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多媒体同步中QoS到QoP的模糊映射 总被引:3,自引:0,他引:3
针对多媒体实时传输的质量要求,提出了同步QoP映射器的思想,即通过建立QoS(quality of service)到QoP(quality of presentation)的模糊映射,从感知的角度为分布式多媒体提供同步质量的度量工具.从分析Ralf Steinmetz博士的感知实验出发,提出了构造同步QoP映射器的算法.此算法以拟合感知困惑曲线为基础,通过提取模糊隶属度函数来实现QoS到QoP的模糊映射.在此基础上,给出了将此模糊QoP映射器应用于实时媒体传输的同步时间模型的实例,实例以模糊QoP映射器的模糊隶属度函数作为模糊控制机制的条件来控制同步语义的变迁,以实现媒体同步质量的调整. 相似文献
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内容适配技术是实现通用多媒体访问的主流技术,如何实现内容适配系统是内容适配技术研究中的重要问题。基于SOA架构设计并实现内容适配系统。系统具有数据管理、服务管理、内容适配和内容服务功能。采用客观和主观指标结合的评价体系,对内容适配系统的服务质量进行评价。 相似文献
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自适应服务质量技术能有效地适应随时间变化的网络环境.提出了基于服务质量水平max-mi n公平的带宽分层自适应模型.此模型建立在应用层和网络层自适应控制的机制上.网络层利 用资源探测协议来实现基于服务质量水平max-min公平的带宽分配,而应用层实现特定于应 用的自适应服务. 相似文献
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视频点播服务器的服务质量控制框架 总被引:2,自引:0,他引:2
视频点播服务器工作于开放的网络环境中,系统负载难以预测,其运行时资源瓶颈依赖于实时服务类型.基于性能模型和实时负荷估计方法,本文提出视频点播服务器的服务质量控制框架,提供系统负荷监控、准入控制和区分服务等三种服务质量控制.实际系统的验证实验表明,本文的方法可以有效的对系统负荷进行监控,确保系统负荷稳定在服务提供商希望的水平线以下,向不同级别的用户提供不同质量级别的服务. 相似文献
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Solange Rito Lima Paulo Carvalho Vasco Freitas 《Journal of Network and Systems Management》2004,12(3):397-426
This article proposes a distributed admission control (AC) model based on on-line monitoring to manage the quality of Internet services and Service Level Specifications (SLSs) in class-based networks. The AC strategy covers intra- and interdomain operation, without adding significant complexity to the network control plane and involving only edge nodes. While ingress nodes perform implicit or explicit AC resorting to service-oriented rules for SLS and QoS parameters control, egress nodes collect service metrics providing them as inputs for AC. The end-to-end operation is viewed as a cumulative and repetitive process of AC and available service computation. We discuss crucial key points of the model implementation and evaluate its two main components: the monitoring process and the AC criteria. The results show that, using proper AC rules and safety margins, service commitments can be efficiently satisfied, and the simplicity and flexibility of the model can be explored to manage successfully QoS requirements of multiple Internet services. 相似文献
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Advances in multimedia computing technologies offer new approaches to the support of computer-assisted education and training within many application domains. Novel interactive presentation tools can be built to enhance traditional teaching methods with more active learning. Since a variety of user expectations are possible in such an environment, research must address the incorporation of these factors into presentation tools. During an interactive learning/training process, presentation tools must be able to handle various types of delays. A flexibly adjustable quality of service (QoS) should thus be supported. In this paper, we investigate a framework and systematic strategies for supporting the continuous and synchronized retrieval and presentation of multimedia data streams in a client/server distributed multimedia environment for educational digital libraries. Specifically, we establish a practical framework for specifying multimedia objects, tasks, schedules, and synchronization constraints between media streams. We identify the QoS parameters critical to the support of multimedia presentations for learning and training activities. Based on the proposed framework and QoS specifications, we develop presentation scheduling and buffer management strategies which can enforce the specified QoS requirements in an educational digital library environment. 相似文献
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在设计一个分布式多媒体系统时,具有挑战性的问题之一是如何在系统的不同层次为各模式设计合适的规格描述模型,并提供不同模型的变换方法的集成与同步策略,在本文中,我们给出了几种多媒体对象的表示模型和变换算法,它们把高层的多媒体对象变换成可以用来支持多媒体对象展示和通信的实用模式,在该模式中能较好地保持多媒体对象的集成与同步特性。 相似文献
