Syphon
Syphon is a macOS-only protocol and library for sharing video textures across applications.
Syphon input device
This device allows receiving a video stream directly from a Syphon-compatible input.
Simply choose the wanted input in the list, and put the output at the end of the video chain.
Syphon output device
This device allows to create a Syphon stream that other Syphon-compatible software will be able to display or modify.
Simply choose the viewport options, a rendering rate, and a name for the output. You can then use the device as input to video filters.