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When you assign a hardware control using the Learn button, MainStage determines the
type of MIDI message the control sends when you move it, and the range of values the
control is capable of sending. When you map the screen control to a channel strip
parameter or an action, MainStage converts (or “maps”) the range of values sent by the
hardware control to the optimal range of values usable by the parameter.
For example, many faders, knobs, and other MIDI controls send a range of numeric values
between 0 and 127. You could map a hardware knob with this range of values to control
the frequency parameter of an EQ effect, which has a range of usable values between
20 Hz and 20 kHz. When you map the screen control for the knob to the EQ frequency
parameter, MainStage converts the values sent by the hardware knob to be distributed
between the minimum (20 Hz) and maximum (20 kHz) values for the parameter.
Assigning Knobs
MIDI controllers can have different types of knobs or rotary controllers. Knobs can be
either absolute controllers, which send a fixed value determined by the knob’s position
or can be relative controllers, which increment or decrement the previous value regardless
of their exact position. Knobs can either have a fixed range of movement, or be continuous
(sometimes called endless rotary encoders).
When you assign a knob screen control using the Learn button, MainStage attempts to
determine which type of knob or rotary control on your hardware is sending the MIDI
message and sets the value in the Type pop-up menu in the Screen Control Inspector to
the correct value. For absolute controllers, the correct value is Absolute; for relative
controllers, the correct value can be either Relative (2’s complement) or Relative (Sign
magnitude), depending on the type of relative controller. In most cases, there is no need
to change the default values unless you intend to use the knob for a specific, non-standard
purpose.
When you assign a knob screen control, be sure Absolute is chosen from the Type pop-up
menu if the hardware controller is an absolute rotary controller, or one of the Relative
values is chosen if the hardware controller is a continuous rotary encoder. Moving the
knob through its full range of motion helps ensure that MainStage correctly determines
the type of knob you are assigning.
Assigning Buttons
MIDI controllers can have different types of buttons. Some buttons send a single value
each time you press them, while others alternate between two values when pressed.
Other buttons can send separate values when they are pressed and released (this type
of button is called a momentary or temporary button).
115Chapter 7 Working in Layout Mode