NewTek Talkshow VS-100, User Manual

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APPENDIX B GENLOCKING
TalkShow’s Genlock feature allows it to ‘lock’ its video output
to a reference video signal supplied to its Genlock input
connector. This synchronizes SDI output to other external
equipment locked to the same reference.
Genlocking is not a requirement, but it is very beneficial, and
you should definitely use it if you have the capability.
TalkShow
®
can provide output from up to four sources.
Miniscule local timing differences between these may force
tiny delays during switching operations, which can also
contribute to overall latency. Thus, serving i) TalkShow’s
Genlock input and ii) other video devices in the chain with a
single reference is the best approach.
SECTION 4.5
VERTICAL POSITION, HORIZONTAL
POSITION AND PHASE
Locking all devices to house sync is important, but this alone
does not actually ensure a perfect downstream match.
Consider an army marching along: each step the soldiers take occurs at precisely the same moment,
so we could say their timing is synchronized. Even so, problems result if one soldier leads with the
left foot while everyone else is on the right. Or perhaps everyone is evenly spaced and perfectly
aligned but for one misfit who ‘tailgates’ the soldier ahead of him and keeps stepping on his heels.
FIGURE 35
This is essentially why TalkShow provides several adjustments in its Genlock section. The
Horizontal and Vertical Position settings pin the image in the proper space in the frame, and in doing
so could be likened to making sure each marching soldier is in position relative to his fellows (as
Hint: The term “genlock” refers
to “generator locking”.
Professional video devices often
provide a “genlock input”, which
allows an external reference
signal (often referred to as
‘house sync’) to control its video
timing.
The output of video devices
connected in this manner is
synchronized to the reference
signal, and they are referred to
as ‘genlocked’.