A television display device for use with a television display for displaying television services, an input for providing at least one command to the television display device and a broadcast stream containing a stream of key files including data representing respective key images, the television display...http://www.google.fr/patents/US7886320?utm_source=gb-gplus-shareBrevet US7886320 - Television display device and method of operating a television system
Television display device and method of operating a television system
