This invention describes a method and apparatus for vertically locking input and output video frame rates. The output vertical sync pulse is locked in phase with the input vertical sync pulse, regardless of the input format and frequency. The output resolution, horizontal refresh rate, and delay are...http://www.google.co.uk/patents/US6441658?utm_source=gb-gplus-sharePatent US6441658 - Method and apparatus for vertically locking input and output signals
