Recording medium, recording method, reproduction apparatus and method, and computer-readable program

A reproduction apparatus for reproducing a digital stream generated by multiplexing a video stream and a graphics stream, 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, and overlay the graphics and the moving picture, wherein:
• the graphics decoder includes an object buffer for storing the graphics generated by the decoding;
• the graphics stream includes a plurality of display sets each of which includes a control segment and graphics data;
• and
• when processing the display set and an immediately preceding display set in a pipeline, the graphics decoder stores graphics generated by decoding the graphics data in the display set into a different area of the object buffer from graphics generated by decoding graphics data which is referenced by a control segment in the immediately preceding display set.

A method of recording onto a recording medium, comprising the steps of:

• generating application data;
• and
• recording the application data to the recording medium, wherein:
• the application data includes a digital stream generated by multiplexing a video stream and a graphics stream;
• the graphics stream includes a plurality of display sets each of which is used for a graphics display;
• the display set includes a control segment and graphics data that is assigned an identifier;
• and
• if an active period of the control segment in the display set overlaps with an active period of a control segment in an immediately preceding display set on a reproduction time axis of the video stream, the identifier assigned to the graphics data in the display set differs from an identifier assigned to graphics data which is referenced by the control segment in the immediately preceding display set.

A computer-readable program used for enabling a computer to reproduce a digital stream generated by multiplexing a video stream and a graphics stream, the program enabling the computer to perform the steps of:

• decoding the video stream to generate a moving picture;
• and
• decoding the graphics stream to generate graphics, and overlaying the graphics and the moving picture, wherein:
• the graphics stream includes a plurality of display sets each of which includes a control segment and graphics data;
• and
• when processing the display set and an immediately preceding display set in a pipeline, the step of decoding the graphics stream stores graphics generated by decoding the graphics data in the display set into a different area of an object buffer from graphics generated by decoding graphics data which is referenced by a control segment in the immediately preceding display set.

A method of reproducing a digital stream generated by multiplexing a video stream and a graphics stream, comprising the steps of:

• decoding the video stream to generate a moving picture;
• and
• decoding the graphics stream to generate graphics, and overlaying the graphics and the moving picture, wherein:
• the graphics stream includes a plurality of display sets each of which includes a control segment and graphics data;
• and
• when processing the display set and an immediately preceding display set in a pipeline, the step of decoding the graphics stream stores graphics generated by decoding the graphics data in the display set into a different area of an object buffer from graphics generated by decoding graphics data which is referenced by a control segment in the immediately preceding display set.