共查询到19条相似文献,搜索用时 109 毫秒
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随着视频流点播应用在Internet上的流行,服务器和骨干网络的带宽越来越成为了视频流点播发展的主要制约因素.为此,根据视频点播的特点和代理服务器除了能在服务器与客户端之间进行通信中继以外,还可缓存部分视频内容以直接满足客户请求的事实,提出了一个基于均匀分段的代理缓存管理策略以缓解视频流点播系统对服务器及骨干网络带宽的需求,并详细介绍了代理缓存管理策略的具体操作.理论分析表明文章提出的代理缓存管理策略能大大的减少系统对骨干网络带宽的需求,并能为客户端提供理论零延时服务.实验结果证明所提缓存管理策略明显优于现有的基于完全缓存或前缀缓存的代理缓存策略. 相似文献
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针对无线局域网,提出了一种基于RTP/RTCP协议下MPEG-4标准的多路实时视频流的具体实现方案,提出了一种有效的基于时间戳的多路视频同步模型。针对无线QoS机制,系统应用了一种基于RTCP反馈友好码率控制算法TFRC的ECN算法,根据ECN标记包率来动态调整发送码率实现拥塞控制。实验表明该传输方案能获得较好的视频传输质量。 相似文献
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无线网络视频传输是当前网络研究的热点方向,真实视频流是进行网络协议性能评价的最佳业务,然而当前主流网络仿真软件都不支持真实视频流业务。在网络仿真软件Qualnet中设计实现了无线网络视频传输评测系统VtPet。该系统将视频编解码器集成到Qualnet中,支持真实视频流的实时编码、传输、解码以及播放。收集统计多种视频传输性能参数,除了常用的网络性能参数(如吞吐率、延迟等)外,还有能反映接收端视频主、客观质量的性能参数及手段。VtPet简单易用,性能参数评价全面,是进行无线网络视频传输评测的有效工具。Abstract: Video transmission in wireless network attracts many attentions nowadays.It’s important to evaluate the performance of network protocols via real video stream.However,none of the well-known network simulation software supports real video stream traffic,including Qualnet.VtPet (Video transmission Performance evaluation toolkit) is developed in Qualnet.VtPet integrates video codec into Qualnet,so that it can support real video stream traffic.Extensive performance metrics are collected,such as end-to-end throughput,delay,as well as PSNR.VtPet is easy to use with clean interface.It can facilitate to evaluate performance of video transmission in wireless network efficiently. 相似文献
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事件检测是视频语义分析中的一大难题。在视频中有多种语义丰富的模态信息,融合多模态信息可以帮助准确的检索出所需的事件。提出了一种基于HMM有效融合多模态对象的足球视频语义分析方法。首先从视频中抽取音频流,然后基于CHMM将音频分类。接着根据时间对应关系将音频对象与视频流融合,然后在相应的视频流镜头中基于DHMM融合多种模态对象实现精彩事件如射门、犯规及一般事件的检测,对射门事件进一步结合比分字幕的出现检测进球事件。另外,对DHMM模型的结构、参数初始值尤其是参数约束条件进行了详细地描述。实验证实提出的算法具有较好的效率。 相似文献
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提出一种在接收端实现的媒体同步控制算法。算法分别根据音频和视频播放缓冲区的占用水平,在不影响音频播放质量的情况下调整音频帧的长度,实现音频流媒体内同步;通过改变视频流的播放帧率达到视频流媒体内同步。并以音频流为主媒体流,视频流为从媒体流,比较最近播放的音频帧和视频帧的播放时间标签,调整视频帧的播放持续时间来取得音视频媒体间同步。实验结果表明,在不增加播放时延的情况下,该算法可以实现单个媒体流的媒体内同步,并达到音视频媒体间同步。 相似文献
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With the rapid development of Internet, mobile networks and high-performance networking technology,multiple constrained QoS multicast routing optimization in networks with uncertain parameters has become a very important research issue in the areas of networks and distributed systems. It is also a challenging and hard problem to the next generation Internet and high-performance networks, and has attracted the interests of many people. This paper discusses the multiple constrained QoS multicast routing problem, which may deal with the delay, delay jitter,bandwidth and packet loss metrics, and describes a network model for researching the routing problem. The paper mainly presents multiple constrained QoS multicast routing algorithm (MCQMRA), a QoS multicast routing policy for Internet,mobile network or other high-performance networks, which is based on the genetic algorithm (GA) and can provide QoS-sensitive paths in a scalable and flexible wayin the network environment with uncertain parameters. The MCQMRA can also optimize the network resources such as bandwidth, delay, packet loss metrics and can converge to the optimal or near-optimal solution within few iterations, even for the network environment with uncertain parameters. Simulation results show that MCQMRA is an available approach to QoS multicast routing decision. 相似文献
