流媒体技术在电视监控系统中的应用

分析了现有煤矿中采用的电视监控系统所存在的问题和不足，提出并设计了基于流媒体技术的新型电视监控系统的应用方案。     

大规模流媒体多播系统中动态流量控制机制

提出一种边缘到边缘的动态流量控制机制-e2e-DFCM.e2e-DFCM工作原理是:发送端视频网关SVG对携带视频流质量标识QLI的报文聚集并重新进行QoS等级映射,接收端视频网关RVG周期地发送延迟、报文丢失等多播流状态信息;SVG根据QLI和RVG反馈的多播流状态信息对报文进行重新映射和分类,并基于效用动态分配各等级带宽,一旦接收端的服务质量不满足要求(平均延迟、丢失率超出承受范围),RVG甚至要求降级,SVG将降低发送速率.最后给出的模拟验证了e2e-DFCM机制的有效性.     

Path diversity for enhanced media streaming

Media streaming over best effort packet networks such as the Internet is quite challenging because of the dynamic and unpredictable available bandwidth, loss rate, and delay. Recently, streaming over multiple paths to provide path diversity has emerged as an approach to help overcome these problems. This article provides an overview of the benefits and use of path diversity for media streaming. The different approaches to media coding and streaming over multiple paths are examined, together with architectures for achieving path diversity between single or multiple senders and a single receiver. Important examples include using the distributed servers in a content delivery network to provide path diversity to a requesting client, using multiple 802.11 wireless access points to provide path diversity to a mobile client, and using relays to provide low-latency media communication. The design, analysis, and operation of media streaming systems that use path diversity are considered, with emphasis on the accurate performance models needed to select the best paths or best servers.     

A peer-to-peer architecture for media streaming

Given that the Internet does not widely support Internet protocol multicast while content-distribution-network technologies are costly, the concept of peer-to-peer could be a promising start for enabling large-scale streaming systems. In our so-called Zigzag approach, we propose a method for clustering peers into a hierarchy called the administrative organization for easy management, and a method for building the multicast tree atop this hierarchy for efficient content transmission. In Zigzag, the multicast tree has a height logarithmic with the number of clients, and a node degree bounded by a constant. This helps reduce the number of processing hops on the delivery path to a client while avoiding network bottlenecks. Consequently, the end-to-end delay is kept small. Although one could build a tree satisfying such properties easily, an efficient control protocol between the nodes must be in place to maintain the tree under the effects of network dynamics. Zigzag handles such situations gracefully, requiring a constant amortized worst-case control overhead. Especially, failure recovery is done regionally with impact on, at most, a constant number of existing clients and with mostly no burden on the server.     

Batched patch caching for streaming media

This letter elaborates on a scheme that combines batch patching at an origin server and prefix/interval caching at an edge server receiving the clients' requests. We derive a cost function that factors in the aggregate backbone rate, the cache occupancy, and the disk bandwidth utilization. We define the optimal batched patch caching strategy as a function of the client request rate. Finally, we show how various strategies including full caching, no caching and pure prefix caching with no patching are optimal derivations of our scheme under different request rates. We demonstrate the benefits of our scheme compared to classical streaming strategies     

基于Linux的流媒体传输

实时传输协议RTP在单点传输的网络服务上,提供端对端的网络传输功能,适合传输音视频、仿真数据.本文主要介绍了基于H.264的,在Linux下的实时传输系统构建的方法和步骤,以及RTP实时传输协议和H.264编码的视频源.     

基于Linux的流媒体传输基于Linux的流媒体传输

实时传输协议RTP在单点传输的网络服务上,提供端对端的网络传输功能,适合传输音视频、仿真数据。本文主要介绍了基于H．264的,在Linux下的实时传输系统构建的方法和步骤,以及RTP实时传输协议和H．264编码的视频源。     

TCP传输模式下高并发无线流媒体的控制与播放服务器的研究

针对流媒体服务高并发的要求,以及无线网络高误码率的特点,设计了一个采用TCP传输的"集中-分布式"无线流媒体服务器系统,并对设计进行了理论分析和实践检验,测试结果证明,该设计架构合理,可扩展性好,并发性能高,传输质量较为可靠,能够很好满足一类无线流媒体应用的需求.     

