User Manual

81
APPENDIX
B Time Code Basics
OVERVIEW
What Is synchronization?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
What is SMPTE? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Two forms of time code: LTC versus VITC . . . . . . . . . . . . . . . . . . . . . 82
What is LTC? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
What is VITC? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
The benefits of VITC over LTC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Should I use LTC or VITC? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Frame rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
What is drop frame? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Why does drop frame exist?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Should I use drop frame? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
How does synchronization work? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
How does a MOTU synchronizer work?. . . . . . . . . . . . . . . . . . . . . . . 86
What is MIDI Time Code? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Locking a MOTU interface to time code . . . . . . . . . . . . . . . . . . . . . . 86
WHAT IS SYNCHRONIZATION?
Synchronization is the occurrence of two or more events at
exactly the same point in time. In regard to SMPTE and
MIDI, it is the process of making MIDI devices, such as a
MIDI sequencer, precisely follow one another as they play
back. For example, when a tape deck plays, the sequencer
plays right along with it. When the tape fast forwards to a
new location and begins to play, the sequencer will jump
ahead to precisely the same location and begin playing,
too. Synchronization allows you to freely move about in a
piece of music without ever losing the “lockup” between
the tape and the sequencer.
Without synchronization, devices with independent time
bases, no matter how precisely they keep time, will
inevitably drift apart from one another over time.
WHAT IS SMPTE?
The word SMPTE is an acronym for the Society of Motion
Picture and Television Engineers. In the mid 1970’s, the
society established a timing standard, called SMPTE time
code, that is now an international standard. SMPTE time
code, commonly referred to as just “SMPTE”, was
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