Patent ID: 8655089

Claim:
A method for a moving picture decoding device to calculate a prediction motion vector of a block to be decoded in a B picture when decoding a moving picture, the method comprising: obtaining, by the moving picture decoding device, at least one motion vector of a block other than the block to be decoded in the B picture, wherein the other block refers to at least one reference picture pointed to by a reference picture index for a plurality of reference pictures; obtaining, by the moving picture decoding device, a first picture order count value of the B picture, wherein the first picture order count value represents a display order of the B picture; obtaining, by the moving picture decoding device, a second picture order count value of the at least one reference picture, wherein the second picture order count value represents a display order of the at least one reference picture; comparing, by the moving picture decoding device, the first picture order count value for the B picture with the second picture order count value for the at least one reference picture; and deriving, by the moving picture decoding device, the prediction motion vector of the block to be decoded in the B picture from the motion vector of the block other than the block to be decoded, based on the comparison step.