Video switcher allows monitoring up to 4 security video cameras. Interesting thing is that device uses intelligent method of motion detection. PIC grabs low resolution (8×8) video frames and then calculates numeric sums of screen regions to detect motion by detecting image changes.
Of course it may seem that PIC microcontrollers are too slow for taking frame or even single video line at once. So it reads one sample per video line while line skewing has no practical difference. This way it collects all 64 data points. The Source File only implements the 4 cameras. You can connect any number from 1 to 4 and the software will sort out the detection and switching. Motion on any video input switches the output immediately to that source.