DIGITAL SIGNAL PROCESSING CIRCUIT

PURPOSE: To perform the signal processing after sampling by the use of one kind of clock in the case where performing digital processing of plural video signals sampled by the number of samples different from each other. CONSTITUTION: The video signal from an input terminal 1 is digitally converted in an A/D conversion part 2 with the clock from a write clock generating part 7 to be written in a memory part 6 by the amount equivalent to 1H under the write control of a memory controller 6 and then this data are read out by the readout control from the memory controller 6 based on the clock generated in a read clock generating part 8 to be inputted to a picture processing part 4 and are subjected to a picture processing to be transmitted to a display part 5 to be displayed on a screen. Moreover, the on-screen signal synchronized with the read clock is generated in an on-screen signal generating part 9 to be inputted to the picture processing part 4 and then this signal is synthesized with the signal from the memory part 3. Further, the write clock generating part 7 generates clocks having frequencies corresponding to video signal sources and the read clock generating part 8 always generates one king of the clock.