Apple Logic Pro X - Manual (Page 879)

Chapter 25 Preferences, project settings, and key commands 879
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Transmit MMC checkbox: Select this checkbox to allow transmission of MIDI Machine Control.
These commands are then sent whenever you operate the transport functions (Start, Stop,
Rewind, and so on) of Logic Pro.
MMC is normally used when Logic Pro is running as a slave to an external master (such as
an ADAT), and you want to control the external master’s transport functions from Logic Pro.
Logic Pro therefore acts as MMC master and MTC slave simultaneously. If you want to use the
external master’s transport controls, you don’t need to use MMC. In this situation, Logic Pro
follows the MTC master as a slave. You can also use MMC to record-enable tracks on the MMC
slave device.
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Listen to MMC Input checkbox: Select this checkbox to control Logic Pro by MMC (MIDI Machine
Control) and so-called Full Frame Messages.
Logic Pro recognizes these commands when listening to MMC Input:
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Play
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Deferred Play
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Stop
Deferred Play is a special command for mechanically slow synchronization slaves such as reel-
based tape recorders. Rather than having the machine play immediately, it is asked to reach
the desired SMPTE position before playback is started. There is no noticeable difference in the
response of Logic Pro to the Play and Deferred Play commands, as Logic Pro can start playback
at any position almost instantly.
Logic Pro ignores these messages when incoming external MTC (MIDI Time Code) commands
are detected.
Logic Pro also obeys Full Frame Messages, and sets the playhead to a new location, without
starting playback. Once again, incoming MTC data has higher priority, if conflicting information
is received.
Some synchronizers send Full Frame Messages (instead of MTC) to locate the slave device
(Logic Pro in this case) to a new position, without implicitly starting playback. This is useful
when in Slow Shuttle or Single Frame Advance mode with video machines, because the slave
device is perfectly located, without being in playback mode.