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基于帧拆分的MPEG视频的可靠传输 总被引:3,自引:0,他引:3
1.前言近年来在Internet上传送MPEG视频的需求和应用越来越多。多媒体交互式应用要求短时延,一般采用UDP协议进行传送,但UDP是不可靠传输协议,传送过程中的包丢失将导致视频质量下降。MPEG使用的帧间预测技术使得一旦I-帧或P-帧在传送中丢失,依赖它们的许多帧将受影响,即使很小的包丢失率也会严重影响接受到的MPEG视频的质量。 相似文献
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介绍了一种对MPEG VIDEO码流中场景切换点进行高速检出的新方法,在计算各帧相对于预测帧的类似度之后进行了类似度的归一化,降低了cut检出算法的复杂度,提高了检出的速度。 相似文献
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MPEG—2可分级图像编码的实时传输的实现 总被引:4,自引:0,他引:4
本文介绍了基于MPEG-2国际标准的可分级编码方法,并以数据分割可分级方法对一个视频源产生的具有不同视频质量的视频层,用基本层编码提供基本视频质量,增强层则被编码来增强基本层。实验结果证明,增强层对基层的图像质量确实有相当的增强作用,并能自动适应网络信道的状况满足实时视频传输的要求。 相似文献
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面向TCP友好的音视频自适应实时传输 总被引:1,自引:0,他引:1
该文在RTP协议之上提出了一种多媒体自适应实时传输的方案—TCP友好的自适应实时传输。它具有带宽——动态自适应和TCP友好的特点,它不仅能根据网络实际情况,快速、平滑地调整音视频的传输速率,而且能够使基于UDP传输的音视频不至于过度抢占基于TCP的数据流带宽。为了实现该方案,该文在对RTP中的AIMD算法进行深入分析的基础上,对其中的递增步长和乘性因子两个参数进行了修改,不仅使这两个参数是可变的,而且根据TCP分析模型将两个参数设置为TCP某个指标来达到TCP友好。 相似文献
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随着网络的应用,视频的在线传输和播放也应用越来越广。在网络带宽不足的情况下,视频文件尽量小是我们追求的目标。本文介绍了MPEG压缩算法如何实现对视频的压缩,并介绍MPEG视频压缩中具体压缩算法的应用。并对MPEG的几种标准进行比较和介绍。 相似文献
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MPEG流封装成RTP协议包的具体实现 总被引:2,自引:0,他引:2
MPEG流是由多个层次构成手复杂的媒体流,实时传输协议(RTP)是针对多媒体数据进行实时传输的协议。MPEG流依据RTP以流媒体的形式进行实时传输是目前MPEG视音频传输的一个有效的方法。本文给出了将MPEG流封装成RTP协议包的具体实现。 相似文献
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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. 相似文献
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镜头分割算法是实现视频检索的关键,本文提出一种针对MPEG视频流的快速分割镜头的算法,介绍了该算法的基本原理与实现过程。该算法利用压缩视频中的可用信息,通过计算帧的内编码宏块数量的比例作为是否需要进行镜头分割判别的标识,进而计算MPEG视频流B帧各宏块编码类型来检测发生镜头分割的帧住置,并进行了相关的实验。实验
结果表明,该算法能快速有效地检测镜头分割,且计算量较小。 相似文献
结果表明,该算法能快速有效地检测镜头分割,且计算量较小。 相似文献
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变比特率视频业务是将来多媒体业务的主要组成部分,为保证高质量,实时传输的需要,准确把握视频特征,结合网络传输机制为多媒体通信提供更好的服务质量(QoS)是目前亟待解决的问题之一,该文针对面向RCBR(Renegotiated Constant Bit Rate)网络的变比特率MPEG视频提出了基于编码结构的自适应预测算法,它充分利用了视频流的周期相关性,能准确快速,无延迟地对视频帧的码率进行预测,通过网络动态地为视频分配合适的带宽,不仅能达到高质量,低延迟抖动的视频服务,并且提高了网络的利用率,与分配固定带宽的网络相比,其网络缓冲的排除性能和网络的利用率有明显提高。 相似文献
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流媒体实时传输技术是当前通信领域研究的热点之一,流媒体的最大特点是它的实时性,即一边传输一边播放。MPEG是Motion Picture Experts Group的缩写,它是国际通用的多媒体压缩编码标准。RTP协议是IETF提出的适合实时数据传输的协议,它有效的弥补了现有的传输协议对实时性应用支持的不足,讨论如何使用RTP协议对MPEG流打包封装,并在接收端对丢包进行错误恢复和再同步。 相似文献