Write a "video metadata" playback driver

Question

Hello! I would like to write a driver that can receive a mirror copy of the video stream provided to a video playback driver, such as an HDMI or SDI card, and my driver would analyze the frames for blackness. If a frame is 98%+ black it would make a REST API call to an Internet endpoint saying "signal loss", and if the blackness drops below that threshold then it makes another call saying "signal". (ie: a metadata only representation of the frame contents.)

Do I need to write a full KMDOD driver, of "Media" class, perhaps? Or maybe an "Indirect Display" of class "Display"? And then how do I arrange it to where this driver can "attach" itself to a graphics adapter output or another playback card's output, such as the selected device for the Program Output from an app like Adobe Premiere? Do I configure it as a "child", or can the user somehow "tie" them together?

Thanks,
Galan
(long-time developer but noob with WDK)