Patent ID: 7733960

Claim:
A motion vector determining method for determining a motion vector of a current block included in a current picture, said motion vector determining method comprising: specifying a co-located block which is a block included in a second picture that is different from the current picture, the co-located block being located in the second picture at the same position that the current block is located in the current picture; and determining first and second motion vectors for performing motion compensation on the current block, using a third motion vector which is a motion vector of the co-located block, wherein, in the case where a reference picture referred to by the third motion vector is stored in a long term picture buffer, (i) the first motion vector, which refers to the reference picture stored in the long term picture buffer, is determined to be equal to the third motion vector, and (ii) the second motion vector, which refers to the second picture that is different from the current picture, is determined to be equal to a value of 0.