Chapter 6: Additional Synchronization Information 57
Chapter 6: Additional Synchronization
Information
Video and VITC Signals
Black Burst and House Video
Reference
A black burst signal is essentially a “position-less”
video signal. As with any “shared” video signal,
you’ll want to ensure that your video feed comes
from a properly buffered and distributed source,
such as a video distribution amplifier, or the house
video reference/black burst output of another de-
vice in the chain.
Resolving to video instead of house video
reference (black burst)
There are several reasons why you would resolve a
SYNC HD to a video signal rather than house syn-
chronization.
When House Video Reference is Unavailable
Re-
solve to a video signal whenever you are synchro-
nizing Pro Tools (or other device) to video, and
you either:
• Do not have a house video reference, or
• Your setup includes equipment that lacks house
video reference input and synchronization capa-
bility (including consumer grade VCR, or some
entry-level computer-based editing systems).
Simple Setups
In a modest setting with one or two
VTRs, Pro Tools, and a SYNC HD, using the
video signal as the clock reference is often satisfac-
tory. In these situations, proper synchronization
can be achieved using the video signal as clock ref-
erence.
Why VITC is Unavailable for Clock Reference
VITC itself does not provide clock information di-
rectly as part of its timecode information, only po-
sitional information. However, since VITC is al-
ways embedded into a video signal, that video
signal can be used as a clock reference by selecting
Video Input as the clock reference (or Video Ref if
your facility has a house video reference).
VITC Timing Rule
The following rule is in effect whenever you are
generating or regenerating VITC.
Inserted VITC should be monotonic, regardless
of whether it is being regenerated or generated.
By monotonic, it is meant that the VITC should be
smoothly ascending or descending, with no re-
peated or skipped frame addresses. In order to
achieve monotonicity, the external positional ref-
erence (while regenerating) or the clock source (in
Generator Preset Mode) must be synchronous with
the video signal onto which the VITC is being in-
serted.
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