Reads a specific MIDI controller message from the MIDI input device and returns its value.
midiin_ctrl({ctrlnum})
Read the value of MIDI controller 7 (Volume control)
midiin_ctrl(7); // returns the current value of the Volume controller
midi_note_on midi_note_off midi_ctrl midi_prog midi_play midi_stop midi_is_playing
midiin_channel midiin_prog midiin_note midiin_ctrl