基于熵编码加密的MPEG视频加密算法研究

针对现存算法在安全性和压缩比方面的不足 ,提出一种基于熵编码加密的 MPEG视频加密算法 .此算法在熵编码过程中 ,通过加密码字在 Huffm an编码表中的序号 ,实现加密编码 .与置乱 Huffman编码表和置乱 Huffman树方法相比较 ,具有更大的置乱空间 ,具有更高的安全性 .实验表明 ,此算法对压缩比的影响比 DCT系数加密算法小 ,计算复杂度低、速度快 ,适合用于视频的实时安全编码中     

视频实时加密算法的研究与实现

提出一种新的视频实时加密算法RMVEA。RMVEA建立在数字多媒体实时动态系统上,独立于任何视频压缩算法,为实时数字视频提供高强度、高速度的加密。实验结果表明该锋法在基本不增加视频编码器负载及系统延时的情况下,能有效解决视频压缩率与密钥选择自由度的矛盾。     

基于混沌的视频压缩与加密方法研究

针对多媒体流的压缩与加密技术,分析了很多算法在安全性和实时性上存在的缺点。对现有多种代表算法做出了比较,将一些算法的优点与混沌伪随机序列发生方法相结合,提出了一种适于软件实现的安全性高、速度快的加密方法,并分别针对MPEG2视频压缩算法和基于小波变换的视频压缩算法的特性进行加密处理。实验结果表明,MPEG2混沌加密算法可实现实时处理,基于小波变换的混沌加密算法能达到较高压缩比。     

一种基于格雷码变换和M序列异或的MPEG视频加密算法

在多数的视频加密算法中,视频加密后的数据流会显著增大,因为这些算法没有考虑到视频编码特点,导致传输吞吐率的下降。结合MPEG编码特点,利用格雷码和自然二进制码相互转换的易生成性,以及M序列良好的随机特性,提出一种快速视频加密算法。算法先在宏块DCT变换之前进行空域置乱运算,然后对Z字型扫描后的DC和AC系数符号位进行异或运算。加密后的数据大小不变,且加密速度快,两种算法结合安全性高。     

视频加密算法及其发展现状

根据加密算法中压缩过程和加密过程关系的不同，将算法分为三类进行综述：直接加密算法、选择性加密算法和具有压缩编码功能的加密算法．在分别分析了它们的安全性、计算复杂性和压缩比等特点的基础上，给出了它们各自适合的应用范围，并且对视频加密算法的未来作了展望．     

一种保密性可分级的视频加密方案

在不同的应用场合对视频信息有不同级别的安全性需求。分析了现有的两种可分级视频加密方案,进而基于视频的信源特征,提出了一种不改变码流格式的保密性可分级的视频加密方案。方案定义了视频码流中的几种关键信息作为加密的对象,然后通过选择加密信息类型的不同组合来实现不同的保密级别。试验结果表明该加密方案不改变视频码流格式、不影响视频的实时传输、不增加额外带宽,根据选用不同的密级可以适用不同安全性需求的应用场合。     

基于MPEG4的网络视频流加密技术的研究

根据网络视频流安全传输的要求和MPEG4视频编码的特点,该文提出了一种基于Logistic混沌映射的视频加密算法,在编码过程中利用混沌序列对视频数据在频域进行加密。该文将该算法实现在MPEG4的编解码器XVID中,在保证数据安全传输的同时,该算法具有很好的实时性。     

Modeling MPEG Scalable Sources

Constant quality VBR video transmission causes a low utilization of network resources due to rare high-rate periods. Source scalability (i.e., the codec generates streams corresponding to several quality levels) is a promising approach to achieve a higher bandwidth utilization with a negligible reduction of the quality perceived by a human observer. To study bandwidth allocation for VBR scalable sources a characterization of the traffic generated by these sources is required. In this paper we develop and validate a Markovian model to characterize a scalable MPEG source. Our model is obtained by extending (without any additional state-space complexity) a Markov model previously developed for constant-quality MPEG sources. At any time instant, the model generates, with the same precision of the constant-quality model, the size of the highest quality pictures and approximates the size of the pictures corresponding to the other quality levels. By exploiting this model we show that the source scalability approach significantly increases the utilization while maintaining the quality of the video signal close to the highest quality for most of the time.     