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一种目的节点启动多媒体组通信成员加入算法 总被引:1,自引:0,他引:1
文中在基于服务质量的动态组多媒体通信初始路由建立算法基础之上,提出了一种由目的节点启动的基于服务质量的支持成员加入动态组的算法。该算法同初始路由建立算法及目的节点退出算法相结合,可以提供对分布式多媒体动态组应用服务质量保证的支持。 相似文献
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徐练 《计算机工程与应用》2005,41(19):158-161
该文提出的应用层多播QoS自适应方法建立在由多个单播HPF路径构成的多播树基础上,多播组成员节点在一个HPF会话中是接收者,而可能在其它一些HPF会话中作为转发器。多播树由最大瓶颈带宽生成树算法生成,媒体流的传输协议采用HPF,由最大瓶颈带宽生成树上的分支节点作转发器来实现速率自适应和包丢弃算法,以达到整个多播组的平均带宽利用最大化。 相似文献
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为了充分体现服务质量(QoS)的不确定性和用户偏好的模糊性,本文将模糊集理论引入基于QoS的Web服务组合中,将不适合精确表示的QoS属性和用户偏好等信息用三角模糊数表示.然后基于权重和法计算模糊总目标,通过设计新的模糊数比较方法,改写Pareto支配关系,将基于模糊数比较的单目标优化问题转化为多目标优化问题,并设计模糊多目标遗传算法(FMOGA)求得Pareto最优解集.该方法不仅能够得到更加贴近实际情况的优化解,同时也解决了多属性决策方法无法对大量候选服务进行全局优化的问题.最后通过实验验证了该算法的有效性和优越性. 相似文献
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Roberto Canonico Maurizio D'Arienzo Simon Pietro Romano Giorgio Ventre 《Software》2003,33(10):901-911
A number of distributed applications require communication services with quality of service (QoS) guarantees. Building global‐scale distributed systems with predictable properties is one of the great challenges for computer systems engineering in the new century. Work undertaken within the Internet Engineering Task Force has led to the definition of novel architectural models for the Internet with QoS support. According to these models, the network has to be appropriately configured in order to provide applications with the required performance guarantees. In next‐generation networks, enabling applications to interact with the underlying QoS services is of primary importance. Hence, several special‐purpose application programming interfaces (APIs) have been defined to let applications negotiate QoS parameters across QoS‐capable networks. However, so far, none of these APIs are available in different operating environments. We believe that such features should be embedded in programming environments for distributed applications. In this work we present how we included QoS control features in Tcl, a programming language that has been widely adopted for the development of distributed multimedia applications. Our work has led to the implementation of QTcl, an extended Tcl interpreter that provides programmers with a new set of primitives, in full compliance with the standard SCRAPI programming interface for the RSVP protocol. QTcl in highly portable, in that it enables standard QoS negotiation to be performed in a seamless fashion on the most common operating systems. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Boutaba Raouf Ren Ned Ning Rasheed Yasser Leon-Garcia Alberto 《Multimedia Tools and Applications》2002,16(1-2):99-136
In this paper, we apply a top-down approach to describe the architecture components of Distributed video production (DVP) systems. We first introduce the concept of a Distributed video production environment and describe typical DVP tasks involved. We then propose a generic layered functional model that captures the characteristics of the DVP architecture. Subsequently, we identify system and network performance parameters and discuss possible network protocol stack realizations for the transport of DVP traffic. Finally, we propose a quality of service-sensitive model for resource allocation and optimization. 相似文献
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延迟敏感的移动多媒体会议端到端服务质量保障 总被引:1,自引:0,他引:1
随着异构无线网与智能移动终端的快速发展,移动多媒体会议逐渐成为重要的网络应用.然而,在不可靠、多变的无线网络环境下,因传输单向延迟过长所造成的多媒体视频丢帧、跳帧、断续等现象严重影响会议的服务质量和用户体验.文中提出一种应用层端到端服务质量保障方法.该方法将数据包分段重组与异构无线网路径分集传输相结合,在考虑带宽、延迟、权重以及长度等多种参数情况下对视频数据包分段并发送,各分段经路径分集传输到达客户端、通过有效性检验后进行重组.文中为实现该方法,设计了一种服务器-客户端形式多路径数据包调度算法,构建端到端虚通路保障视频流的快速传输.实验数据表明,此方法能够有效地整合异构无线网带宽,减少传输单向延迟. 相似文献