Genlocked digital overlay on a video signal

The synchronization problems involved in mixing computer graphics with a video signal are outlined, and it is shown how two components solve them. The components, a video encoder and a genlocking digitizer facilitate overlays of digital computer graphics and/or text data onto a standard analog NTSC (National Television System Committee) or PAL baseband television signal. The mapping of the clock and subcarrier recovery algorithm and the video encoding procedure into the architectures of the two chips is discussed