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QoS multicast routing algorithm based on GA 总被引:9,自引:2,他引:9
1 .INTRODUCTIONTheprovisionofquality of service (QoS) guaranteesisofutmostimportanceforthedevelopmentofthemulticastservices .Multicastroutinghascontinuedtobeaveryimportantresearchissueintheareasofnet worksanddistributedsystems.Ithasattractedtheinterestsof… 相似文献
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Zhang Fang Xiao Song & Wu Chengke ISN National Key Lab Xidian University Xi''''an P. R. China 《系统工程与电子技术(英文版)》2005,16(1)
1.INTRODUCTION WiththeadventofInternetrevolutionandavailability ofgrowingnetworkresources,streamingvideoisbe comingincreasinglypopularamongInternetmultime diaapplications.Inordertomaintaingoodqualityof service(QoS)inthecurrentbest effortInternet, bandwidthadaptationanderrorresiliencetothevary ingnetworkconditionsaredesiredforstreamingvideo overtheInternet.Onegoodsolutiontotheseprob lemsistocompressandtransmitavideosequence withscalabilityandAUPLP.Fromthepointofview videocoding,sca… 相似文献
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Xie Xiaohui Sun Lining Du Zhijiang & Cai HegaoRobotic Research Institute Harbin Institute of Technology Harbin P.R.China 《系统工程与电子技术(英文版)》2005,16(2)
1.INTRODUCTION Teleoperationmakeshumansensetoremotesiteand byitmanyapplicationcanbeappliedintoreality.A longdistanceteleoperationmayhavemuchmore meaningtopeople.Throughspace,sea,andnet work,teleoperationshowsitscharm.Whenrobotis inducedinteleoperationastheexecutoritisnamedas telerobotics.NowInternetisprevalentintheworld,overitconstructingateleroboticshasmuchmoread vantagethanothers,likeconstructingeasily,cheap costandmaintenanceconvenientlyetc.Butthereare alsosomedrawbacksinit,liketimede… 相似文献
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传感器网络技术的发展对网络服务质量提出了要求,如何在满足一定的服务质量要求前提下实现能量的优化是传感器网络设计必须面对的问题。现有的相关研究主要集中在如何从路由层和链路层来保证一定的QoS指标,本工作将传感器网络中的QoS支持延伸到拓扑管理层,提出了一种支持一定QoS要求的高效的拓扑控制算法,该算法构造一种具有梯度分布特征的节点拓扑结构以平衡网络数据流在sink节点处的聚集。NS2仿真证明了该结构对QoS支持的可行性。仿真表明,该算法以较少的冗余节点增加可将延时和丢包率分别降低50%和40%,证明了该机制在高速率数据场景下的高效性。还通过NS仿真分析了算法实现中关键参数的选取原则。 相似文献
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提出基于多波束天线静止地球轨道卫星的宽带移动通信系统方案,与常规结构同类系统用户相比,其容量更大、业务质量更好。采用时隙同步码分多址辅助的多频时分多址接入、程控交换与因特网协议交换结合的交换、时分复用和准正交时分复用下行链路传输体制,可显著增加用户量,简化星上设备,改善互联网应用业务质量。用户接入信道数为173 880, 最高用户下载速率达155 Mbps。仿真结果表明,140个波束、每波束26个16幅度相移键控信号的用户下行链路传输比频分复用传输的链路性能改善11.65dB,使得宽带用户“动中通”天线等效口径缩小至原来的1/4,成本大幅降低。 相似文献
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Cui Xunxue Gao Wei & Fang Hongyu. New Star Research Institute of Applied Technology Hefei P. R. China . Jiangsu Key Laboratory of Computer Information Processing Technology Soochow University Suzhou P. R. China . Department of Electronic Engineering Information Science University of Science Technology of China Hefei P. R. China . School of Electronic Science Technology Anhui University Hefei P. R. China 《系统工程与电子技术(英文版)》2005,16(2)
1.INTRODUCTION Qualityofservice(QoS)multicastroutinghascon tinuedtobeaveryimportantresearchtopicintheIn ternet.Multicastisacommunicationservicethatal lowssimultaneoustransmissionofthesamemessage fromonesourcetoagroupofdestinationnodes.To carryoutdifferentmulticastsessions,anetworkmust minimizethesessions’resourceconsumption,while meetingtheirrequirements.Efficientallocationof networkresourcestosatisfyQoSrequirementsisthe primarygoalofmulticastrouting.Howevertheinter dependencyandconfli… 相似文献