A proxy architecture for collaborative media streaming

Streaming media from the Internet is a successful application for end-users. With the upcoming success of mobile devices and home networking environments, cooperation among users will become more important in the future. To achieve such cooperation, explicit middleware standards have been defined. On the other hand, Internet conferencing applications do not handle collaborative streaming sessions with individual control for each user. We propose a new concept for cooperation exemplary for collaborative media streaming using IETF multimedia session control protocols together with a proxy architecture. This concept enables both synchronization among clients and flexible control to individual users.     

Analysis of a CDN–P2P hybrid architecture for cost-effective streaming media distribution

To distribute video and audio data in real-time streaming mode, two different technologies – Content Distribution Network (CDN) and Peer-to-Peer (P2P) – have been proposed. However, both technologies have their own limitations: CDN servers are expensive to deploy and maintain, and consequently incur a cost for media providers and/or clients for server capacity reservation. On the other hand, a P2P-based architecture requires sufficient number of seed supplying peers to jumpstart the distribution process. Compared with a CDN server, a peer usually offers much lower out-bound streaming rate and hence multiple peers must jointly stream a media data to a requesting peer. Furthermore, it is not clear how to determine how much a peer should contribute back to the system after receiving the media data, in order to sustain the overall media distribution capacity.In this paper, we propose and analyze a novel hybrid architecture that integrates both CDN- and P2P-based streaming media distribution. The architecture is highly cost-effective: it significantly lowers the cost of CDN capacity reservation, without compromising the media quality delivered. In particular, we propose and compare different limited contribution policies for peers that request a media data, so that the streaming capacity of each peer can be exploited on a fair and limited basis. We present: (1) in-depth analysis of the proposed architecture under different contribution policies, and (2) extensive simulation results which validate the analysis. Our analytical and simulation results form a rigorous basis for the planning and dimensioning of the hybrid architecture.     

An efficient scheduling algorithm for scalable video streaming over P2P networks

During recent years, the Internet has witnessed rapid advancement in peer-to-peer (P2P) media streaming. In these applications, an important issue has been the block scheduling problem, which deals with how each node requests the media data blocks from its neighbors. In most streaming systems, peers are likely to have heterogeneous upload/download bandwidths, leading to the fact that different peers probably perceive different streaming quality. Layered (or scalable) streaming in P2P networks has recently been proposed to address the heterogeneity of the network environment. In this paper, we propose a novel block scheduling scheme that is aimed to address the P2P layered video streaming. We define a soft priority function for each block to be requested by a node in accordance with the block’s significance for video playback. The priority function is unique in that it strikes good balance between different factors, which makes the priority of a block well represent the relative importance of the block over a wide variation of block size between different layers. The block scheduling problem is then transformed to an optimization problem that maximizes the priority sum of the delivered video blocks. We develop both centralized and distributed scheduling algorithms for the problem. Simulation of two popular scalability types has been conducted to evaluate the performance of the algorithms. The simulation results show that the proposed algorithm is effective in terms of bandwidth utilization and video quality.     

Enhancing P2P overlay network architecture for live multimedia streaming

The number of live multimedia streaming applications is increasing, explaining the use of many overlay network topologies. Application-layer multicast (ALM) that it is a feasible alternative to multimedia stream has attracted considerable attention. However, a serious problem of ALM is that the multicast tree may be fragile, and peer failure causes tree partitions. This work presents a novel Hierarchical Ring Tree (HRT) architecture for Peer-to-Peer (P2P) live multimedia streaming. The proposed architecture combines ring-based and tree-based structures in a robust, scalable, reliable and resilient structure that can be used practically as an ALM topology. When peers enter or leave the system, the topology can be recovered rapidly such that live multimedia stream can be delivered smoothly with a low latency. The proposed HRT topology is maintained efficiently without splitting or merging trees. The performance of the proposed architecture and algorithms is evaluated experimentally. Experimental results indicate that the proposed topology can be used in a high-churn P2P network with a small delay. Simulation and experiment results reveal that the proposed architecture has a lower overhead than the ZIGZAG approach when handling peers’ joining or leaving, exhibits faster recovery, better quality-of-service during streaming, and a more robust topology, even with an extremely high number of peers joining/leaving.     

