MultiView
MultiView composites several video streams onto one display. It is built from two objects: a layout, which sets the size and position of each window, and a configuration, which maps a source to each window and acts as a virtual source device. A layout is reusable across many configurations.
The mtv command manages and routes configurations; the layout command manages layouts.
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DisplayNet Manager's editors are the recommended way to create and modify configurations and layouts. mtv connect then automates routing the result.