Circuitry that synchronizes one video signal to another video signal. There are three types of genlock: V-lock, HV-lock and full color. • V-lock is useful when simply switching from one B/W color source to another • HV-lock is used for full synchronization of B/W cameras, and requires a HD + VD input, composite sync input or composite VS video signal input. In the case of color cameras, this type of synchronization can be used when cutting between pictures, but not for mixing between them. • Full color genlock is used when pictures have to be mixed without color degradation. It needs VBS composite video input.