A playback time axis of a video stream is composed of a plurality of frame periods. To overlay a rendered image with a stereoscopic video image to be displayed in the i-th frame period, a process of writing to a left-view plan memory and a process of writing to a right-view plane memory both need to be completed before the start of the i-th frame period. To simultaneously request the two rendering processes, the argument of an application interface includes a pair of specifications, one specifying writing to the left-view plane memory and the other specifying writing to the right-view plane memory.