Patent ID: 7675974

Claim:
A video encoder for encoding a motion picture signal, comprising: means for sequentially selecting one reference picture signal from a plurality of reference picture signals; means for setting a center of search on a reference picture indicated by each of the reference picture signals sequentially selected; means for setting, on the reference picture, a search range including the center of search; means for performing block matching in the search range to search for a motion vector; means for repeatedly performing, for a target block in the motion picture signal, selection of each of the reference picture signals, setting of the center of search, setting of the search range, and the search for the motion vector, thereby acquiring an optimal motion vector, and for then performing motion compensation on each of the reference picture signals sequentially selected, using the optimal motion vector, to generate a predicted picture signal; and means for encoding a signal indicating a difference between the target block in the motion picture signal and the predicted picture signal, and side information, wherein the means for setting the search range on the reference picture indicated by a last one of the reference picture signals sequentially selected, sets the search range based on information related to the motion vector detected in the search range set on the reference picture indicated by a second last one of the reference picture signals, and wherein the means for setting the search range sets the search range to enable the means for searching for the motion vector to select the motion vector from all vector candidates m that satisfy the following algebraic expression: R 2( m )< R 0−( SAD 1 −ΔESAD−SAD 0)/λ M SAD 2 =SAD 1 −ΔESAD where R 0 and SAD 0 represent a number of coded bits of side information and SAD, respectively, and correspond to a currently searched motion vector MV 0 , R(m) represents the number of coded bits of the side information, SAD 1 represents SAD at the center of search, SAD 2 represents SAD corresponding to a motion vector MV 2 to be now searched for, ΔESAD represents a predicted reduction value of SAD 2 with respect to SAD 1 , and λ M represents a Lagrangian multiplier, SAD representing a sum of absolute differences between the motion picture signal and each of the reference picture signals sequentially selected.