Complexity Reduction and Performance Improvement for Geometry Partitioning in Video Coding

Geometry partitioning for video coding involves establishing a partition line boundary within each block-shaped region and applying motion-compensated prediction to the two sub-regions created by the partition line. This paper presents techniques for enhancing the effectiveness and reducing the complexity of geometry partitioning schemes. A texture-difference-based approach is described to simplify the process of selecting the partition lines. Applying this approach together with a described skipping strategy for blocks with uniform texture can achieve a 94% reduction of encoding time while retaining a similar rate-distortion (R-D) performance to the full-search partitioning approach, when implemented for wedge-based geometry partitioning (WGP) in the context of H.264/MPEG-4 AVC JM 16.2. A bit rate improvement of approximately 6% is shown relative to not using geometry partitioning. For further R-D improvement, we describe a background-compensated prediction scheme to reduce the number of overhead bits used for motion vectors. Additionally, for systems in which high-quality depth maps are available, we incorporate depth map usage into the described approaches to generate a more accurate partitioning. Using these approaches with object-boundary-based geometry partitioning can achieve about 9% bit rate savings relative to using WGP, while keeping a similar computational complexity to the described complexity-reduced WGP.