MIDI Machine Control Use MIDI Machine Control (MMC) to control the basic transport functions of another device that supports it. Enter the device's Master ID number along with any pre-roll delay in frames (this is useful if you have an analog tape deck that has to roll before sync starts). You can set a fixed minimum time between MMC commands in miliseconds for devices that have slower response times. If your device will not support 'MMC Event' commands, uncheck the box. Check with your device's manual for more info on 'MMC Event' support.