一种P2P流媒体系统中的缓存替换算法

针对视频节目受欢迎程度不同的特性,提出一种P2P流媒体系统中的缓存替换算法,通过将系统中的全部视频片段分类,为其赋予不同的优先级,并周期性地更新该值,同时考虑视频片段被访问次数和最近被访问的情况,使得被替换出存储空间的片段更加合理。实验表明,该算法能提高缓存命中率及系统的启动延时,性能较优。     

On index load balancing in scalable P2P media distribution

Peer-Peer (P2P) technologies have recently been in the limelight for their disruptive power in particular they have emerged as a powerful multimedia content distribution mechanism. However, the widespread deployment of P2P networks are hindered by several issues, especially the ones that influence end-user satisfaction, including reliability. In this paper, we propose a solution for an efficient and user-oriented keyword lookup service on P2P networks. The proposed mechanism has been designed to achieve reliability via index load balancing and address the scalability issues of extremely popular keywords in the index. The system performance have been analytically derived as well implemented using the OpenDHT framework on PlanetLab.

P2P流媒体系统模型及关键技术研究

介绍了典型的P2P流媒体系统模型,并指出基于多播树协议的服务模型与基于Gossip协议的服务模型的区别.分析了对P2P流媒体系统的节点的调度算法、数据存储、资源发现、内容分发等关键技术,在此基础上指出了P2P流媒体系统进一步的研究方向.     

P2P视频直播数据调度算法

P2P技术解决了传统流媒体应用中的不能支持大用户的问题.而数据调度算法一直是P2P研究中的热点问题.在给出了P2P视频直播系统中节点能力的定义和计算方法后,结合BT中的Rarest First策略,提出了一种基于节点能力的适用于P2P视频直播系统的数据调度算法.该算法既考虑了流媒体数据具有时间限制的特性,同时也考虑了如何能充分的利用节点的上传带宽,增进了系统的负载平衡.     

Adaptive,incentive and scalable dynamic tree overlay for P2P live video streaming

In this paper, we propose a new multicast tree framework to be used in peer-to-peer (P2P) live video streaming systems. The proposed system, adapts the tree links under high peer churn and runs in a totally distributed manner. In order to provide this dynamism and seamless streaming at the same time, we propose a cross layer design involving scalable video codec, backup parents and hierarchical clusters. The performance of the system is measured in real world environment PlanetLab that has nodes distributed all over the world. The experiments show that the proposed system provides high quality of experience (QoE) in terms of Peak Signal to Noise Ratio (PSNR), playback delay and duration of pauses. The proposed system also provides incentive mechanism to its users.     

核心路由器的流媒体业务支持策略

流媒体在互联网应用中占有越来越重要的地位,要实现核心网对各种流媒体业务的有效支持,必须在核心节点处解决流媒体业务对延时、带宽、QoS等方面的性能要求.从流媒体的业务识别、流保序、QoS保证、组播复制几个方面,探讨了核心路由器的流媒体支持方案.     

一种基于激励机制的P2P流媒体数据调度模型

针对P2P流媒体中现有算法在数据调度时不够公平的问题,提出了一种新的具有激励作用的算法模型.该算法模型可以根据节点的丢包率、贡献效率动态调节节点带宽分配以达到接收节点利益理性最大化和系统整体公平,提高了系统传输效率.仿真实验表明,该算法模型促进了节点的参与传输调度,达到了维持系统公平的目的.     

