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

Abstract

Apparatuses encode or decode a picture sequence, some having different resolutions, and store a bitstream of encoded video data. The apparatus has a processor, which decodes a first syntax element for specifying a reference size of pictures referring to the high-level syntax structure and 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 processor derives 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 processor generates 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. The processor reconstructs a residual block from the bitstream and reconstructs the current block based on adding the prediction block and the residual block.