H.264码率控制算法研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
H.264/AVC是国际电信联盟电信标准化部门ITU-T(ITU Telecommunication Standardization Sector)和移动图像专家组MPEG(Moving Picture Experts Group)联合成立的联合视频小组JVT(Joint Video Expert Team)于2003年3月正式发布的新一代视频编码国际标准,其目标是在保证图像质量的同时进一步提高数据压缩效率。H.264/AVC有着非常好的压缩性能,它将在数字电视广播、视频实时通信以及网络视频流媒体传递等领域发挥重要作用。
     论文首先在介绍视频编码技术的发展背景及现状的基础上,详细分析和讨论了H.264/AVC视频编码标准,并对H.264/AVC的特点、应用以及H.264编码标准中的帧内预测、帧间预测、整数变换、量化、熵编码和去方块滤波器等关键技术做了较为详细的分析和研究。
     其次,论文介绍了码率控制算法的基本原理。码率控制的目的就是控制输出码率,使输出码流更加平稳,从而更加有效地利用网络带宽,同时尽可能达到好的平稳的图像质量。论文介绍了RM8、TM5、VM8、TMN8等几种经典的码率控制算法以及基于拉格朗日优化算法的H.264编码控制模型,随后深入分析并讨论了H.264/AVC视频编码标准中使用的码率控制算法JVT-G012。JVT-G012码率控制算法主要由三步组成:目标比特分配;根据所分配的目标比特计算相应的量化参数;编码完成后对模型参数进行更新。
     论文重点研究了JVT-G012码率控制算法,并深入讨论了其存在的三点不足:一、JVT-G012码率控制算法中根据前一个GOP中所有P帧的量化参数均值来计算当前GOP中I帧的量化参数,对I帧的码率控制过于简单;二、JVT-G012算法仅根据缓冲区的剩余比特数对P帧进行比特分配,对P帧的比特分配不够精确;三、JVT-G012算法未考虑到视频序列中的场景切换问题,导致在场景切换处图像质量急剧下降,容易造成缓冲区溢出。针对上述三点不足之处,论文分别进行了处理:一、论文提出一种根据前一个GOP中I帧的复杂度比例关系计算I帧的量化参数,与JVT-G012算法中计算的I帧量化参数加权处理,对I帧进行较为精确的控制。二、根据输出缓冲区状态、P帧的图像复杂度以及P帧在GOP中的位置对P帧进行比特分配。三、针对JVT-G012算法未考虑到场景切换的缺陷,论文提出了一种基于场景切换的处理算法:根据像素点亮度分量绝对差值和均值法检测视频序列中是否发生场景切换;如果序列中有场景切换发生,使用论文提出的一种自适应GOP结构与长度的场景切换处理算法进行处理。
     最后,在JM8.6平台下,对JVT-G012算法与论文提出的算法分别进行实验验证。实验结果表明,改进后的算法能够更加精确控制输出码率,图像的PSNR(Peak Signal to Noise Ratio)也获得了一定的提高,同时改进后的算法能够有效的检测与处理视频序列中的场景切换,稳定了场景切换点后的图像质量。
H.264/AVC is a new generation video coding compression standard. It was developed by JVT (Joint Video Expert Team) which was joined by ITU-T(ITU Telecommunication Standardization Sector) and MPEG(Moving Picture Experts Group) in March 2003. The goal of H.264/AVC is to ensure image quality and improve the compression efficiency. H.264/AVC has a very good compression performance. It will play an important role in the fields of digital TV broadcasting, real-time communication and network streaming meida.
     Firstly, the H.264/AVC coding standard was detailedly analyzed and discussed based on the introduction of the video encoding technology background and research status. The features and application of H.264/AVC and key techniques in H.264 which include intra-prediction, inter-prediction, integer transform, quantization, entropy coding and block filtering are detailedly analyzed.
     Secondly, the basic principle of rate control algorithm was introduced in this dissertation. The purpose of rate control is to control output bit rate, so that network bandwidth is used more efficiently and image quality will be better and more stable. We introduced several classic rate control algorithms such as RM8, TM5, VM8 and TMN8. H.264 coding control model based on the Lagrangian optimization algorithm was introduced, and the rate control algorithm of JVT-G012 used in H.264/AVC coding standard was deeply analyzed and discussed in the following. JVT-G012 rate control algorithm is composed mainly of three steps: target bit allocation; calculate the corresponding quantization parameter according to the allocated target bit; update the model parameters after the image was compressed.
