Hybrid Laplace Distribution-Based Low Complexity Rate-Distortion Optimized Quantization
Hybrid Laplace Distribution-Based Low Complexity Rate-Distortion Optimized Quantization
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基于混合拉普拉斯分布的低复杂度率失真优化量化
DOI：
10.1109/tip.2017.2703112
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发表时间：
2017
影响因子：
10.6
通讯作者：
Gao Wen
中科院分区：
文献类型：
--
作者：
Cui Jing;Wang Shanshe;Wang Shiqi;Zhang Xinfeng;Ma Siwei;Gao Wen
率失真优化量化（RDOQ）是一种高效的编码器优化方法，其在提高高效视频编码（HEVC）编解码器的率失真（RD）性能方面起重要作用。然而，RDOQ的上级性能是以两个阶段RD最小化中的高计算复杂度成本为代价来实现的，这两个阶段RD最小化包括确定每个变换系数的可用候选中的最佳量化级别以及确定具有最小总成本的变换单元的最佳量化系数，以软优化量化系数。为了降低HEVC中RDOQ算法的计算成本，我们通过对具有混合拉普拉斯分布的变换系数的统计进行建模，提出了一种低复杂度的RDOQ方案。以这种方式，基于系数分布建立专门设计的块级速率和失真模型。因此，可以通过优化整个块的RD性能来直接确定最佳量化级别，同时最终可以避免复杂的RD成本计算。大量的实验结果表明，在RD性能下降约0.3%-0.4%的情况下，所提出的低复杂度RDOQ算法能够减少约70%的量化时间，与HEVC中的原始RDOQ实现相比，平均减少高达17%的总编码时间。
Rate distortion optimized quantization (RDOQ) is an efficient encoder optimization method that plays an important role in improving the rate-distortion (RD) performance of the high-efficiency video coding (HEVC) codecs. However, the superior performance of RDOQ is achieved at the expense of high computational complexity cost in two stages RD minimization, including the determination of optimal quantized level among available candidates for each transformed coefficient and the determination of best quantized coefficients for transform units with the minimum total cost, to softly optimize the quantized coefficients. To reduce the computational cost of the RDOQ algorithm in HEVC, we propose a low-complexity RDOQ scheme by modeling the statistics of the transform coefficients with hybrid Laplace distribution. In this manner, specifically designed block level rate and distortion models are established based on the coefficient distribution. Therefore, the optimal quantization levels can be directly determined by optimizing the RD performance of the whole block, while the complicated RD cost calculations can be eventually avoided. Extensive experimental results show that with about 0.3%−0.4% RD performance degradation, the proposed low-complexity RDOQ algorithm is able to reduce around 70% quantization time with up to 17% total encoding time reduction compared with the original RDOQ implementation in HEVC on average.