How does a video scrambler work?


It seems they only scramble CCTV cameras and not “regular” video cameras. Are there different ways of storing the data recorded or something?

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In the old days of CRT televisions, video was scrambled simply by inverting the sync signal that occurs between the raster lines. An analog television signal (broadcast, recorded on tape, whatever) contains video information for each raster line plus a signal to designate the boundary between lines, so that the television can sync the next raster sweep so that the elements of the picture line up vertically. Invert the sync, and the television gets confused, resulting in scrambled (or at least very unstable) video.

Nowadays everything is digital. There are many easy ways to scramble digital data. One can swap bits around, perform logical operations on them, and so on, which would need to be reversed by the onboard processor before displaying the video.