【作者】 廖顺和；

【导师】 乐嘉锦；

【作者基本信息】 东华大学 ， 计算机应用技术， 2008， 硕士

【摘要】 城市轨道交通视频监控是城市公共安全领域的重要保障手段,也是视频监控领域的一个研究热点。随着软硬件技术的不断进步,视频采样技术、视频压缩编码技术和视频传输技术的发展,城市轨道交通视频监控技术也得到了长足进步。H.264是国际标准化组织(ISO)和国际电信联盟(ITU)共同制定的新一代视频编码标准,它采用了一系列的新技术,显著的提高了编码效率,成为近年来最为高效的视频压缩编码标准。为了在有限的网络带宽、延时和缓存下取得较好的图像质量,必须采用适当的策略来控制编码器,将编码器的码率输出控制在一定的范围内,码率控制技术随之成为视频编码的关键技术之一,也是实现城市轨道交通视频监控高质量和高实时性要求的解决方法。本文在探讨了城市轨道交通视频监控的发展现状后对于其所涉及到的关键技术进行了研究,重点介绍了视频压缩编码技术中的H.264编码标准,深入分析了码率控制的基本原理,讨论了视频编码中产生码率波动的原因,介绍并总结了当前主流编码标准的码率控制算法,其中对H.264的码率控制算法进行了详细分析,对GOP层、帧层和基本单元层三个层次的码率控制进行分析,完全剖析了H.264码率控制算法的原理和步骤。在现有的H.264码率控制技术研究成果的基础上,结合城市轨道交通视频监控的实际需求,本文提出了一种基于线性回归的H.264码率控制算法。该算法利用线性回归的思想建立了QP－PSNR的线性模型和R－ρ－Eρ－EQP－QP线性模型,可以为视频序列中的工帧和P帧快速的计算出更为精确的量化参数QP,大大简化了计算的复杂度,克服了现有H.264码率控制算法在运算效率上的不足,实现更为有效的码率控制。实验结果表明,与现有的两种H.264码率控制算法相比,基于线性回归的算法在码率错误估计、视频质量和缓冲区占有率等方面都凸现出优势,满足轨道交通视频监控中的高质量和高实时性的要求。在以上的理论基础上,论文提出了城市轨道交通视频监控的总体设计方案,为轨道交通视频监控的实现给出了系统设计和设备分配的参考方案。结合方案设备选型实现了一个基于线性回归码率控制算法的视频监控系统,为城市轨道交通视频监控系统的研究实现做了有目的的尝试,以此证明方案的可行性和基于线性回归码率控制算法的有效性。更多还原

【Abstract】 Video Surveillance for urban rail transportation is an important way for the Urban public security areas, is also a hotpot of research in the Video Surveillance area. With the continuous improvement of the hardware and software , the development of Video sampling technology, video compression and coding technology and video transmission technology, Video Surveillance for Urban rail transportation technology has also developed rapidly. As a new generation video coding standard developed jointly by ISO and ITU. H.264 employs a series of new technologies, improves video coding efficiency greatly, and has been nominated to be the most efficient video coding standard in recent years as a result. To achieve better image quality under the channel bandwidth, time-lapse and buffer limitation, appropriate strategies must be adopted to control the rate of encoder’s output into a certain range.Therefore, rate control has become one of the key techniques of video coding, also is the Solution to achieve high quality video and high real-time requirement of Video Surveillance for Urban rail transportation.After discuession about the development status of video surveillance for urban rail transportation, the Related key technologies are analyzed, the video coding standard of H.264 is introduced, the basic principle of rate control is discuessed deeply, the reasons that cause the rate variance are analyzed, and the algorithms of several video coding standards are also reviewed ans summarized in this dissertation. Based on the existing research results of the rate control technique for H.264, considered about the actual requirement of videosurveillance for urban rail transportation, a rate control algorithm based on the linear regression for H.264 is proposed. With the theory of linear regression, the algorithm establishes two linear models of QP-PSNR and R-ρ-E_ρ-E_QP-QP in order to calculate more precise quantitative parameters, overcomes the limitation of existing algorithms in calculation efficiency, and achieves more effective rate control. The experimental results show that, the algorithm based on the linear outperforms the existing rate control algorithms for H.264 for rate estimation error ,video quality and buffer occupancy.With the theory discuessed above , an overall design of video surveillance for urban rail transportation is proposed, and a video surveillance system based on the linear regression is eastablished for a try, in order to prove the feasibility of the design and the availability of the rate control algorithm based on linear regression.更多还原