     This dissertation focuses on the JVT-G012 rate control algorithm. There are three disadvantages of JVT-G012 algorithm have been discussed. (1). JVT-G012 rate control algorithm uses the P-frame’s quantization parameters of the previous GOP to calculate the I-frame’s quantization parameter in the current GOP, so rate control of the I-frame is too simple. (2). JVT-G012 algorithm is only based on the remaining number of bits of the buffer to allocate bits of P-frame, so the bit allocation of the P-frame was not sufficiently precise. (3). Because JVT-G012 algorithm does not take the problem of scene change in the video sequence into account, the image quality can decline sharply and the buffer can overflow easily when scene change occurred. To solve these problems, we dealt with them separately. (1). We calculate QP of the I-frame by weighting the QP which was calculated by using the proportion of I-frame’s complexity in the previous GOP and the QP which was calculated by H.264 rate control algorithm, to control the I-frame’s QP precisely. (2). We allocate bit of the P-frame based on the output buffer status, the image complexity of the P-frame and the position of the P-frame in the GOP. (3). Because JVT-G012 algorithm does not take the problem of scene change into account, we propose a rate control algorithm based on scene change in the dissertation. Firstly, we detect scene change in the sequence by using the mean absolute difference of pixel brightness component. If scene change was detected, we use an adaptive GOP structure and length of the scene change processing algorithm to process the scene change which was occurred.
     Finally, by using JM8.6 platform, the JVT-G012 algorithm and the proposed algorithm in the dissertation were carried out experimental verification respectively. Experimental results show that the improved algorithm can control the output bit rate more accurately, the PSNR of the image has also increased while the improved algorithm can effectively detect and deal with the scene change in the video sequences, and the image quality after the scene change has also been stabilized.
引文
[1] ISO/IEC JTC1/SC29/WGII, ISO/IEC, MPEG-1 Committee Draft, CD11172: Information Technology. Dec. 1991
    [2] ISO/IEC JTC1/SC29/WGII, ISO/IEC, MPEG-2 Committee Draft, CD13818: Information Technology. Dec. 1993
    [3] ISO/IEC/ITC1/SC29/WGII, ISO/IEC, Coding of Audio-Visual Objects-Part2: Visual, ISO/IEC 14496-2(MPEG-4 Visual Version 1), Apr 1999.
    [4] ITU-T, Recommendation H.261: Video Codec for Audiovisual Services at px64 kbit/s, Mar 1993.
    [5] ITU-T, Recommendation H.263: Video Coding for Low Bit Rate Communication, ITU-T Recommendation H.263 Draft, July 1995.
    [6] Joint Video Team(JVT) of ISO/IEC MPEG and ITU-T VCEG Draft ITU-T recommendation and final draft international standard of joint video specification(ITU-T Rec.H.264/ISO/IEC 14496-10AVC), JVT G050, Pattaya, Mar 2003.
    [7] Barry G. Haskell, Paul G. Howard, Yann A. Lecun, Image and Video Coding-Emerging standards and Beyond[J], IEEE Transactions On Circuits and Systems for Video Technology,1998,18(7):814-837.
    [8] ITU-T Recommendation H.262,“Information technology-Generic coding of moving pictures and associated audio information: Video”, 2000
    [9] Sikora, T. MPEG digital video-coding standards[J]. IEEE Signal Processing Magazine, vo1.14, no.5, pp.82-100, Sep, 1997.
    [10] B. Girod, U.Hom, B. Belzer. Scalable video coding with multiscale motion compression and unequal error protection[J]. Proc. Of Symp. Multimedia Communications and Video Coding, New York, 475-482, Oct. 1995.
    [11] A. Tamhanker, K. R. Rao. An overview of H.264/MPEG-4 Part 10[A]. The 4th EURASIP Conference focused on Video/Image Processing and Multimedia Communications(Keynote Speech). 1:1-51, July 2003.
