Method and apparatus for standardizing nonstandard video signals

A method and apparatus are disclosed for converting nonstandard video signals, such as generated by popular micro computers to N.T.S.C. video standard signals. The nonstandard video is digitized and temporarily stored in one or more line memories. The data is then removed from the line memories by a clock signal related to a N.T.S.C. source. A luminance and chrominance converter circuit converts the horizontal scan frequency from an even harmonic to an odd harmonic of the color subcarrier so that the luminance information is properly related to the horizontal timing and chrominance is properly related to the color subcarrier. The corrected signal can be gen-locked to an external video signal and superimposed on such external signal.