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appendix a
Additional Synchronization Information
Video and VITC Signals
Black Burst and House Video Reference
A black burst signal is essentially a “positionless” 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 device in the chain.
Resolving to video instead of house video
reference (black burst)
There are several reasons why you would resolve
SYNC I/O to a video signal rather than house
synchronization.
When House Video Reference is Unavailable Resolve to a video signal whenever you are synchronizing 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 capability (including consumer grade
VCR, or some entry-level PC-based editing
systems).
Simple Setups In a modest setting with one or
two VTRs, Pro Tools, and SYNC I/O, using the
video signal as the clock reference is often satisfactory. In these situations, proper synchronization can be achieved using the video signal as
clock reference.
Why VITC is Unavailable for Clock Reference
VITC itself does not provide clock information
directly as part of its time code information,
only positional information. However, since
VITC is always 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 In 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
repeated or skipped frame addresses. In order to
achieve monotonicity, the external positional
reference (while regenerating) or the clock
source (in Generator Preset Mode) must be synchronous with the video signal onto which the
VITC is being inserted.
Appendix A: Additional Synchronization Information
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