Mapping motion vectors from a plurality of reference frames to a single reference frame

摘要

Motion vectors of a first reference frame RefC are initially permitted to point to a plurality of further reference frames RefO-Ref3. A method of storing the motion vectors, which can reduce the memory required, comprises selecting one of the further reference frames such as RefO. Then, each motion vector of the first reference frame RefC that points to one of the further reference frames Ref1- Ref3 other than the selected further reference frame is mapped to the selected reference frame so that after the mapping all the motion vectors of the first reference frame RefC point to the selected reference frame RefO. The motion vectors subjected to this mapping, which may involve scaling, are then stored. Consequently, as all available motion vectors will now end in the same reference frame RefO, there is thus no need to store or transmit the index of the reference frame since the reference index is unique. The further reference frame may be selected on the basis of: which further reference frame is temporally closest to the first reference frame, or which further reference frame has the minimum Picture Order Count (POC) difference from the first reference frame.