Patent Document ID: 9693074
Application ID: 15338754
Patent Status: 1

Claim One:
1. A picture decoding method for decoding a current block included in a current picture in direct mode, the picture decoding method comprising: specifying, when a co-located block has two motion vectors, only one motion vector out of the two motion vectors, the co-located block being located in a second picture at the same position that the current block is located in the current picture, the second picture being a B-picture following the current picture in display order; determining a first motion vector and a second motion vector of the current block, using the specified one motion vector; generating a first predictive image of the current block using the first motion vector of the current block and a second predictive image of the current block using the second motion vector of the current block; generating a predictive image of the current block based on the first predictive image and the second predictive image; decoding a coded difference image of the current block to obtain a decoded difference image of the current block; and reconstructing the current block by adding the decoded difference image of the current block and the predictive image of the current block, wherein, in the case where the co-located block is motion compensated using two motion vectors which refer to a same one reference picture preceding the second picture in display order, one motion vector among the two motion vectors of the co-located block which appears earlier in a bit stream is specified as the only one motion vector of the co-located block in said specifying.