在MPEG视频上的语义视频对象分割改进算法

随着MPEG－4,MPEG－7等标准的提出,如何提取语义视频对象已成为当前视频压缩和检索领域共同的研究课题。特别是MPEG－7对视频对象的形状检索提出了具体要求。针对顾创等人的WaterShed算法不能很好处理现有MPEG－1视频数据的缺陷,提出改进算法,从而能够在MPEG视频流中提取到具有光滑轮廓的语义视频对象,算法主要有以下两点改进：提出将类成员数作为分类算法的参数;有压缩域和解码后的图像上先后进行两次分割。实验结果表明,改进算法在鲁棒性和分割结果精度上比原算法有较大的改进,其分割结果可用于轮廓检索和重要视频对象检索。     

直接在MPEG压缩视频中获取颜色特征

虽然MPEG压缩视频提供的是压缩参数,但压缩参数也能反映视频序列中的颜色特征。文章通过分析MPEG压缩参数,提出了直接利用DC系数获取视频图像颜色特征的方法。     

基于决策树的MPEG视频镜头分割算法

压缩视频镜头的分割是视频内容分析中的一个难点,由于镜头在组织和索引视频中起关键性的作用,提出了一种基于决策树的MPEG视频镜头分割算法。该算法采用决策树这种机器学习方法对样本视频进行训练,通过融合运动信息、颜色、边缘等特征获得镜头分割的最佳阈值,较好地解决了压缩视频处理中检测镜头突变和渐变难题,同时还能够检测出镜头是否产生闪光现象和相机运动的产生。实验证明本算法在压缩视频镜头检测方面取得了较好的检测结果。     

ECC加密MPEG4视频的研究和实现

视频图像压缩编码是解决有限的存储空间与越来越丰富的视频信息之间矛盾的需要，同时也是满足节省通信信道带宽和视频实时传输的需要。视频图像信息的安全是为了防止敏感信息轻易地窃取、篡改、非法复制和传播。信息安全主要包括信息加密技术和信息隐藏两部分，本文主要研究视频信息加密技术。椭圆曲线加密系统（ECC）的安全性基于椭圆曲线离散对数问题的难解性。它是迄今为止每比特具有最高安全强度的密码系统。同其它非对称加密体制相比，椭圆曲线密码系统除了安全性高外，还具有计算负载小，密钥尺寸短．占用带宽少等优点，因此，椭圆曲线密码系统被认为是下一代最通用的公钥密码系统。我们采用椭圆曲线加密算法作为纯密码加密技术进行实验。发现纯密码加密技术有较好的效果。     

基于ZigZag置乱的MPEG4视频加密方案及改进

探讨了基于ZigZag置乱的MPEG4视频数据加密技术,指出了这种方案在安全性方面的不足,提出了改进方案。改进的方案中AC系数用不同的置乱表置乱,DC系数用高强度的加密算法AES加密。最后给出了改进后的加密效果,并且从加密速度,安全性和码流变化三个指标衡量了该方案的应用价值。     

基于频度域选择置乱算法的网络视频加密系统设计

从网络视频系统的实际需求出发,将频度域选择置乱MPEG加密算法与公钥基础设施PKI相结合,提出了包括视频流加解密及密码安全分发在内的一整套系统方案设计。该系统能满足处理大数据量视频信息的实时要求,切实保障了数据及系统安全性。     

