Playback apparatus, program, and playback method

Abstract

An Interactive Graphics Decoder 13 decodes a graphics stream, and overlays a Page including a plurality of Buttons on a moving picture. The Interactive Graphics Decoder 13 then executes a command corresponding to one of the plurality of Buttons on the Page, to thereby perform (1) a control of switching the Page to another Page and (2) a control of specifying a Button to be set in a selected state on the other Page. A judgment is made as to whether a button number of the specified Button is invalid. If the button number is invalid, an alternative value is written in a status register.

1 . A playback apparatus for playing back a graphics stream and a video stream, wherein
 the graphics stream includes one or more interactive control segments and one or more graphics data pieces,   each interactive control segment includes page information, which defines a screen structure of a multi-page menu, and time-out information,   each page information includes one or more button information pieces,   each button information piece is information for interactively displaying each graphics data piece as a state of a corresponding graphics button material on each of a plurality of pages constituting the multi-page menu,   the time-out information indicates a time on a playback time axis of the video stream at which the interactive screen structure is ended,   the playback apparatus comprises:   a plane memory storing therein graphics to be played back;   a decoding unit (i) obtaining a page including a plurality of graphics button materials by decoding the graphics stream, and (ii) writing the obtained page to the plane memory; and   a page number register storing therein a page number of a current page,   when a selection of one of the button materials on the current page is confirmed, the decoding unit executes a set command that sets a new page number in the page number register, and   when a current playback time has reached the time indicated by the time-out information, the decoding unit deletes, from the plane memory, the page that has been written thereto.   
     
     
         2 . A program for causing a computer to perform processing of playing back a graphics stream and a video stream, wherein
 the graphics stream includes one or more interactive control segments and one or more graphics data pieces,   each interactive control segment includes page information, which defines a screen structure of a multi-page menu, and time-out information,   each page information includes one or more button information pieces,   each button information piece is information for interactively displaying each graphics data piece as a state of a corresponding graphics button material on each of a plurality of pages constituting the multi-page menu,   the time-out information indicates a time on a playback time axis of the video stream at which the interactive screen structure is ended,   the computer comprises:   a plane memory storing therein graphics to be played back; and   a page number register storing therein a page number of a current page,   the program causes the computer to execute a decoding step of (i) obtaining a page including a plurality of graphics button materials by decoding the graphics stream, and (ii) writing the obtained page to the plane memory,   when a selection of one of the button materials on the current page is confirmed, the program further causes the computer to execute a set command, which sets a new page number in the page number register, in the decoding step, and   when a current playback time has reached the time indicated by the time-out information, the decoding step deletes, from the plane memory, the page that has been written thereto.   
     
     
         3 . A method used on a computer for playing back a graphics stream and a video stream, wherein
 the graphics stream includes one or more interactive control segments and one or more graphics data pieces,   each interactive control segment includes page information, which defines a screen structure of a multi-page menu, and time-out information,   each page information includes one or more button information pieces,   each button information piece is information for interactively displaying each graphics data piece as a state of a corresponding graphics button material on each of a plurality of pages constituting the multi-page menu,   the time-out information indicates a time on a playback time axis of the video stream at which the interactive screen structure is ended,   the computer comprises:   a plane memory storing therein graphics to be played back; and   a page number register storing therein a page number of a current page,   the method comprises a decoding step of, on the computer, (i) obtaining a page including a plurality of graphics button materials by decoding the graphics stream, and (ii) writing the obtained page to the plane memory,   when a selection of one of the button materials on the current page is confirmed, a set command is further executed in the decoding step, the set command setting a new page number in the page number register, and   when a current playback time has reached the time indicated by the time-out information, the decoding step deletes, from the plane memory, the page that has been written thereto.