13.7 Control Change Messages
Control change messages are used to change the status of a MIDI parameter.
Kind: concept (user-guide-section) Chapter: 13 Working with MIDI Items Source: REAPER User Guide v7.70
Control change messages are used to change the status of a MIDI parameter. If using an actual MIDI device, these messages can be used to physically control the foot pedals, volume sliders, modulation wheels, and other controls on electronic instruments. Within REAPER, control change messages can simulate this effect when playing back your MIDI data thru a software synthesizer.
Controller data is used for various purposes. The different controller data streams are numbered from 0 to 127. Some of these controller numbers are industry standard. For example, controller 7 is generally used to control volume and controller 10 for panning. A control change message has two parts. The first is the control change number, which determines which parameter is to be set. The second is the desired value for that parameter. For example, first, you might send a CC #7 message to specify that you want to adjust volume. Next, you send a value that sets the actual volume level required.
A control change message can act as either an override (setting the parameter to the exact value specified), or an offset (adjusting the parameter up or down by the amount specified).