I made a patch for school last year that involved motion detection through a webcam. My problem is that I seem to have deleted it inadvertently and though I can remember how I did it, I can’t remember the details.

Specifically there was one stage where identical frames would be subtracted from the output so that whenever no one was moving it wouldn’t send any information.

I can’t for the life of me remember how I did this. Does anyone have any ideas?