Quad processors can be used to connect four analogue cameras to a single video input. They work by combining the video from four cameras into one analogue output, which is split into quarters. SecuritySpy can be set to treat this as four independent cameras.

Using a quad processor and one video input is in many cases cheaper and more practical than installing four separate video inputs.

However, because the video input resolution is shared between four cameras, the maximum resolution of each camera is only half of the video input's resolution. This is the biggest drawback of using quad processors, despite the fact that it results in lower system demands.

Quad processors cannot be used in conjunction with network video servers.