The GS4901B is a highly flexible, digitally controlled clock synthesis circuit and timing generator with genlock capability. It can be used to generate video and audio clocks and timing signals, and allows multiple devices to be genlocked to an input reference. The GS4900B includes all the features of the GS4901B, but does not offer audio clocks or AFS pulse generation. The GS4901B/GS4900B will recognize input reference signals conforming to 36 different video standards, and will genlock the output timing information to the incoming reference. The GS4901B/GS4900B supports cross-locking, allowing the output to be genlocked to an incoming reference that is different from the output video standard selected.