes (0iiiiiii 0iiiiiii 0iiiiiii). Two of the 1 Byte IDs are reserved for extensions called Universal Exclusive Messages, which are not manufacturer-specific. If a device recognizes the ID code as its own (or as a supported Universal message) it will listen to the rest of the message (0ddddddd). Otherwise, the message will be ignored. (Note: Only Real-Time messages may be interleaved with a System Exclusive.)

11110001

0nnndddd

MIDI Time Code Quarter Frame.
nnn = Message Type
dddd = Values

11110010

0lllllll
0mmmmmmm

Song Position Pointer.
This is an internal 14 bit register that holds the number of MIDI beats (1 beat= six MIDI clocks) since the start of the song. l is the LSB, m the MSB.

11110011

0sssssss

Song Select. 
The Song Select specifies which sequence or song is to be played.

11110100

Undefined. (Reserved)

11110101

Undefined. (Reserved)

11110110

Tune Request. Upon receiving a Tune Request, all analog synthesizers should tune their oscillators.

11110111

End of Exclusive. Used to terminate a System Exclusive dump (see above).

System Real-Time Messages

11111000

Timing Clock. Sent 24 times per quarter note when synchronization is required (see text).

11111001

Undefined. (Reserved)

11111010

Start. Start the current sequence playing. (This message will be followed with Timing Clocks).

11111011

Continue. Continue at the point the sequence was Stopped.

11111100

Stop. Stop the current sequence.

11111101

Undefined. (Reserved)

11111110

Active Sensing. This message is intended to be sent repeatedly to tell the receiver that a connection is alive. Use of this message is optional. When initially received, the receiver will expect to receive another Active Sensing message each 300ms (max), and if it does not then 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. 

11111111

Reset. Reset all receivers in the system to power-up status. This should be used sparingly, preferably under manual control. In particular, it should not be sent on power-up.