User guide

APPENDIX B: TIME CODE BASICS
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You can actually see VITC in the vertical blanking segment
portion of a video picture by adjusting the vertical hold on
a video screen. The 90-bit binary VITC signal appears as a
series of white dots in the black strip between the top and
bottom of the picture.
VITC is part of the video signal; it does not have its own
“track” on the video tape. It is therefore not possible to
stripe VITC by itself onto video tape. VITC can only be
recorded at the same time as the video picture.
THE BENEFITS OF VITC OVER LTC
Of the two forms of SMPTE time code, LTC has become
much more widely used as a synchronization standard in
the audio production industry because VITC
synchronizers in the past have been extremely expensive.
So, the term SMPTE or SMPTE time code has become a
common expression for LTC in recording studios, post-
production houses, MIDI hardware and software
manuals, and so on.
The primary advantage that VITC has over LTC is that
synchronization can be achieved at very slow tape speeds–
–even when shuttling the video tape backwards or
forwards one frame at a time. VITC allows for this because
it is part of the video signal, which is continuously scanned
by the VTR’s rotating heads even when the tape is stopped.
LTC cannot be read at slow tape speeds because it is an
audio signal in one of the audio tracks, which can only be
read when the tape is moving at a constant speed.
Another benefit of VITC is that it does not eat up any audio
tracks.
SHOULD I USE LTC OR VITC?
Since VITC only works with video, you must use LTC for
synchronizing a multi-track tape deck. But don’t fret: LTC
is affordable and more than adequate for tape synchroni-
zation.
FRAME RATES
In either form (LTC or VITC), SMPTE time code has
several basic formats for counting frames per second (fps):
23.976, 24, 25, 29.97 non-drop, 29.97 drop-frame, 30 and
!USB Interfaces Manual Book Page 83 Tuesday, August 16, 2011 11:21 AM