Switching Video Cameras through Motion Detection

The device is using the intelligent method of motion detection to allow the video switcher to monitor up to 4 security cameras.

Storing a complete video frame and then looking for changes on successive frames is the usual way to detect motion. Several problems can be saved by only sampling 64 locations on the screen at a low resolution. There is still a lot of data to be stored in the PIC since this device is designed for up to 4 cameras. To greatly reduce the memory requirements, another method was introduced whereby the PIC grabs 8×8 low resolution video frames and then calculates numeric sums of screen regions to detect motion by detecting image changes.

The video switcher will read one sample per video line while line skewing has no practical difference because it may seem that OIC microcontrollers are too slow for taking frame or even single video line at once. Each of 4 video inputs goes to both U1 and U2 where U1 controls which input is routed out to monitor and U2 controls which input goes to detection circuit. Any detected IR signal switches to the next camera.

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