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

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

• generating application data by using an authoring device;
• 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 is a sequence of packets, the packets constituting the graphics stream include two types, one of which is packets containing graphics data and the other is packets containing control data, the sequence of packets includes a pair of a packet containing graphics data and a packet containing control data, the pair is followed by a packet containing control data that performs a forward reference,
• the control data that performs the forward reference indicates that graphics, which corresponds to the graphics data contained in the pair of packets which precedes the control data that performs the forward reference, is to be displayed,
• the digital stream is supplied to a reproduction apparatus that includes:
• a video decoder configured to decode the video stream to generate a moving picture;
• a graphics decoder configured to decode the graphics stream to generate graphics;
• and a plane memory,
• the graphics decoder includes:
• an object buffer;
• a processor configured to generate graphics on the object buffer by decoding the graphics data contained in the pair of packets;
• and
• a controller configured to execute a graphics display by writing the graphics generated on the object buffer into a partial area in the plane memory, based on the control data contained in the pair of packets, wherein
• the plane memory is a memory for overlay with moving pictures and is provided in the reproduction apparatus, and
• a packet storing the control data that performs the forward reference includes a time stamp, and
• a time indicated by the time stamp in the packet storing the control data that performs the forward reference is a timing at which the graphics decoder is controlled to update the graphics display by writing the graphics generated on the object buffer into the partial area based on the control data that performs the forward reference.

A non-transitory computer-readable recording medium storing a program for causing a computer to reproduce a digital stream generated by multiplexing a video stream and a graphics stream comprising the steps of:

• program code configured to cause the computer to decode the video stream to generate a moving picture;
• and program code configured to cause the computer to decode the graphics stream to generate graphics, and display the graphics;
• wherein the graphics stream is a sequence of packets, the packets constituting the graphics stream include two types, one of which is packets containing graphics data and the other is packets containing control data, the sequence of packets includes a pair of a packet containing graphics data and a packet containing control data, the pair is followed by a packet containing control data that performs a forward reference, the control data that performs the forward reference indicates that graphics, which corresponds to the graphics data contained in the pair of packets which precedes the control data that performs the forward reference, is to be displayed, the graphics generating program code includes:
• a sub-program code configured to generate graphics on an object buffer provided in the computer by decoding the graphics data contained in the pair of packets:
• and a sub-program code configured to execute a graphics display by writing the graphics generated on the object buffer into a partial area in a plane memory provided in the computer, based on the control data contained in the pair of packets, wherein the plane memory is a memory for overlay with moving pictures, and when control data that performs a forward reference has been read into the graphics decoder from a recording medium, the graphics display executing sub-program code updates the graphics display by writing, at a time indicated by the time stamp in a packet storing the control data that performs the forward reference, the graphics generated on the object buffer into the partial area again based on the read control data that performs the forward reference.

A method of causing a computer to reproduce a digital stream generated by multiplexing a video stream and a graphics, comprising the steps of:

• decoding the video stream to generate a moving picture;
• and
• decoding the graphics stream to generate graphics, and display the graphics, wherein
• the graphics stream is a sequence of packets, the packets constituting the graphics stream include two types, one of which is packets containing graphics data and the other is packets containing control data, the sequence of packets includes a pair of a packet containing graphics data and a packet containing control data, the pair is followed by a packet containing control data that performs a forward reference,
• the control data that performs the forward reference indicates that graphics, which corresponds to the graphics data contained in the pair of packets which precedes the control data that performs the forward reference, is to be displayed,
• the graphics decoding step includes the sub-steps of:
• generating graphics on an object buffer provided in the computer by decoding the graphics data contained in the pair of packets;
• and
• executing a graphics display by writing the graphics generated on the object buffer into a partial area in the plane memory provided in the computer, based on the control data contained in the pair of packets, wherein
• the plane memory is a memory for overlay with moving pictures, and
• when control data that performs the forward reference has been read into the graphics decoder from a recording medium, the graphics display executing sub-step updates the graphics display by writing, at a time indicated by a time stamp in the packet storing the control data that performs the forward reference, the graphics generated on the object buffer into the partial area based on the read control data that performs the forward reference.

A reproduction apparatus for reproducing a digital stream generated by multiplexing a video stream and a graphics stream, comprising:

• a video plane;
• a graphics plane;
• a video decoder configured to decode the video stream to generate a moving picture, and store a picture constituting the moving picture into the video plane;
• a graphics decoder configured to decode the graphics stream to generate graphics, and store the generated graphics into the graphics plane;
• and
• an adder configured to overlay the graphics and the moving picture by performing addition for corresponding pixels in the picture stored in the video plane and the graphics stored in the graphics plane, wherein
• the graphics stream is a sequence of packets, the packets constituting the graphics stream include two types, one of which is packets containing graphics data and the other is packets containing control data, the sequence of packets includes a pair of a packet containing graphics data and a packet containing control data, the pair is followed by a packet containing control data that performs a forward reference,
• the control data that performs the forward reference indicates that graphics, which corresponds to the graphics data contained in the pair of packets which precedes the control data that performs the forward reference, is to be displayed,
• the graphics decoder includes:
• an object buffer;
• a processor configured to generate graphics on the object buffer by decoding the graphics data contained in the pair of packets;
• and
• a controller configured to execute a graphics display by writing the graphics generated on the object buffer into a partial area in the plane memory, based on the control data contained in the pair of packets, wherein
• when control data that performs the forward reference has been read into the graphics decoder from a recording medium, the graphics display executing sub-step updates the graphics display by writing, at a time indicated by a time stamp in the packet storing the control data that performs the forward reference, the graphics generated on the object buffer into the partial area based on the read control data that performs the forward reference.

A method of recording onto a recording medium, comprising the steps, which are referred to by an authoring device, of:

• generating a graphics stream;
• multiplexing a video stream and the graphics stream;
• and
• recording a digital stream, which is obtained by the multiplexing, on the recording medium, wherein
• the graphics stream generating step includes the sub-steps of:
• storing the graphics data and the control data into different packets, respectively;
• arranging, serially, packets storing the graphics data and packets storing the control data to obtain a graphics stream, wherein
• in the storing sub-step, when the control data is stored into a packet, a time stamp is included into the packet that stores the control data,
• the digital stream is supplied to a reproduction apparatus that includes:
• a video decoder configured to decode the video stream to generate a moving picture;
• a graphics decoder configured to decode the graphics stream to generate graphics;
• and a plane memory,
• the graphics stream is a sequence of packets, the packets constituting the graphics stream include two types, one of which is packets containing graphics data and the other is packets containing control data, the sequence of packets includes a pair of a packet containing graphics data and a packet containing control data, the pair is followed by a packet containing control data that performs a forward reference,
• the control data that performs the forward reference indicates that graphics, which corresponds to the graphics data contained in the pair of packets which precedes the control data that performs the forward reference, is to be displayed,
• the graphics decoder includes:
• an object buffer;
• a processor configured to generate graphics on the object buffer by decoding the graphics data contained in the pair of packets;
• and
• a controller configured to execute a graphics display by writing the graphics generated on the object buffer into a partial area in the plane memory, based on the control data contained in the pair of packets, wherein
• the plane memory is a memory for overlay with moving pictures, and
• a time indicated by the time stamp in the packet storing the control data that performs the forward reference is a timing at which the graphics decoder is controlled to update the graphics display by writing the graphics generated on the object buffer into the partial area based on the control data that performs the forward reference.