MIDI Channel Mode Messages

For all MIDI Channel Mode Messages, the message channel 'n' must be the Basic Channel of the MIDI device, or the message will be ignored.

MIDI Channel Mode Messages
Status
Byte 		Data
Bytes 		Message Description
Bn 78 00 All Sound Off Turn off all sound, including envelopes of notes still sounding, and reverb-effects (if applicable).
 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
Status
Byte 		Data
Bytes 		Message Description
Bn 79 00 Reset All Controllers Reset all controllers to their 'default' positions, including all continuous and switch controllers, pitch-bend, and aftertouch effects.

Each controller should be returned to a suitable initial condition for that controller. For example, pitch-bend should be returned to it 'center' position.

This message must be ignored if Omni is On (Modes 1 and 2).

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
Status
Byte 		Data
Bytes 		Message Description
Bn 7A xx Local Control Disconnect (or reconnect) the keyboard and the sound generator in a MIDI synthesizer.

The keyboard should continue to send messages via the MIDI-out port, and the sound-generation circuitry should continue to respond to message received via the MIDI-in port, regardless of this switch.

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
 xx 00, 7F If 00, disconnect the local keyboard from the sound generating functions of a synthesizer.
If 7F, reconnect the local keyboard to the sound-generator. 		00=Off
7F=On (default)
Status
Byte 		Data
Bytes 		Message Description
Bn 7B 00 All Notes Off Turn off all notes which for which a note-on MIDI message has been received. (note 1)

This only applies to notes turned on via MIDI, and not to notes turned on via pressing keys on a local keyboard.

This message must be ignored if Omni is On (Modes 1 and 2).

In Mode 4 (as well as Mode 3), this message must only affect the MIDI Channel on which it is received.

If a hold-pedal is 'on' (controller 0x40), then this message should not be acted on until the hold-pedal is released.

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
Status
Byte 		Data
Bytes 		Message Description
Bn 7C 00 Omni Mode Off The receiver should respond only to Channel Voice messages which is receives on it's Basic Channel. (note 2)

This puts the receiving MIDI device into Channel Mode 3 or 4, depending on the current state of the Mono/Poly switch. (note 3)

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
Status
Byte 		Data
Bytes 		Message Description
Bn 7D 00 Omni Mode On The receiver should respond to Channel Voice messages which is receives on any MIDI channel. (note 2)

This puts the receiving MIDI device into Channel Mode 1 or 2, depending on the current state of the Mono/Poly switch. (note 3)

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
Status
Byte 		Data
Bytes 		Message Description
Bn 7E m Mono Mode On Puts the receiver into monophonic mode. (note 2)

This puts the receiving MIDI device into Channel Mode 2 or 4, depending on the state of the Omni switch. (note 3)

While Omni is on, the m=1 is used.

If n+m-1 > Ch.16 there is no wrap-around to Ch.1. Only channels n...16 are used

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1
 m 00-10 Number of MIDI Channels to use when in Mode 4.
This parameter has no effect in Mode 2. 		00 = use n...16
01 = use 1 channel
0x10 = use 16 channels (provided n=0)
Status
Byte 		Data
Bytes 		Message Description
Bn 7F 00 Poly Mode On Puts the receiver into polyphonic mode. (note 2)

This puts the receiving MIDI device into Channel Mode 1 or 3, depending on the state of the Omni switch. (note 3)

 Value Range Description
 n 0-F MIDI Channel 0 = Ch 1

Footnotes

Note 1
There no requirement that a MIDI device support the All-Notes-Off message. A MIDI transmitter must still send individual note-off messages for each note which has been turned on, regardless of the fact that it has sent an All-Notes-Off message.
Note 2
There is an implicit 'All-Notes-Off' function associated with a change of the Channel Mode. That is, when changing Channel Mode, the receiver should turn off all notes turned on via MIDI messages while in the old mode.
This excludes notes turned on via the 'local' keyboard (if applicable).

Although it is not stated explicitly in the specification, I think this:

  • includes notes on all channels n...n+m-1 while in Mode 4.
  • applies even if the Omni was or is 'On' (unlike the All-Notes-Off message).

To quote the specification (section 2, p20):
"Messages 123 [7B] to 127 [7F] ... will turn off all voices controlled by the assigned Basic Channel".
and (section 2, A-4):
"When a receiver is switching between Omni On/Off and Poly or Mono modes, all notes should be turned off. This is to avoid any unexpected behavior when the instrument's mode is switched."

Note 3
There is no requirement on a MIDI device to support all 4 possible Channel Modes.
If a Mode Change message is ignored (due to a particular mode being absent), there is no requirement to perform the All-Notes-Off function.

 

 
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