Patent ID: 8139915

Claim:
A reproduction apparatus for reproducing a digital stream generated by multiplexing a video stream and a graphics stream, the reproduction apparatus comprising: a video decoder operable to decode the video stream to generate a moving picture; and a graphics decoder operable to decode the graphics stream to generate graphics object, wherein: the graphics decoder includes an object buffer for storing the graphics object generated by the decoding; the graphics stream includes a plurality of display sets each of which includes a presentation composition segment and an object definition segment for providing a new graphics object to the object buffer; if a display set belongs to a same memory management unit as an immediately preceding display set, and the graphics object referenced by the presentation composition segment in the display set has a same identifier as the graphics object in the immediately preceeding display set, the graphics object referenced by the presentation composition segment in the display set is made up of a same number of horizontal pixels and a same number of vertical pixels as the graphics object in the immediately preceeding display set, and the graphics decoder stores the graphics object referenced by the presentation composition segment in the display set into a same area of the object buffer as the graphics object in the immediately preceeding display set, so as to overwrite the graphics object in the immediately preceeding display set.