Method and apparatus for inter-prediction of pictures with different resolutions

Abstract

Methods encode or decode a picture sequence, some having different resolutions, and store a bitstream of encoded video data. A decoding method includes decoding a first syntax for specifying a reference size of pictures referring to a high-level syntax structure and decoding a second syntax element for specifying a picture size scaled from the reference size of the pictures referring to the high-level syntax structure. The method includes deriving at least one offset factor and at least one scale factor representing a scale difference between a current picture including a current block to be decoded and a reference picture referred to by the current block. The method includes generating a prediction block of the current block from the reference picture by using the motion vector of the current block, the at least one scale factor, and the at least one offset factor, reconstructing a residual block from the bitstream, and reconstructing the current block based on adding the prediction block and the residual block.