ECC加密MPEG4视频的研究和实现

视频图像压缩编码是解决有限的存储空间与越来越丰富的视频信息之间矛盾的需要,同时也是满足节省通信信道带宽和视频实时传输的需要。视频图像信息的安全是为了防止敏感信息轻易地窃取、篡改、非法复制和传播。信息安全主要包括信息加密技术和信息隐藏两部分,本文主要研究视频信息加密技术。椭圆曲线加密系统(ECC)的安全性基于椭圆曲线离散对数问题的难解性。它是迄今为止每比特具有最高安全强度的密码系统。同其它非对称加密体制相比,椭圆曲线密码系统除了安全性高外,还具有计算负载小,密钥尺寸短,占用带宽少等优点,因此,椭圆曲线密码系统被认为是下一代最通用的公钥密码系统。我们采用椭圆曲线加密算法作为纯密码加密技术进行实验,发现纯密码加密技术有较好的效果。     

一种基于混沌加密算法的保密视频会议方案及实现

针对目前混沌加密算法重于理论研究的现实,结合P2P网络传输结构的安全隐患,以Windows Peer-to-Peer Networking平台的Graph模块为基础,设计了一种运用混沌加密算法进行通信数据加密的P2P保密视频会议方案。方案在P2P网络结构采用CA机制,在网络传输结构上层采用混沌加密算法以及动态密钥管理,构建视频会议的安全环境。在实现该方案基础上探索了混沌加密算法的可用性。     

