融合空域相关和率失真代价的HEVC帧内编码算法  

An Intra Coding Algorithm for HEVC Based on Spatial Correlation and Rate Distortion Cost

作　　者：诸志龙[1,2] 王凤随[1,2] ZHU Zhilong WANG Fengsui(College of Electrical Engineering, Anhui Polytechnic University, Wuhu, Anhui 241000, China Anhui Key Laboratory of Detection Technology and Energy Saving Devices, Wuhu, Anhui 241000, China)

机构地区：[1]安徽工程大学电气工程学院,安徽芜湖241000 [2]安徽省检测技术与节能装置省级重点实验室,安徽芜湖241000

出　　处：《昆明理工大学学报（自然科学版）》2017年第1期44-52,共9页Journal of Kunming University of Science and Technology(Natural Science)

基　　金：安徽省检测技术与节能装置省级重点实验室开放基金项目(1506c085002);安徽省自然科学研究重点项目(KJ2015A071);安徽工程大学引进人才科研启动项目(2014YQQ006)

摘　　要：新一代视频编码标准HEVC采用基于编码单元(CU)四叉树递归的分割结构,与上一代视频压缩标准H.264/AVC的高档次相比,最高能够节省50%的比特数.然而,由于HEVC增加了更多的划分块尺寸和预测模式,导致了编码复杂度急剧上升.因此,本文提出了一种融合空域相关信息和率失真代价值的帧内编码模式.本文首先根据各序列的不同运动和纹理特性,通过寻找编码单元深度预测值和实际值之间的误差,从训练帧得到最佳的加权系数,最后决定编码单元是否继续分割;其次,将每个编码单元划分为四个子单元,计算每层的率失真代价总和,据此计算出率失真代价的阈值,按照每秒训练两帧情况更新阈值,以此阈值决定该编码单元是否继续分割.实验结果表明,本文算法相对于原始编码器,平均可以降低48%的编码复杂度,平均比特率BDBR仅增加0.91%,平均峰值信噪比BDPSNR仅下降0.05 d B.The next generation video coding standard HEVC（ High Efficiency Video Coding） has achieved up to approximately 50 % bit rate saving compared with former standard H. 264/AVC due to its recursive quad-tree partitioning structure based on CU（ Coding Unit）. However,the encoding complexity of HEVC increases dramatically with the introduction of more partition sizes and prediction modes. Therefore,this paper proposes an intra coding algorithm based on the fusion of spatial correlation information and rate distortion cost. Firstly,based on the spatial correlation information,different motion and texture characteristics of each sequence are analyzed,and the optimal weighting coefficients can be obtained from training frames by calculating errors between the predicted and actual values of CU depth. Then the need for CU segmentation is decided. Secondly,based on the rate distortion cost,each CU is divided into four sub units and the sum of rate distortion cost of each layer is calculated. Based on the calculated results,the threshold of rate distortion cost is calculated and updated by two frames per second. Whether the CU needs further segmentation is determined by the threshold. The experiment results demonstrate that the proposed method can reduce encoding time by 48 % on average,with only 0. 91 % BDBR increase and 0. 05 d B BDPSNR loss compared with the original HEVC encoder.

关 键 词：HEVC 编码单元 帧内编码 空域相关 

分 类 号：TN919.81[电子电信—通信与信息系统]