    [12] T. Wiegand, G. J. Sullivan, G.Bjontegarrd and A. Luthra. Overview of the H.264/AVC Video Coding Standard[A], IEEE Transacation on Circuits and Systems. Vol, 13, July 2003, 560-576
    [13]黄铁军等,数字音视频编解码标准(AVS)工作组发布视频标准草案,http://www.avs.org.cn/.
    [14]马思伟, AVS视频编码技术回顾与应用展望[J] ,信息技术快报,Vol.3.No.10,Oct.2005
    [15] T.Chiang and Y. Q. Zhang. A new rate control scheme using quadratic rate distoration model[J]. IEEE Trans. Circuits Syst, Video Technol, pp. 246-250, Feb 1997
    [16] J.Ribas-Corbera and S. Lei. Rate control in DCT video coding for low-delay communications[J]. IEEE Trans. Circuits Systs. Video Technol, vol.9, pp. 172-185, Feb 1999
    [17] A. Vetro, H.F.Sun, and Y. Wang. MPEG-4 rate control for multiple video objects[J]. IEEE Trans. Circuits Syst, Video Technol, vol 9, pp. 186-199, Feb 1999
    [18] S. W. Ma, W. Gao and Y. Lu, Rate Control on JVT Standard, JVT D030, 4th Meeting, Klagenfurt, Australia, July, 2002. 100-111
    [19] JianFeng Xu and Yun He, A Novel Rate Control for H.264[J], IEEE int. Sysmp. Circuits Syst. 2004. vol.3:809-812
    [20] S. W. Ma, W. Gao and Y. Lu and H. Q. Lu. Proposed Draft Description of Rate Control on JVT Standard, JVT-F086[S]. 6th meeting, December, 2002.5-13
    [21]毕厚杰.新一代视频压缩编码标准-H.264/AVC[M].人民邮电出版社
    [22] G.Bjontegarrd, K. Lillevold, Context-adaptive VLC Coding of Coefficients[S], JVT-C028, Faiefax, 2002-5.
    [23] Detlev Marpe, Heiko Schwarz, Thomas Wiegand, Context-Based Adaptive Binary Arithmetic Coding in the H.264/AVC Video Compression Standard[J], IEEE Transactions on CSVT, 2003, 13(7):620-636.
    [24]余兆明,查日勇,黄磊,周海娇.图像编码标准H.264技术[M].人民邮电出版社.
    [25]胡寿松,自动控制原理[M],北京:国防工业出版社,1990
    [26] MPEG-2 Video Test Model 5[S]. ISO/IEC/JTC1/SC29/WG11, MPEG94/457 1993. 10-30
    [27] J. W.Lee. Target Bit Matching for MPEG-2 Video Rate Control[R], Processing of Tencon 1998. New Delhi, India, 1998, vol.1:66-99
    [28] T.Chiang and Y. Q. Zhang. A New Rate Control Scheme Using Quadratic Rate Distortion Model[J]. IEEE Transactions on Circuits and Systems for Video Technology, Feb. 1997, vol7:246-250
    [29] Video Codec. Test Model Near-Term, TMN8[S]. ITU-T/SG16/VCEG/Q15 A59 Portland, USA, Jun 1997. 66-68
    [30] Z. He,ρ? domain rate-distortion analysis and rate control for visual coding and communications[J], Dissertation of University of California Santa Barbara, 2001-6.
    [31] W. Ding, B. Liu. Rate Control of MPEG Video Coding and Recording byRate-Quantization Modeling[J]. IEEE Trans. Circuits and Syst. For Video Technology, Feb. 1996, 6(1):12-20
    [32] Ning Wang, Yun He. A new rate control strategy for H.264[J], ICICS-PCM, Singapore, 2003, 12:1370-1374
    [33] T. Chiang and Y. Q. Zhang. A New Rate Control Scheme Using Quadratic Rate Distortion Model[J]. IEEE Transactions on Circuits and Systems for Video Technology, Feb. 1997, vol7:246-250
    [34] S. Sethurman, R. Krishnamurthy, Model based multi-pass macroblock-level rate control for visually improved video coding, Proc Workshop and Exhibition on MPEG-4, 2001:59-62
    [35] Z. G. Li, F. Pan, K. P. Lim, G. Feng, X. Lin, S. Rahardja, Adaptive basic unit layer rate control for JVT[R], in JVT 7th Meeting, Pattaya II, Thailand, Mar. 2003. Doc:JVT-G012-r1.