A QoS-Enabled Transmission Scheme for MPEG Video Streaming

While MPEG is the de facto encoding standard for video services, online video streaming service is becoming popular over the open network such as the Internet. As the performance of open network is non-predictable and uncontrollable, the tuning of the quality of service (QoS) for on-line video streaming services is difficult. In order to provide better QoS for the delivery of videos, there are proposals of new encoding formats or new transmission protocols for on-line video streaming. However, these results are not compatible with popular video players or network protocols and hence these approaches are so far not very successful. We use another approach which tries to by-pass these problems. We designed a QoS Tuning Scheme and a QoS-Enabled Transmission Scheme for transmitting MPEG videos from video servers to clients. According to the traffic characteristics between the video server and each individual client, the QoS Tuning Scheme tunes the QoS to be delivered to each individual client on the fly. Furthermore, our QoS-Enabled Transmission Scheme can be applied over any protocol, such as HTTP which is the most popular protocol over the open network. With our transmission scheme, bandwidth can be better utilized by reducing transmitted frames which would have missed their deadlines and would eventually be discarded by the clients. This is achieved by sending frames according to their impact on the QoS in the playback under the allowed throughput. With these schemes, users can enjoy video streaming through their favorite video players and with the best possible QoS. In order to facilitate the real time QoS tuning, a metric, QoS-GFS, is developed. This QoS-GFS is extended from the QoS-Index, another metric which has taken human perspective in the measurement of video quality. Hence QoS-GFS is better than the common metrics which measures QoS by means of rate of transmission of bytes or MPEG frames. We designed and implemented a middleware to perform empirical tests of the proposed transmission scheme and QoS tuning scheme. Experiment results show that our schemes can effectively enhance the QoS for online MPEG video streaming services. The work reported in this paper was supported in part by the RGC Earmarked Research Grant under RGC HKBU 2074/01E, and by the FRG under FRG 00-01/I. Joseph Kee-Yin Ng received a B.Sc. in Mathematics and Computer Science, a M.Sc. in Computer Science, and a Ph.D. in Computer Science from the University of Illinois at Urbana-Champaign in the years 1986, 1988, and 1993, respectively. Dr. Ng is currently an associate professor in the Department of Computer Science at Hong Kong Baptist University. His current research interests includes Real-Time Networks, Multimedia Communications, Ubiquitous/Pervasive Computing, Mobile and Location-aware Computing, Performance Evaluation, Parallel and Distributed Computing. Dr. Ng is the Technical Program Chair for TENCON 2006, General Chair for The 11th International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA 2005), Program Vice Chair for The 11th International Conference on Parallel and Distributed Systems (ICPADS 2005), Program Area-Chair for The 18th & 19th International Conference on Advanced Information Networking and Applications (AINA 2004 & AINA 2005) and he had served as the General Co-Chair for The International Computer Congress 1999 & 2001 (ICC'99 & ICC'01), the Program Co-Chair for The Sixth International Conference on Real-Time Computing Systems and Applications (RTCSA'99) and the General Co-Chair for The 1999 and 2001 International Computer Science Conference (ICSC'99 & ICSC'01). Dr. Ng is a member of the Editorial Board of Journal of Pervasive Computing and Communications, Associate Editor of Real-Time Systems Journal and Journal of Mobile Multimedia. He is a guest editor of International Journal of Wireless and Mobile Computing for a special issue on Applications, Services, and Infrastructures for Wireless and Mobile Computing. Dr. Ng is currently the Region 10 Coordinator for the Chapter Activities Board of the IEEE Computer Society, and is the Coordinator of the IEEE Computer Society Distinguished Visitors Program (Asia/Pacific). He is a senior member of the IEEE and has been a member of the IEEE Computer Society since 1991. Dr. Ng has been an exco-member (1993–95), General Secretary (1995–1997), Vice-Chair (1997–1999), Chair (1999–2001) and is the immediate past Chairman of the IEEE, Hong Kong Section, Computer Chapter. Dr. Ng received the Certificate of Appreciation for Leadership and Service (2000–2001) from IEEE Region 10 and the IEEE Meritorious Service Award from IEEE Computer Society at 2004. He is also a member of the IEEE Communication Society, and ACM. Karl R.P.H. Leung received his Ph.D. from The University of Hong Kong. He is currently a Principal Lecturer in the Department of Information and Communications Technology at the Hong Kong Institute of Vocational Education (IVE). He is the founder of the Compuware Software Testing Laboratory in the IVE with a donation from the Compuware Asia Pacific Co. Ltd. His research areas include: domain modeling, mission critical software engineering methodology, secure workflow systems, GSM-based location estimation, and QoS of MPEG streaming. He is a Senior Member of the IEEE and IEEE Computer Society, and has held major office of the IEEE Hong Kong Section Computer Chapter. While he was the chairman in 1998, the Chapter won the IEEE Most Outstanding Computer Society Chapter Award. He is also a Chartered Engineer of Engineering Council (UK), a Chartered Information Systems Engineer of British Computer Society (UK), an Engineer of Hong Kong Institution of Engineers, Registered Professional Engineer (Information) of Hong Kong Engineers Registration Board, and a member of ACM, BCS, ACS, HKIE and HKCS. Calvin Kin Cheung Hui received a B.Sc. (First Class Honours) in Computer Science, and a M.Phil. degree in Computer Science from Hong Kong Baptist University in the years 1999, and 2002, respectively. Mr. Hui's research interests includes Real-Time Networks, VoD Systems, Video Streaming, Multimedia Communication, and Distributed Systems Performance Evaluation.     

Internet访问的实时管理

讨论了在开放计算机实验室中对用户访问Ｉｎｔｅｒｎｅｔ实时管理问题,介绍了对 问权限实时管理及访问费用实时结算的一种实现方法。     

基于DirectShow设计视频加密Transform Filter

实现了基于DirectShow技术开发视频加密TransformFilter。首先介绍了视频加密的原理和方案,分析了Di-rectShow的体系结构,然后研究了基于DirectShow技术如何实现视频加密TransformFilter,并给出了试验结果和结论。试验结果表明该Filter可以对实时视频进行加密,加密速度快,效果好。     

基于混沌的视频流选择加密算法

基于网络的多媒体流的安全加密技术正成为人们研究的热点,目前的算法在安全性和实时性上都各自存在缺点,文章通过针对压缩流的具体特性,采用混沌伪随机序列发生方法,将非对称公钥加密算法和流加密算法相结合,提出了基于混沌的选择性视频流加密算法．通过密码分析、算法评估和具体试验效果分析,该算法具有较好的实时性、安全性和易实施性。