Motion picture coding and decoding apparatus

A motion picture decoding apparatus receiving as inputs, lower layer decoded data obtained by coding a motion picture sequence with a first frame rate, upper layer coded data obtained by coding a specific area of said motion picture sequence with a second frame rate higher than said first frame rate, and a flag indicative of a method of synthesizing a lower layer frame, decoding the lower layer with said first frame rate, or for decoding the lower layer with said first frame rate and the upper layer with said second frame rate and superposing the upper and lower layers, comprising:

• a flag decoding unit for decoding said flag;
• a decoding unit for decoding, in the absence of a lower layer frame corresponding to a frame position the same as the upper layer frame, a first area shape and a second area shape indicative of area shapes of first and second lower layer frames preceding and succeeding the frame position, from said upper layer coded data;
• and
• a synthesizing unit for determining whether synthesization of said absent lower layer frame is to be performed or not using said first area shape, said second area shape and said first and second lower layer frames, based on the flag decoded by said flag decoding unit, and for synthesizing the lower layer frame.

A motion picture decoding apparatus, receiving as inputs lower layer coded data obtained by coding a motion picture sequence with a first frame rate, upper layer coded data obtained by coding a specific area of said motion picture sequence with a second frame rate higher than said first frame rate, and, for each frame of the upper layer, first and second flags indicative of whether a first area shape which is an area shape of a first lower layer preceding said frame in time and a second area shape which is an area shape of a second lower layer succeeding said frame in time are to be decoded, respectively, for decoding the lower layer with said first frame rate, or for decoding the lower layer with said first frame rate and the upper layer with said second frame rate and superposing the upper and lower layers, comprising:

• a flag decoding unit for decoding said first and second flags;
• a decoding unit for decoding in the absence of a lower layer frame corresponding to a frame position the same as the upper frame, the first area shape and the second area shape indicative of area shapes of the first and second lower layer frames preceding and succeeding the frame position, from said upper layer coded data;
• and
• a synthesizing unit for determining whether the first area shape and the second area shape are to be decoded based on the first and second flags decoded by said flat decoding unit, and when neither the first nor the second area shape is to be decoded, determining the area shapes used for synthesization last time to be the area shapes to be used for synthesization this time, and when only the second area shapes is to be decoded, determining the second area shape used for synthesization last time to be the first area shape to be used for synthesization this time, and for synthesizing said absent lower layer frame, using said first area shape, said second area shape and said first and second lower layer frames.

A motion picture coding apparatus for prediction coding a motion picture, wherein said motion picture includes a plurality of component motion images constituting said motion picture, said coding apparatus comprising:

• a flag coding unit for coding a flag indicating whether a reference component image used for said prediction coding belongs to a component motion image which is being coded;
• reference image identification information coding unit for coding identification information for identifying a reference component image used for said prediction coding, only when said flag indicates the reference component images does not belong to the component motion image which is being coded;
• and
• a reference image selecting unit for selecting a reference image from said plurality of component motion images in accordance with said flag or said identification information, wherein prediction coding is performed in accordance with said selected reference image.

A motion picture coding apparatus, comprising:

• a memory storing a reference image identification number of a previous frame;
• a comparing unit for comparing a reference image identification number of a present frame with the reference image identification number of the previous frame read from said memory;
• a flag generating unit for generating an off flag when the reference image identification numbers of said previous frame and the present frame are the same and generating an on flag if the identification numbers are different;
• and
• a flag coding and reference image identification number coding unit for coding only the flag when said flag is off and coding said flag and the reference image identification number of the present frame when said flag is on.

A motion picture decoding apparatus for decoding motion image data including a plurality of component motion images and coded data including a flag and identification information for identifying a reference component image for prediction coding encoded therein, comprising:

• a flag decoding unit for decoding a flag indicating whether a reference component image used for prediction coding belongs to a component motion image which is being coded;
• a reference image identification information decoding unit for decoding identification information for identifying a reference component image used for said prediction coding, only when said flag indicates the reference component image does not belong to the component image which is being coded;
• and
• a reference image selecting unit for selecting a reference image from said plurality of component motion images, in accordance with said decoded flag or said decoded identification information, wherein prediction decoding is performed in accordance with said selected reference image.