Imposing delay on a video signal, Pre-selector to a production switcher, Feeding on-set monitors in a live environment – Ensemble Designs BrightEye NXT 410 Clean HDMI Router User Manual
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BrightEye NXT 410/415/430 Compact Router Installation, Configuration and Operations Guide
Imposing Delay on a Video Signal
A video frame sync imposes delay on a video signal passing through it in order to align that input to
the user adjusted output timing. The amount of delay is a function of the difference in timing between
the incoming video and the output of the frame sync. The frame sync can only add delay to the video
in order to make up that difference, and the amount will change automatically in accordance with the
timing of the input signal.
If the input signal is one line early compared to the output, the frame sync will add only one line of
delay. But if the incoming video is just one line late, the frame sync will add nearly an entire frame (less
one line) to bring the signal into time. If the input is asynchronous, its timing will be changing (drifting)
continuously. In that case, the delay imposed by the frame sync will vary continuously between (near)
zero and one frame.
Pre-Selector to a Production Switcher
When a Clean Switch is being used as a pre-selector to a production switcher, the Clean Switch
output timing must fall within the input auto-time window of the switcher. In general, this will be
accomplished by setting the Clean Switch H and V parameters to zero.
Feeding On-Set Monitors in a Live Environment
If the Clean Switch is feeding on-set monitors in a live environment from sources also used on
the production switcher, it is generally desirable to minimize the delay on those monitors. This is
accomplished by setting the Vertical timing of the Clean Switch to a small positive value. Setting this
parameter to +4 lines will typically guarantee that the sources (which have near zero timing) will only
experience 2 or 3 lines of delay. Since most production switchers have a forward delay of 1, 2, or 3 lines,
a setting of +4 lines on the Clean Switch will also allow the switcher output to be used with minimum
delay.