04-Control+Messages


 * CONTROL MESSAGES**

//Fig 9 Example of Key being pressed on Keyboard (Note On/Off)//

//Fig 10 Max program to break down MIDI signal//

The above figure represents the Max/Msp program used to analyse MIDI data sent from the controller. The MIDI IN object receives messages from a MIDI controller and sends them to the MIDI-parse object. The MIDI-parse object then seperates the messages so that they can be examined or manipulated individually. We will use elements of this patch to explain the individual messages below.



//Fig 11 Max program to break down midi signal for a note-on message//

The MAX/MSP patch above shows the pitch and velocity of a note played on the MIDI controller keyboard. The first value, 60, is the MIDI value of the note middle C and the second value, 58, is the velocity of the key press, which translates to the loudness of the note. The keyboard interprets how fast the key is depressed which is similar to how hard it was hit, which is how MIDI decides how loud the note should be played.



//Fig 12 Polyphonic Aftertouch.//

The Polyphonic key pressure function allows a more realistic playing of notes. It adds vibrato to a note while it is still pressed down. As with the previous message this can be broken down into two values, the key pressed and the value of the Aftertouch, in this example the key pressed is MIDI note number 50 and the value of the Aftertouch is 111.


 * Control/Mode Change**

//Fig 13 control change//

The control change message gives the value of the controller whose value is being changed, in this instance controller 91, and the value to which it is being changed, 81. Different functions can be assigned to each controller.


 * Program Change**

//Fig 14 Output from program change message//

The program change message tells the MAX/MSP patch what GM voicing should be implemented. In this case no. 55 is Synth Voice.

//Fig 15 Output from pitch bend wheel//
 * Pitch Bend**

//Fig 16 Pitch bend wheel//

The Pitch bend function, as you’ve probably guessed, alters the pitch of a note up or down. As seen from the three shots of the MAX/MSP patch above, the initial value is 64, which allows the dial to decrease in value to 0, and increase in value to 127.

//Fig 17 Channel Aftertouch//
 * Channel Aftertouch**

The Channel Aftertouch message behaves in much the same way as the Polyphonic Aftertouch but creates the vibrato effect across all keys pressed on one channel at the same time. This function serves to minimize the amount of data sent and as such reduces the potential for latency. This is not a common function on many MIDI devices. The value is equal to 72.


 * Channel Change Message**

The last message from the MIDI-parse patch is the MIDI channel message, which tells the controller which of the channels 1-16 the messages it is sending should be transmitted on, in this case the messages are being sent on channel 10