Image decoding apparatus, integrated circuit, image decoding method, and image decoding system

An integrated circuit that sequentially decodes, in a predetermined order, a plurality of macroblocks included in a coded picture, the integrated circuit comprising:

• a non-transitory memory storing a program;
• and
• a hardware processor configured to execute the program and cause the integrated circuit to operate as:
• a transfer unit configured to perform data communication with an external memory that stores a motion vector of a co-located macroblock corresponding to each of the macroblocks;
• a buffer;
• a first decoding unit configured to sequentially decode the macroblocks;
• a second decoding unit configured to decode, before the first decoding unit completes decoding a v-th macroblock, at least determination information corresponding to a w-th macroblock, the determination information being for determining whether or not a motion vector of a co-located macroblock corresponding to the w-th macroblock is to be transferred to the buffer for calculating a motion vector for the w-th macroblock, v being an integer equal to or larger than 1, w satisfying w≧v+1, and the v-th macroblock and the w-th macroblock being included in the macroblocks;
• and
• a determining unit configured to determine, from the determination information decoded by the second decoding unit, whether or not the motion vector of the co-located macroblock corresponding to the w-th macroblock is necessary for calculating the motion vector for the w-th macroblock,
• wherein:
• the transfer unit is configured
• to transfer the motion vector of the co-located macroblock corresponding to the w-th macroblock from the external memory to the buffer when the determining unit determines that the motion vector of the co-located macroblock corresponding to the w-th macroblock is necessary for calculating the motion vector for the w-th macroblock, and to not transfer the motion vector of the co-located macroblock corresponding to the w-th macroblock from the external memory to the buffer when the determining unit determines that the motion vector of the co-located macroblock corresponding to the w-th macroblock is not necessary for calculating the motion vector for the w-th macroblock, and
• the second decoding unit is configured to transmit the decoded determination information to the first decoding unit.

An image decoding method performed by an image decoding apparatus that sequentially decodes a plurality of macroblocks in a predetermined order, the macroblocks being included in a coded picture, the image decoding apparatus including:

• a transfer unit configured to perform data communication with an external memory that stores a motion vector of a co-located macroblock corresponding to each of the macroblocks;
• a buffer;
• a first decoding unit configured to sequentially decode the macroblocks;
• and
• a second decoding unit configured to decode, before the first decoding unit completes decoding a v-th macroblock, at least determination information corresponding to a w-th macroblock, the determination information being for determining whether or not a motion vector of a co-located macroblock corresponding to the w-th macroblock is to be transferred to the buffer for calculating a motion vector for the w-th macroblock, v being an integer equal to or larger than 1, w satisfying w≧v+1, and the v-th macroblock and the w-th macroblock being included in the macroblocks, and
• the image decoding method comprising:
• determining, from the determination information decoded by the second decoding unit, whether or not the motion vector of the co-located macroblock corresponding to the w-th macroblock is necessary for calculating the motion vector for the w-th macroblock;
• and
• transferring the motion vector of the co-located macroblock corresponding to the w-th macroblock from the external memory to the buffer by the transfer unit, when it is determined in the determining step that the motion vector of the co-located macroblock corresponding to the w-th macroblock is necessary for calculating the motion vector for the w-th macroblock, and not transferring the motion vector of the co-located macroblock corresponding to the w-th macroblock from the external memory to the buffer when it is determined that the motion vector of the co-located macroblock corresponding to the w-th macroblock is not necessary for calculating the motion vector for the w-th macroblock,
• wherein the second decoding unit is configured to transmit the decoded determination information to the first decoding unit.

An image decoding system, comprising:

• an image decoding apparatus that sequentially decodes, in a predetermined order, a plurality of macroblocks included in a coded picture;
• and
• an external memory that stores a motion vector of a co-located macroblock corresponding to each of the macroblocks,
• the image decoding apparatus including:
• a non-transitory memory storing a program;
• and
• a hardware processor configured to execute the program and cause the image decoding apparatus to operate as:
• a transfer unit configured to perform data communication with the external memory;
• a buffer;
• a first decoding unit configured to sequentially decode the macroblocks;
• a second decoding unit configured to decode, before the first decoding unit completes decoding a v-th macroblock, at least determination information corresponding to a w-th macroblock, the determination information being for determining whether or not a motion vector of a co-located macroblock corresponding to the w-th macroblock is to be transferred to the buffer for calculating a motion vector for the w-th macroblock, v being an integer equal to or larger than 1, w satisfying w≧v+1, and the v-th macroblock and the w-th macroblock being included in the macroblocks;
• and
• a determining unit configured to determine, from the determination information decoded by the second decoding unit, whether or not the motion vector of the co-located macroblock corresponding to the w-th macroblock is necessary for calculating the motion vector for the w-th macroblock,
• wherein:
• the transfer unit is configured
• to transfer the motion vector of the co-located macroblock corresponding to the w-th macroblock from the external memory to the buffer when the determining unit determines that the motion vector of the co-located macroblock corresponding to the w-th macroblock is necessary for calculating the motion vector for the w-th macroblock, and to not transfer the motion vector of the co-located macroblock corresponding to the w-th macroblock from the external memory to the buffer when the determining unit determines that the motion vector of the co-located macroblock corresponding to the w-th macroblock is not necessary for calculating the motion vector for the w-th macroblock, and
• the second decoding unit is configured to transmit the decoded determination information to the first decoding unit.