视频编码率失真优化技术研究综述

Overview of Rate-Distortion Optimization for Video Coding

率失真优化技术能有效地提升编码器的压缩性能,是视频编码领域重要的研究内容.本文综合论述了基于拉格朗日乘子的率失真优化方法,从独立率失真优化、依赖率失真优化和码率控制中的比特分配等几方面归纳和分析最新研究进展.首先,通过形象的举例解释了约束优化问题通过拉格朗日乘子法转换为非约束优化问题,并根据相关文献分析拉格朗日乘子与量化参数的关系.其次,分析了编码过程中存在的率失真依赖性,并分类讨论近年提出的依赖率失真优化方法.然后,简要介绍了率失真依赖关系在码率控制比特分配中的影响.最后通过分析比较不同率失真优化技术的特征和性能,提出当前面临的挑战和值得进一步探索的工作.

Rate-distortion optimization(RDO)can effectively improve the compression performance for encoders,which is an important topic in video coding.In this paper,the Lagrange multiplier based RDO method is reviewed comprehensively from several aspects including independent RDO,dependent RDO,bit allocation for rate control,etc.First,an example is employed to explain how the constrained optimization problem is converted into an unconstrained optimization problem based on the Lagrange multiplier method,and the relationship between Lagrange multiplier and quantization parameter is analyzed according to relevant references.Second,the rate-distortion dependencies in the process of video coding are analyzed,and the dependent RDO methods presented in recent years are classified and discussed.Third,the effect of the rate-distortion dependencies on bit allocation for rate control is discussed.Finally,the features and performance of different RDO methods are tabulated for analysis and comparison,and the existing challenges and the research works deserving further exploration are presented.