Grass Valley Kayak HD v.6.9.3 - Manual (Page 174)

174 Kayak — User Manual
Section 5 — Kayak Menu Summaries
Figure 98. Config - GPI Functions
Config - GPO / Tally Menu
The General Purpose Interface Output/Tally menus are used to configure
the tally system. There are multiple tally calculators, three different tally
calculation methods, and user assignment of tally relays. The results of the
tally calculators are applied to the tally relays on the Video Processor frame,
and those relays control external tally lights.
Tally is recalculated and refreshed every field.
In addition, the GPO Output contact closures are used by the Kayak system
for simple trigger control of external devices.
About Tally Systems
In general, a tally system identifies which sources to the switcher contribute
to the final picture at a selected point in the video chain. The identification
is communicated by activating relays in the video frame. The method by
which the sources are determined is called the tally calculation.
The tally calculation begins at a point in the video path and then traces the
path of the signals upstream to their original video (and key) sources. The
state of the switcher affects tally. For example, tally on a true clean feed only
includes sources that contribute to the main output, but tally on a program-
mable clean feed can include sources that do not contribute to the main
output.