To provide an adaptive selection method by which priority control of a memory access in a motion picture experts group(MPEG) processing unit is conducted to attain a balanced use of a band width of a memory bus.

An MPEG processor 100 is provided with a plurality of function modules, that is an input interface 110, a CPU 120, a voice decoder 130, a video decoder 140, a voice processor 132, a video processor 142 and a memory controller 150. Each of a plurality of the modules receives memory access control to a data bus MEM-BUS by the arbitration of the memory controller 150. The access priority of the CPU 120 over the data bus MEM-BUS is maintained lower relatively except that the CPU requires execution of analysis of MPEG compression data and initial decoding of voice compression data is executed. Thus, the use of band width of a data bus is balanced between system resources 400 and then the performance of the entire system is improved.