Grass Valley 1200 Operation Manual - Manual (Page 21)

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Concepts You’ll Need to Know
Concepts You’ll Need to Know
There are a few basic concepts that you should know before you
begin setting up and operating the switcher. These concepts are
presented on the following pages.
Delegation
Some switcher functions, when selected, automatically activate
related subpanels or functions. This is called
delegation . For
example, when you press the [Key 1] button in the Transition
subpanel, the Keyer subpanel delegates to control Keyer 1.
Related functions delegate in logical ways, making operation
easier because fewer button pushes are required.
Sometimes, even with the help of automatic delegation, you must
still delegate a function manually. If a subpanel or function
doesn’t respond when you operate it, check that it is delegated to
the function you are trying to control.
Crosspoint Bus
A crosspoint bus consists of a group of switches called crosspoints ,
each with a different video or key input and a common output
called a
bus . The switches allow you to select an input for
connecting to the output. The outputs of the various buses feed
the switcher’s effects and transition circuits.
There are a number of buses in the Model 1200, including the
PGM (Program) and PST (Preset) background buses, the Key
buses, and the Aux (auxiliary) buses. The background buses feed
the video mixers, allowing you to select background sources and
do transitions between them. The key buses feed the keyers,
allowing you to set up keys, which are also fed to the mixers for
keying over the background. Lastly, the aux buses select signals
and send them directly to a switcher output for feeding external
devices, such as digital picture manipulators; this makes the same
inputs that are available to the switcher also available to the
external devices.