Supplementary digital data is encoded together with a video signal by predicting the intensity values of a first set of video samples, compressing the range of the prediction errors and superimposing a value indicative of the supplementary data on the compressed value. The samples in the first set may...http://www.google.ca/patents/US4237484?utm_source=gb-gplus-sharePatent US4237484 - Technique for transmitting digital data together with a video signal
