Motion vector composition in low-delay hierarchical P-frame coding

Recent video coding standards such as high efficiency video coding (HEVC) and multi-view video coding (MVC) can obtain significant gain from hierarchical prediction structures. Hierarchical B structure utilizes future reference frames, which induces high encoding delay. Comparatively, hierarchical P structure brings low-delay coding in which no future references are involved. The only hurdle of the low-delay hierarchical P structure is the need of motion estimation in distant reference frames. To maintain a high coding efficiency, large search range for motion estimation was commonly adopted in distant reference pictures. Therefore, computational complexity will be increased dramatically. In this paper, motion vector composition is proposed in hierarchical P structure to shorten coding process. Simulation results reveal that the proposed scheme can achieve significant complexity savings.