一种基于参考质量的帧间自适应加权预测
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摘要
帧间双向预测在目前的主流视频编码标准中扮演着重要的角色,该技术主要利用时域相关性去除图像间的冗余信息。帧间双向加权预测仅对两个运动补偿块做简单的加权平均(即权值为0.5)。但当参考帧与编码帧之间的亮度发生剧烈变化,或由于诸如量化等因素导致生成预测块的质量不同时,采用现有的方法将会产生严重的失真。因此文中提出了基于参考质量的帧间自适应加权预测方法来解决上述问题。在本方案中,当前编码块参考的质量越好,则分配的权值越大,反之亦成立。实验结果显示,在编解码复杂度可接受的情况下,采用两种方法计算的权值在随机接入(RA)配置下和低时延B帧(LDB)配置下,相比于JEM5.0.1参考软件的基准平均码率分别节省约0.25%和0.3%。
In modern video codecs,bi-prediction technique plays a significant role for removing temporal redundancy by exploiting temporal correlations between pictures.The bi-prediction signal is formed simply by averaging two uni-prediction signals using a fixed weight value 0.5.However,it will produce serious distortion in some condition that illumination changes rapidly from one reference picture to another or the prediction quality of one motion-compensated prediction block may differ from the other due to the factors such as quantization.To solve the above problems,an adaptive weighted bi-prediction method based on reference quality was proposed in this paper.In this scheme,the greater weight value will be assigned to the reference block if the quality of the reference block is better,and vice versa.The simulation results show that compared with JEM5.0.1,the proposed weighted bi-prediction can achieve about 0.25% and 0.3% Bj⌀ntegaard delta(BD) bitrate savings on average under random access main(RA) and low-delay B main(LDB) confi-gurations,respectively,while the increased encoding and decoding complexities are moderate.
In modern video codecs,bi-prediction technique plays a significant role for removing temporal redundancy by exploiting temporal correlations between pictures.The bi-prediction signal is formed simply by averaging two uni-prediction signals using a fixed weight value 0.5.However,it will produce serious distortion in some condition that illumination changes rapidly from one reference picture to another or the prediction quality of one motion-compensated prediction block may differ from the other due to the factors such as quantization.To solve the above problems,an adaptive weighted bi-prediction method based on reference quality was proposed in this paper.In this scheme,the greater weight value will be assigned to the reference block if the quality of the reference block is better,and vice versa.The simulation results show that compared with JEM5.0.1,the proposed weighted bi-prediction can achieve about 0.25% and 0.3% Bj⌀ntegaard delta(BD) bitrate savings on average under random access main(RA) and low-delay B main(LDB) confi-gurations,respectively,while the increased encoding and decoding complexities are moderate.
引文
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[2] CHEN J,CHEN Y,KARCZEWICZ M,et al.Coding tools investigation for next generation video coding:ITU-T SG16-C806[S].2015.
[3] KARCZEWICZ M,CHEN J,CHIEN W J,et al.Study of coding efficiency improvements beyond HEVC:MPEG doc.m37102[S].2015.
[4] CHOI K,ALSHINA E,ALSHIN A,et al.Information on coding efficiency improvements over HEVC for 4K content:MPEG doc.m37043[S].2015.
[5] YIN P,TOURAPIS A M,BOYCE J.Localized weighted prediction for video coding[C]//Proceedings of IEEE International Symposium on Circuits and Systems.New York:IEEE Press,2005:4365-4368.
[6] LIU H,CHEN Y,CHEN J,et al.Local Illumination Compensation:VCEG-AZ06[S].2015.
[7] CHEN C C,XIU X,HE Y,et al.EE3:Generalized bi-prediction:JVET-D0102[S].2016.
[8] YUAN Y,KIM I K,ZHENG X Z,et al.Quadtree Based Non- square Block Structure for Inter Frame Coding in High Efficiency Video Coding[J].IEEE Transactions on Circuits and Systems for Video Technology,2012,22(12):1707-1718.
[9] UGUR K,ALSHIN A,ALSHINA E,et al.Motion Compensated Prediction and Interpolation Filter Design in H.265/HEVC[J].IEEE Journal of Selected Topics in Signal Processing,2013,7(6):946-956.
[10] CHEN Y,MUKHERJEE D.Variable block-size overlapped block motion compensation in the next generation open-source video codec[C]//Proceedings of IEEE International Conference on Image Processing.New York:IEEE Press,2017:938-942.
[11] LI L,LI H,LV Z,et al.An affine motion compensation framework for high efficiency video coding[C]//Proceedings of IEEE International Symposium on Circuits and Systems. New York:IEEE Press,2015:525-528.
[12] ALSHIN A,ALSHINA E.Bi-directional Pptical Flow for Fu- ture Video Codec[C]//Proceedings of Data Compression Conference. New York:IEEE Press,2016:83-90.
[13] SUEHRING K,LI X.JVET common test conditions and software reference configurations:JVET-B1001[S].2016.
[14] BJONTEGAARD G.Calculation of average PSNR difference between RD-curves:VCEG-M33[S].