Patent ID: 7295249

Claim:
Apparatus for controlling a digital television display, the apparatus comprising: a main processor; a main memory coupled to said main processor via address and data busses, the main memory being arranged to store at least temporarily video data for display, and on-screen display graphics for overlaying on video data; mixing means for mixing video data read from the main memory under the control of the main processor, with on-screen display graphic data; at least one line buffer for storing a line of on-screen display graphic data; hardware processing means for composing a line of on-screen display graphic data in the line buffer by reading appropriate on-screen display graphic data from said main memory and writing it to the line buffer, and for providing the composed line of data to said mixing means; a first memory for storing a list of on-screen display objects; and a second memory for storing object descriptors, each entry in said list pointing to an object descriptor, and each descriptor specifying a bitmap stored in said main memory.