US Patent 7209520 Moving picture encoding method and moving picture decoding method

A moving picture coding apparatus 1 includes a counter unit 102 which counts the number of pictures following an intra coded picture; and a motion estimation unit 101 which compares respectively only reference pictures which are the intra coded picture or the following pictures, selected from among a reference picture Ref1, a reference picture Ref2 and a reference picture Ref3 stored in memories 408˜410, with a picture signal Vin, and determines the reference picture whose inter picture differential value is smallest.