To reduce scale of an audio/video synchronous control circuit by using a small-sized buffer for decoding without depending on size of an access unit of an input file in an audio/video synchronous control system.

Data quantity at a fixed time interval is calculated based on size information and time stamp information about each access units to be obtained from an input file including compressed and coded audio/video data. Audio data and video data having the data quantity are stored in an audio buffer and a video buffer, respectively according to the calculated time interval. Data transfer frequencies are calculated based on the time stamp information. The audio data and the video data are transferred to an audio decoder and a video decoder according to the calculated data transfer frequencies.