基于FlashMediaServer的HTTP动态视频流技术

HTTP动态流技术是Adobe公司伴随FlashMediaServer4．5推出的一项最新的HTTP渐进下载技术,FlashMediaServer4．5能够将实时或预先录制的内容打包至可高速缓存的碎片中,这样可以支持完全的流媒体功能,结合HTTP动态流技术,充分利用现有的HTTP基础设施的优势,通过对视频源文件的特殊处理,可以将多比特率Flash流媒体内容更方便地呈现给流媒体用户,改善并提升用户的视频体验质量。     

基于机器学习的HTTP视频业务分类

随着多媒体技术的发展,优酷等HTTP视频业务占据越来越大的网络流量。对HTTP视频业务进行有效分类以保证其QoS已成为必要。然而大多数HTFP视频业务以浏览器为客户端,通过端口号难以将HTTP视频业务和其他Web业务区分开来。本文采用机器学习方法对HTTP视频业务进行区分,通过采用流组特征使得识别准确率提高了12％,并对三种机器学习     

有限带宽网络视频流传输速率控制策略研究

为促进公共视频监控领域新技术的开发和应用,立足解决工程实际问题,提出了一种有限带宽网络下视频流传输速率的控制策略。系统可以根据数据包丢失率、传输时间和时限等动态参数对网络带宽进行估测,并对实时视频的发送速率进行自适应调整,实现稳健控制,很好地解决了网络的传输带宽与视频流码率不匹配等问题。仿真实验表明,系统在降低视频时延和包丢失率、减少网络拥塞、提高带宽利用率和改善视频质量等方面效果明显。     

一种基于HTTP长连接的自适应流媒体传输系统

提出了一种基于HTTP的自适应流媒体传输系统,一方面,该系统利用了HTTP长连接技术,有效地减少了频繁建立与断开TCP连接带来的网络资源开销;另一方面,该系统采用了一种服务器端驱动的码率自适应控制策略,这种策略不仅有效地适应于网络环境的变化,还降低了对客户端的要求,具有很强的通用性。实验结果表明该系统方案是有效的。     

浅论自适应码率视频流的原理及在 OTT中应用简

OTT视频应用已经成为业界发展趋势,但其网络环境却缺少QOE（Quality of experience）保证。因此在提供OTT业务时,用户使用体验QOE变得至关重要。在无线网络环境下,由于无线频谱资源的稀缺性,优化OTT视频能够节省宝贵的无线网络资源。本文通过介绍自适应码流的原理及在OTT中的应用,说明自适应码流技术在OTT环境中的重要应用价值。     

UMTS网络仿真中基于OPNET的HTTP业务建模

提供快速有效的Internet接入是UMTS网络的重要目标。当今,HTTP业务是构成Internet业务的主要部分,因此有必要研究UMTS网络承载HTTP业务时的性能。文章介绍了HTTP业务模型的基本概念,模型各层次服从的概率分布。随后给出了OPNET平台上一种HTTP业务模型的实现、模型状态机各状态的功能及模型,并讨论了业务模型和无线网络特性之间的相互影响。     

对主流自适应码率流媒体技术的分析

伴随着互联网多媒体应用的快速增长,尤其是在线视频业务的不断发展,传统的流媒体技术由于其单一的编码方式难以适应差异化的用户网络变化,极大地影响了用户体验。分析了当前在线视频业务面临的主要问题,同时介绍了新兴的自适应码率流媒体技术的特点和优势。通过对主流自适应码率流媒体和传统流媒体技术的分析和比较,表明对于OTT业务而言,标准化的自适应码率流媒体技术比传统的流媒体技术更加有优势。     

基于SDR的HSPA+网络规模化应用实例

中兴通讯为香港CLS提供的融合网络解决方案,是中兴SOR平台的首次大规模部署的应用实例.从实际效果角度分析了SDFI平台在网络平滑演进、高带宽、低功耗、多模式等方面所具备的能力和优势.     

Android移动终端数据同步技术研究与应用

随着Android智能手机平台在市场的占有率越来越高,基于Android的增值业务也越来越丰富,同时使用SyncML数据同步协议,可以将网络数据通过多种设备同步化,用户个人信息能够在不同设备上得到更新和保持一致,因此,两者的结合无疑是一种新的,并且具有巨大商业价值的研究。文章首先阐述了Android软件平台的系统架构,接着详细分析了SyncML数据同步协议,最后将以上两种技术接合在一起,实现了基于vCard协议和HTTP传输协议的联系人数据同步。     

广播直播中HSPA+无线接入技术的应用

本文简要介绍了在三网融合背景下应用HSPA+等无线接入技术构建现代传播体系,创新广播直播模式,提升节目音频质量的实践。介绍了相关技术设备及方案,进行了测试并对结果进行分析。     

