Patent ID: 9485516
Filing Date: 2016-11-01
CPC Classification: H04N

Claim Text:
1. A picture decoding method for decoding a current block of a current macroblock included in a current B picture in direct mode, with reference to a motion vector of an adjacent macroblock that is located adjacent to the current macroblock, the picture decoding method comprising: obtaining a reference motion vector from a block for which motion compensation has been performed, the block being included in a co-located block, the co-located block being included in a co-located macroblock, the co-located macroblock being included in a picture subsequent in display order to the current B picture, wherein the size of the block is smaller than the size of the current block and the size of the co-located block is the same as the current block and wherein the block is located in a corner of the co-located macroblock; specifying plural adjacent macroblocks which are located adjacent to the current macroblock; determining a motion vector of the current block to be decoded for performing motion compensation on the current block using the obtained reference motion vector; generating a predictive image of the current block by using the determined motion vector of the current block; decoding a coded difference image between the current block and the generated predictive image of the current block to obtain a decoded difference image of the current block; and recovering a reconstructed image of the current block by adding the generated predictive image of the current block and the decoded difference image of the current block, wherein, in the case where a size of the obtained reference motion vector is a predetermined value or less, the motion vector of the current block is determined to be “0”, and in the case where the size of the obtained reference motion vector exceeds the predetermined value, the motion vector of the current block is determined to be a median of plural motion vectors of the plural adjacent macroblocks, wherein, the motion vector of the adjacent macroblock is determined to be a motion vector of a motion compensated block included in the adjacent macroblock in the case where a size of the motion compensated block is the same as a size of the adjacent macroblock, and the motion vector of the adjacent macroblock is determined to be a motion vector of a 4×4 block included in the adjacent macroblock in the case where a size of the motion compensated block is smaller than a size of the adjacent macroblock, wherein (1) the 4×4 block is a block located on the upper-right corner of the adjacent macroblock in the case that the adjacent macroblock is located to the left of the current macroblock, and (2) the 4×4 block is a block located on the lower-left corner of the adjacent macroblock in the case that the adjacent macroblock is located above the current macroblock, and (3) the 4×4 block is a block located on the lower-left corner of the adjacent macroblock in the case that the adjacent macroblock is located above-right of the current macroblock.