Digital Sound & Music: Concepts, Applications, & Science, Chapter 6, last updated 6/25/2013
44
As the name indicates, quarter frame messages are transmitted in increments of four
messages per frame. Messages are transmitted in the order listed above. Consequently, the entire
SMPTE time is completed every two frames. Let’s break down the same 01:30:35:20 time value
into quarter frame messages in hexadecimal. This time value would be broken up into eight
messages:
F1 04
(Frame LS)
F1 11
(Frame MS)
F1 23
(Seconds LS)
F1 32
(Seconds MS)
F1 4E
(Minutes LS)
F1 51
(Minutes MS)
F1 61
(Hours LS)
F1 76
(Hours MS and Frame Rate)
When synchronizing systems with MIDI Time Code, one device needs to be the master
time code generator and all other devices need to be configured to follow the time code from this
master clock. Figure 6.43 shows Logic Pro configured to synchronize to an incoming MIDI Time
Code signal. If you have a mix of devices in your system that follow LTC or MTC, you can also
put a dedicated time code device in your system that collects the time code signal in LTC or
MTC format and then relay that time code to all the devices in your system in the various
formats required, as shown in Figure 6.44.
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