Design and Implementation of a Network‐Adaptive Mechanism for HTTP Video Streaming

This paper proposes a network‐adaptive mechanism for HTTP‐based video streaming over wireless/mobile networks. To provide adaptive video streaming over wireless/mobile networks, the proposed mechanism consists of a throughput estimation scheme in the time‐variant wireless network environment and a video rate selection algorithm used to increase the streaming quality. The adaptive video streaming system with proposed modules is implemented using an open source multimedia framework and is validated over emulated wireless/mobile networks. The emulator helps to model and emulate network conditions based on data collected from actual experiments. The experiment results show that the proposed mechanism provides higher video quality than the existing system provides and a rate of video streaming almost void of freezing.     

HTTP自适应流媒体直播系统中的用户体验质量优化

分析HTTP自适应流媒体直播系统中对终端用户体验质量(QoE)产生影响的各类因素及其相互之间的作用关系,对基于服务器端、网络传输以及客户端的QoE优化策略进行总结。认为HTTP自适应流媒体直播系统的QoE优化重点在于降低延时,提出结合网络层和应用层影响因素来降低时延并提升用户QoE的建议。     

针对移动视频流介于UMTS和WiMAX网络间的切换方案

下一代移动网络(NGMN)倾向于融合多个无线接入技术(RATs)来为用户提供无处不在的访问服务。而作为一个无处不在系统,能够有一个解决方案来支持日益流行的视频应用程序也是至关重要的。由于移动视频应用程序的高带宽要求和对延迟敏感的特点,如何让移动视频应用程序在不同的RATs之间进行无缝切换并保证服务质量(QoS)是我们面临的一个挑战。为了加快实现在异构网络中提供无缝视频流服务,通过运用IEEE 802.21规定的媒体独立信息服务的服务器提出了一种移动端发起-网络端控制的移动网络切换方案。仿真结果表明,该方案在丢包率、延迟和峰值信噪比等方面提高了性能。     

Estimating Reduced-Reference Video Quality for Quality-Based Streaming Video

Reduced-reference (RR) video-quality estimators send a small signature to the receiver. This signature comprises the original video content as well as the video stream. RR quality estimation provides reliability and involves a small data payload. While significant in theory, RR estimators have only recently been used in practice for quality monitoring and adaptive system control in streaming-video frameworks. In this paper, we classify RR algorithms according to whether they are based on a) modeling the signal distortion, b) modeling the human visual system, or c) analyzing the video signal source. We review proposed RR techniques for monitoring and controlling quality in streaming video systems.     

Seamless Streaming Media for Heterogeneous Mobile Networks

As the mobile networking technologies evolve, people are able to access the Internet through heterogeneous wireless access networks, such as WLAN, GPRS, 3G and Beyond 3G networks. For the coverage, bandwidth and cost of these heterogeneous mobile access networks are quite different, a mobile host may hand over among them, and this is called vertical handoffs. One of the most important issues for heterogeneous mobile networks is that vertical handoffs may degrade the quality of the time-sensitive streaming media services, even interrupt them. To overcome the problem, in the paper a multicast-based redundant streaming architecture is proposed. The proposed architecture is implemented in the all-IPv6 heterogeneous mobile networks. Five experiments are performed to evaluate the performance of the proposed architecture. The experimental results and the analysis show that the proposed architecture is capable of providing seamless streaming services even if the vertical handoffs or the traffic congestion occurs. Moreover, it is found that the traffic overhead is only 1.0368% per vertical handoff for each mobile access network, and thus the feasibility of the proposed architecture is demonstrated.

Link Error Analysis and Modeling for Video Streaming Cross‐Layer Design in Mobile Communication Networks

Particularly in wireless communications, link errors severely affect the quality of the services due to the high error probability and the specific error characteristics (burst errors) in the radio access part of the network. In this work, we show that thorough analysis and appropriate modeling of radio‐link error behavior are essential to evaluate and optimize higher layer protocols and services. They are also the basis for finding network‐aware cross‐layer processing algorithms which are capable of exploiting the specific properties of the link error statistics, such as predictability. This document presents the analysis of the radio link errors based on measurements in live Universal Mobile Telecommunication System (UMTS) radio access networks as well as new link error models originating from that analysis. It is shown that the knowledge of the specific link error characteristics leads to significant improvements in the quality of streamed video by applying the proposed novel network‐ and content‐aware cross‐layer scheduling algorithms. Although based on live UMTS network experience, many of the conclusions in this work are of general validity and are not limited to UMTS only.     

