Hierarchical global motion estimation/compensation in low bitrate video coding

In this paper, we develop a hierarchical global motion estimation/compensation system which is used to improve the block-based motion compensation in the current low bitrate video coding standard H.263. The system first detects the background motion by examining the local motion information using hierarchical block matching and global motion estimation algorithm. If the background motion exists, the global motion compensation (GMC) is applied to the image before the H.263 block-based coding. Experiments are done under the typical low bitrate video conditions: low resolution and low frame rate. The results show that prediction errors on both motion vectors and texture are reduced. For sequences containing lots of background motion, the proposed system shows savings of up to 30% in total bitrate.