Adaptive streaming within the 3GPP packet-switched streaming service

The 3GPP packet-switched streaming service (PSS) is a standard for audio and video streaming to handheld 2.5G and 3G terminals and provides a complete streaming and download framework for commercial content. This article gives an overview of the PSS standard and in particular the support for adaptive streaming in PSS. We first describe the concept of streaming media and motivate the development of the PSS standard. Next, an introduction and overview of the PSS standard is given, followed by a detailed walkthrough of the adaptive streaming features. Finally, we present an example of 3GPP PSS-compliant adaptive streaming performed in a real client/server implementation. The proposed scheme is shown to be able to substantially improve the streaming quality under 2.5G and 3G network channel scenarios.     

Adaptive robust control of media advance systems for thermal inkjet printers

The inkjet printer offers an attractive feature set that fits well to the consumer’s needs at the low-end color hardcopy market. Better performance at a lower cost is and will always be the driving force for future product development. In this paper, an adaptive robust control is implemented to the media advance system in thermal inkjet printers to achieve designate objectives. Robust control guarantees the transient performance and final tracking error. The parameter adaptation also maintains asymptotic tracking. The experimental results indicate the excellent transient performance and final tracking accuracy.     

Adaptive available bandwidth estimation for internet video streaming

In this study, an adaptive available bandwidth estimation approach that is suitable for Internet video streaming is developed. The algorithm exploits repetitive measurements and uses this redundancy to improve its video adaptation decision. The importance of available bandwidth estimation in Internet applications has recently increased particularly because of the heterogeneity of the network links. Many of the Internet paths may contain wired and wireless links in which loss may happen due to congestion as well as link errors. Hence, loss rate by itself is not a sufficient statistics for monitoring purposes. If the loss is due to congestion, video quality can then be decreased whereas if the loss is due to link error, no such action is necessary. Moreover, in video streaming, such an estimate can be used to determine the new video rate if the quality is to be increased. In our approach, active probing packets are used to estimate bandwidth in very short time duration. The novelty of our estimator is its adaptivity in the sense that the overhead caused by the estimator is automatically reduced when congestion builds up. The trade off is reduced accuracy. Such accuracy is not needed under congestion anyway and when things get back to normal, our estimator turns back to normal operation mode. We have integrated our algorithm into our video streamer and carried out experiments on both simulated and actual streaming applications on the Internet. The results indicate that our estimator algorithm increases streaming performance substantially.     

基于mSCTP的移动流媒体传输方案研究

多网络覆盖的无线网络环境下由于存在路径选择和切换等机制,对于移动流媒体的传输方案有更高的要求,mSCTP协议是在流媒体控制传输协议SCTP的基础上增加了动态地址配置特性,可在用户移动的同时进行IP地址的动态增加和删减,从而选择最佳的传输路径,现结合mSCTP的动态地址配置特性和SCTP本身具有的多宿特性,提出一种在用户慢移动状态下,针对点播模式的移动流媒体业务的优化传输方案,制定传输路径选择策略,在主路径满足业务要求前提下不进行不必要的路径性能测试与切换,并通过NS2仿真验证.     

Optimal packet length scheduling for regulated media streaming

We present, for a prerecorded stream, an algorithm to determine a packet length schedule that is optimal with respect to appropriate measures of distortion and quality smoothness, when the traffic is required to adhere to specified token bucket regulation constraints.     

流媒体代理缓存技术的研究

随着Internet技术的发展和普遍应用,流媒体技术在Internet上得到了广泛的应用.对流媒体对象的访问,需要高且稳定的传送速率,网络带宽消耗大且持续时间长,容易给其他类型文件的访问带来影响,若用户过多,还会使初始流媒体服务器过载.代理缓存技术可帮助解决上述问题.文中介绍了流媒体代理缓存的特点,流媒体代理缓存的算法,流媒体代理缓存的评价指标和影响流媒体代理缓存效果的因素.     