    [36] Joint Video Team(JVT) of ISO/IEC MPEG and ITU-T VCEG Document JVT-B118R2[S], 2002-03-25.
    [37] Z. G. Li, Lin Xiao, C. Zhu and Pan Feng. A Novel Rate Control Scheme for Video Over the Internet[J]. In Proceedings ICASSP 2002, Florida, USA, 2065-2068, May 13-17, 2002
    [38] H. J. Lee and T. H. Chiang and Y. Q. Zhang. Scalable Rate Control for MPEG-4 Video[J]. IEEE Trans. Circuits Syst. Video Technology, 10:878-894, 2000.
    [39] A. Vetro, H. Sun and Y. Wang. MPEG-4 rate control for multiple video objects[J]. IEEE Trans. Circuits Syst. Video Technology, 9:186-199, 1999.
    [40]段大高,李文正,莫倩,毛明毅.一种改进的H.264码率控制算法[J].微电子学与计算机,2008,25(6):90-93.
    [41]袁武,林守勋,牛振东,罗海勇,张勇东. H.264/AVC码率控制优化算法[J].计算机学报,2008,31(2):329-339.
    [42] W. A. C. Fernando, C. N. Canagarajah, D. R. Bull, Fade-in and Fade-out Detection in video sequence using Histograms[J], ISCAS 2000-IEEE International Symposium on Circuit and Systems, May 28-31, 2000, Geneva, Switzerland
    [43] Yeo, B. L, Rapid Scene Analysis on Compressed Video[J], IEEE Transcations on Ciucuit and System for video technology, Vol 5, No 6, pp.533-544, December 1995
    [44] Feature-Based Algorithms for Detecting and Classifying Scene Breaks[A], 4th ACM Intl. Conference and Multimedia, San Francisco, California, November 1995
    [45] Alattar, A. M, Detecting Fade Regions and Uncompressed Video Sequence[J], pp.3025-3028, ICASSP, 1997
    [46] Fernando, W. A. C, Canagarajah, C. N, Bull, D. R, Automatic Deteciton of Fade-in and Fade-out in Video Sequence[A], Volume IV, ISCAS, pp.255-258, 1999
    [47] Fernando, W. A. C, Canagarajah, C. N, Bull, D. R, Video Segmentation and Classification for Content Based Storage and Retrival Using Motion Vectors[A], Storage and Retrieval for Image and Video Databases VII, SPIE, pp.687-698, 1999
    [48] Fernando, W. A. C, Canagarajah, C. N, Bull, D. R, Sudden Scene Change Detection in MPEG-2 Video Sequence[J], in Proc of IEEE International Workshop on Multimdia Signal Processing(MMSP), pp.259-264, 1999
    [49] W. A. C Fernando, Modeling of Fading and Dissoving in Video Sequence for Gradual Scene Change Detection[A], to be appeared in Proc. Of the Second International Symposium on Communication and Information Technology, Pattaya, Thailand, October 2002
    [50] Jiang M. Ling N. On enhancing H.264/AVC video rate control by PSNR-based frame complexity estimation[J]. IEEE Trans on Consumer Electronics, 2005; 1(51):281-286
    [51] Lee C, Lee S, Oh Y, et al Real-time H.264 rate control for scene-changed video at low bit rate[A]. ICCE 2007; 2007:1-2
    [52] Lee J, Shin I, Park H. Adaptive intra-frame assignment and bit-rate estimation for variable GOP length in H.264[J]. IEEE Trans on Circuits and Systems for Video Technology, 2006:10(16):1271-1279
    [53]余越,周健,王贻良等.一种场景切换检测及自适应码率控制方法[J].通信学报,1999,20(5):50-55.
    [54]余成伟,陆建华,郑君里.基于场景切换的H.264码率控制技术[J].清华大学学报,2007;7(47):1133-1136

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700