On a Highly Efficient RDO-Based Mode Decision Pipeline Design for AVS

Rate distortion optimization (RDO) is the best known mode decision method, while the high implementation complexity limits its applications and almost no real-time hardware encoder is truly full-featured RDO based. In this paper, first, a full-featured RDO-based mode decision (MD) algorithm is presented, which makes more modes enter RDO process. Second, the throughput of RDO-based MD pipeline is thoroughly analyzed and modeled. Third, a highly efficient adaptive block-level pipelining architecture of RDO-based MD for AVS video encoder is proposed which can achieve the highest throughput to alleviate the RDO burden. Our design is described in high-level Verilog/VHDL hardware description language and implemented under SMIC 0.18- μm CMOS technology with 232 K logic gates and 85 Kb SRAMs. The implementation results validate our architectural design and the proposed architecture can support real time processing of 1080P@30 fps. The coding efficiency of our adopted method far outperforms (0.57 dB PSNR gain in average) the traditional low-complexity MD (LCMD) methods and the throughput of our designed pipeline is increased by 11.3%, 19% and 17% for I, P and B frames, respectively, compared with the existed RDO-based architecture.