Block Merging for Quadtree-Based Partitioning in HEVC

The joint development of the upcoming High Efficiency Video Coding (HEVC) standard by ITU-T Video Coding Experts Group and ISO/IEC Moving Picture Experts Group marks a new step in video compression capability. In technical terms, HEVC is a hybrid video-coding approach using quadtree-based block partitioning together with motion-compensated prediction. Even though a high degree of adaptability is achieved by quadtree-based block partitioning, this approach has certain intrinsic drawbacks, which may result in redundant sets of motion parameters being transmitted. Previous work has shown that those redundancies can effectively be removed by merging the leafs of a particular quadtree structure. Following this concept, a block merging algorithm for HEVC is now proposed. This algorithm generates a single motion parameter set for a whole region of contiguous motion-compensated blocks. In this paper, we describe the various components of the proposed block merging algorithm and, using experimental evidence, demonstrate their benefits in terms of coding efficiency.