ABSTRACT
It isn’t always necessary for a MIDI device to transmit or receive every type of MIDI message defined by the MIDI specification, because certain messages might not relate to the device’s function. For example, a synth module is only required to respond to Note On or Note Off messages. Because the device does not have a built-in keyboard, there’s no need to transmit these messages. Other devices might limit certain MIDI messages due to factors such as design limitations or cost effectiveness. For example, no amount of keyboard banging on a velocity-sensitive keyboard controller will vary the output volume on a synth that does not respond to velocity messages.
