A controller issues a command to an HDD interface to transfer AV data stored in HDDs to a memory. The HDD interface, in compliance with the command, transfers the AV data stored in the HDDs to a memory mapped on a bus. A memory controller reads the AV data out of the bus, and writes the AV data into the memory. The controller outputs the address of the AV data to be outputted to the memory controller. The memory controller reads out the AV data of the designated address, and outputs them to an AV data output interface. And the AV data output interface outputs the AV data. The controller issues a command to the HDD interface memory to record the AV data stored in the memory into the HDDs. The HDD interface, in compliance with the command, reads the data out of a memory mapped on the bus, and stores them in the HDDs. The memory controller reads the AV data out of the memory, and outputs them to the bus. At the same time, the controller designates to the memory controller the address in the memory into which the AV data inputted from the AV data input interface are to be written. The memory controller reads the AV data out of the AV data input interface, and writes them into the designated memory. By accomplishing this series of actions in synchronism with the frame period, AV data are stored in the HDDs, and also AV data stored in the HDDs are outputted.