Segment-based proxy caching for Internet streaming media delivery

The proliferation of multimedia content on the Internet poses challenges to existing content delivery networks. While proxy caching can successfully deliver traditional text-based static objects, it faces difficulty delivering streaming media objects because of the objects' sizes as well as clients' rigorous continuous delivery demands. We present two techniques supporting segment based proxy caching of streaming media. We evaluated these techniques in simulations and real systems.     

Proxy caching for media streaming over the Internet

Streaming media has contributed to a significant amount of today's Internet traffic. Like conventional Web objects (e.g., HTML pages and images), media objects can benefit from proxy caching; but their unique features such as huge size and high bandwidth demand imply that conventional proxy caching strategies have to be substantially revised. This article discusses the critical issues and challenges of cache management for proxy-assisted media streaming. We survey, classify, and compare the state-of-the-art solutions. We also investigate advanced issues of combining multicast with caching, cooperating among proxies, and leveraging proxy caching in overlay networks.     

A prefetching protocol for continuous media streaming in wirelessenvironments

Streaming of continuous media over wireless links is a notoriously difficult problem. This is due to the stringent quality of service (QoS) requirements of continuous media and the unreliability of wireless links. We develop a streaming protocol for the real-time delivery of prerecorded continuous media from (to) a central base station to (from) multiple wireless clients within a wireless cell. Our protocol prefetches parts of the ongoing continuous media streams into prefetch buffers in the clients (base station). Our protocol prefetches according to a join-the-shortest-queue (JSQ) policy. By exploiting rate adaptation techniques of wireless data packet protocols, the JSQ policy dynamically allocates more transmission capacity to streams with small prefetched reserves. Our protocol uses channel probing to handle the location-dependent, time-varying, and bursty errors of wireless links. We evaluate our prefetching protocol through extensive simulations with VBR MPEG and H.263 encoded video traces. Our simulations indicate that for bursty VBR video with an average rate of 64 kb/s and typical wireless communication conditions our prefetching protocol achieves client starvation probabilities on the order of 10^-4 and a bandwidth efficiency of 90% with prefetch buffers of 128 kbytes     

Multicasting streaming media to mobile users

Content distribution in general, and multicasting in particular, over a wired network to static hosts can be realized by placing proxies and gateways at several parts of the network. However, if the end hosts are mobile over heterogeneous wireless access networks, one needs to consider many operational issues such as network detection, handoff, join and leave latency, and desired level of quality of service, as well as caching and load balancing. This article surveys a set of protocols and technologies that offer multicast-based services for streaming multimedia in a mobile environment. It also brings forth some of the issues related to mobile content distribution in the wireless Internet that may be helpful during its deployment by application service providers.     

基于CDN的流媒体动态调度算法

采用指数分段缓存补丁块方案,根据媒体流行度更新缓存窗口大小,实现了流媒体对象在代理服务器中缓存的数据量和其流行度成正比的原则.仿真结果表明,该算法比MBP(multicast batched patching)算法和OBP(optimized batch patching)+prefix&patch caching算法具有更好的适应性,在最大缓存空间相同的情况下,能显著减少通过补丁通道传输的补丁数据,从而降低了服务器和骨干网络带宽的使用,同时节省了传输成本.     

Adaptive packet scheduling for scalable video streaming with network coding

Over the last decade, the emergence of new multimedia devices has motivated the research on efficient media streaming mechanisms that adapt to dynamic network conditions and heterogeneous devices’ capabilities. Network coding as a rateless code has been applied to collaborative media streaming applications and brings substantial improvements regarding throughput and delay. However, little attention has been given to the recoverability of encoded data, especially for the streaming with a strict deadline. This in turn leads to severe quality of experience. In this paper, we solve the unrecoverable transmission by proposing a multi-generation packet scheduling problem, which is treated as a video quality maximization problem and solved using dynamic programming algorithm. Experimental results confirm that the proposed algorithm brings better data recoverability and better quality of service in terms of video quality, delivery ratio, lower redundancy rate under different network sizes.