Optional video source selections for the Program and Preview rows include all external (Camera and Network) inputs, including video router sources; internal sources (Media Players and Buffers); and also the output from all of TriCaster’s M/Es, represented on the Switcher rows by buttons labeled M/E 1- (4 or 8, by model) – see Chapter 14, Mix/Effect (M/E) Tools).
The PGM (Program) row selection determines the dominant video stream of the Background (BKGD) video layer – the bottom-most layer of the composition sent to the Program output.
Other sources may be mixed into the Background layer at times, as you apply LiveMatte, or see portions of an incoming Preview row video source during a transition.
Normally, the Preview row selection determines which source is queued up for display in the Background layer by the next (BKGD) Take or Transition operation.
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