基于多源的P2P流媒体传输系统的设计

针对实际P2P网络中存在的异构性问题,提出一种基于多源的P2P流媒体传输系统。     

P2P流媒体播放系统中插播广告的实现技术

为了满足P2P流媒体播放系统中插播广告需求,结合P2P网络的特点,提出了消耗系统内存少的无缝插播广告技术.该技术采用基于资源相关性的流媒体主动预取算法获取广告资源,应用动态共享内存池技术来存储和播放广告.该插播广告技术的应用拓展了广告发布的领域,提高了广告的影响力,增加了广告商的客户量,使P2P流媒体运营商具有更强的竞争力.     

基于时间间隔的P2P流媒体直播系统缓存算法

针对基于分片传输机制的P2P流媒体直播系统客户端缓存问题,为提高节点间请求数据分片的命中率和避免数据分片大量冗余,提出一种依赖邻居节点请求量的节点缓存替换算法.该算法将分片在节点的缓存时间进行等间隔划分,利用马尔可夫链转移概率矩阵计算理论,预测分片在下一时刻的缓存价值.并将该算法和传统算法FIFO及LRU算法进行了对比实验,实验结果表明,在同等条件下,该算法相较于传统算法能更好地提高数据的命中率.     

基于P2PSIP的移动实时流媒体系统的安全架构

在分析移动实时流媒体应用对P2P环境提出的安全性方面挑战的基础上,提出了基于P2PSIP的移动实时流媒体系统MPSLSS的安全架构.针对MPSLSS系统的可管控性设计了一种分层混合式P2P网络架构,并采用STRIDE模型举例分析了MPSLSS系统面临的安全威胁,在此基础上提出了一种适用于移动实时流媒体应用的系统安全架构,并对其进行了分析.     

基于P2P的流媒体教学系统结构研究

随着计算机网络技术和数字技术的迅速发展,网络教育已经进入了数字化、智能化、个性化的发展阶段。本文致力于研究网络学习系统中的基于P2P流媒体技术的视频教学资源系统平台的构架,为学习者提供一个＂以学习者为中心＂的网络化学习环境。     

基于P2P覆盖树网络的流媒体传输技术优化研究

PeerCast是一个基于P2P网络的流媒体传输系统,各节点被组织成树状来进行数据的分发.但没有一个有效的机制来维护树的平衡和保证所选取的父节点是最佳的节点.在此基础上,对该系统进行优化,在媒体数据包上加一个字节用来标识当前节点与根节点的距离,并对节点间响应消息进行优化.实验结果表明,这些优化措施能够有效的维护树的平衡和降底数据传输时延.     

P2P网络移动流媒体转码方法研究

为解决移动设备异构性影响视频流媒体应用的问题,提出了一种P2P网络移动流媒体的交错分布转码方法.该方法允许多个固定节点为一个移动设备转码,生成多个交错子流给目标移动节点,子流在移动节点上组装,降低了转码对固定节点计算能力的需求.分析了节点失效对分布转码造成的影响,交错子流可以减弱这种影响,强化数据包丢失错误恢复机制.比较了该方法与多描述编码之间的性能差异,实验结果表明,应用该方法移动流媒体在节点失效和不良无线信道条件下鲁棒性好.     

面向P2P流媒体基于Mesh优先的应用层组播算法

P2P流媒体在网络上已经得到了广泛的开发与应用。一个流媒体系统中的应用层组播树的构建算法将直接影响到整个系统的效率及质量。提出一种新的服务于分布式覆盖网框架的应用层组播树的构建算法——CDDMA。CDDMA首先自治地构建一个探测节点结合,利用PPAF启发式综合考虑传输时延与节点出度作为加入节点加入组播树的评价函数,解决了原有的基于Mesh优先的应用层组播协议考虑网络因素单一的问题,并能解决组播树负载不均衡的问题。在SMesh的基础上,给出了CDDMA的实现,通过类似Internet网络拓扑结构的仿真,表明了这种算法降低了链路压力及路径伸展率。