Video decoder for determining a motion vector from a scaled vector and a difference vector

摘要

A video decoding apparatus including a memory for storing at least first and second reference pictures, a prediction signal forming circuit for forming a prediction signal to produce an output signal, using a first reference signal designated by a first motion vector for the first reference picture and a second reference signal designated by a second motion vector for the second reference picture read out of the memory. Also included is a decoding circuit for decoding the transmitted first motion vector and a transmitted motion vector difference, and for further decoding the second motion vector by adding a scaled motion vector and the motion vector difference. The scaled motion vector is derived by scaling the first motion vector to a motion vector for the second reference picture. Further included is a decoding circuit for decoding a transmitted difference signal and for obtaining the output signal by adding the difference signal and the prediction signal.