Supporting Overlay Capabilities, Using VCKernel.lib
Kernel-mode video capture drivers support a device's overlay capabilities by providing a set of functions that VCKernel.lib can call in response to requests from a user-mode driver. If the hardware supports overlay capabilities, the driver must provide the following set of functions:
Enables overlay.
Returns overlay capabilities.
Sets overlay display rectangles.
Sets the overlay offset rectangle that is used for panning.
Returns the overlay area's current key color.
Sets the overlay area's key color to a palette index number.
Sets the overlay area's key color to an RGB value.