Block merging for quadtree-based video coding

Quadtree-based block partitioning together with motion-compensated prediction has proven to be an efficient approach in video compression. However, when dealing with spatially neighboring blocks in uniformly displaced regions, quadtree-based partitioning may lead to redundant sets of transmitted motion parameters. This paper proposes and describes a simple but efficient block merging algorithm that aims at removing those redundancies by using only a single parameter set for a whole motion-compensated region of contiguous blocks. Simulation results show that our proposed merging technique works more efficiently than the conceptually similar direct mode as, e.g., specified in H.264/AVC. Due its efficiency and simplicity, our proposed merging approach has been adopted into the first test model of the high efficiency video coding (HEVC) standardization project, as currently pursued by ITU-T VCEG and ISO/IEC MPEG.