Auto Select Key
An Auto Select Key is a key in which two video signals are required to make the key. The Alpha is used to cut the hole in the video and the fill is used to fill the hole. These signals often originate from external devices such as character generators, external still stores, or other graphics systems.
An auto select key is set up by selecting the key and video source you want to use, and adjusting the key parameters. The pairing of the video and alpha video signal is done when configuring video inputs. Refer to the Setup Manual that came with your switcher for information on setting up Auto Keys.