High throughput VLSI architecture for HEVC SAO encoding for ultra HDTV

This paper presents a high performance, silicon area efficient, and software configurable hardware architecture for sample adaptive offset (SAO) encoding. The paper proposes a novel architecture consisting of single largest coding unit (LCU) stage SAO operation, unified data path for luma and chroma channels, add-on external interfaces on frame level statistics collection units to allow fine control over the parameter estimation process, flexible rate control and artifact avoidance algorithms. The unified data path consists of 2D-block based processing with 3 pipeline stages for statistics generation and multiple offset rate-distortion cost estimation blocks for high performance. The proposed design after placement and routing is expected to take-up approximately 0.15 mm2 of silicon area in 28nm CMOS process. The proposed design at 200 MHz supports 4K Ultra HD video encoding at 60fps. Simulation experiments have shown average bit-rate saving of up to 4.3% with in-loop SAO filtering and various encoder configurations.