A Video Streaming System for Mobile Phones: Practice and Experience

This paper presents a case of video streaming system for mobile phone which has actually been implemented and deployed for commercial services in CDMA2000 1X cellular phone networks. As the computing environment and the network connection of cellular phones are significantly different from the wired desktop environment, the traditional desktop streaming method is not applicable. Therefore, a new architecture is required to suit the successfully streaming in the mobile phone environment. We have developed a very lightweight video player for use in mobile phone and the related authoring tool for the player. The streaming server has carefully been designed to provide high efficiency, reliability and scalability. Based on a specifically-designed suite of streaming protocol, the server employs an adaptive rate control mechanism which transmits the media packets appropriately into the network according to the change in network bandwidth.Hojung Cha is currently a professor in computer science at Yonsei University, Seoul, Korea. His research interests include multimedia computing system, multimedia communication networks, wireless and mobile communication systems and embedded system software. He received his B.S. and M.S. in computer engineering from Seoul National University, Korea, in 1985 and 1987, respectively. He received his Ph.D. in computer science from the University of Manchester, England, in 1991.Jongmin Lee is a Ph.D. candidiate in computer science at Yonsei University, Seoul, Korea. His research interests include wireless multimedia system, QoS architecture, multimedia communication networks. He received his B.S. and M.S. in computer science from Kwangwoon University in 1999 and 2001, respectively.Jongho Nang is a professor in the Department of Computer Science at Sogang University. He received his B.S. degree from Sogang University, Korea, in 1986 and M.S. and Ph.D. degree from KAIST, in 1988 and in 1992, respectively. His research interests are in the field of multimedia systems, digital video library, and Internet technologies. He is a member of KISS, ACM, and IEEE.Sung-Yong Park is an associate professor in the Department of Computer Science at Sogang University, Seoul, Korea. He received his B.S. degree in computer science from Sogang University, and both the M.S. and Ph.D. degrees in computer science from Syracuse University. From 1987 to 1992, he worked for LG Electronics, Korea, as a research engineer. From 1998 to 1999, he was a research scientist at Telcordia Technologies (formerly Bellcore) where he developed network management software for optical switches. His research interests include high performance distributed computing and systems, operating systems, and multimedia.Jin-Hwan Jeong received the B.S. and M.S. degrees in computer science from Korea University, Seoul, Korea, in 1997, and 1999, respectively. He is currently in Ph.D. course at Korea University. His research interests include video processing for thin devices, multimedia streaming and operating systems.Chuck Yoo received the B.S. degree in electronics engineering from Seoul National University, Seoul, Korea and the M.S. and Ph.D. in computer science in University of Michigan. He worked as a researcher in Sun Microsystems Lab. from 1990 to 1995. He joined the Computer Science and Enginnering Department, Korea University, Seoul, Korea in 1995, where he is currently a professor. His research interests include high performance network, multimedia streaming, and operating systems.Jin-Young Choi received the B.S. degree from Seoul National University, Seoul, Korea, in 1982, the M.S. degree from Drexel University in 1986, and the Ph.D. degree from University of Pennsylvania, in 1993. He is currently a professor of Computer Science and Engineering Department, Korea University, Seoul, Korea. His current research interests are in real-time computing, formal methods, programming languages, process algebras, security, software engineering, and protocol engineering.     

基于中继的OFDMA网络中可扩展编码视频流传输的权衡优化(英文)

To achieve an optimal trade-off between video quality and energy efficiency in the uplink streaming of multi-user Scalable Video Coding (SVC) videos in relay-based Orthogonal Frequency Division Multiple Access (OFDMA) cellular networks, a cross-layer design framework that jointly selects the Transmission Policy (TP) for SVC video frames, assigns OFDMA subcarriers, and allocates power for each subcarrier is proposed. We apply the dual decomposition method to the problem, and obtain a TP selection subproblem for each SVC video adaptation and a resource allocation subproblem of Joint Subcarrier, Relay and Power Allocation (JSRPA). A second level of dual decomposition is used to divide the JSRPA problem into independent subcarrier subproblems. The proposed Crosslayer Trade-off Optimization (CTO) algorithm is sub-distributed with significantly low complexity. A performance evaluation with typical SVC video traces demonstrates that the proposed algorithm is able to converge and efficiently achieve the optimal trade-off between the video quality and energy consumption at the MSs for uplink SVC streaming.     

Battery-Aware Routing for Streaming Data Transmissions in Wireless Sensor Networks

Recent technological advances have made it possible to support long lifetime and large volume streaming data transmissions in sensor networks. A major challenge is to maximize the lifetime of battery-powered sensors to support such transmissions. Battery, as the power provider of the sensors, therefore emerges as the key factor for achieving high performance in such applications. Recent study in battery technology reveals that the behavior of battery discharging is more complex than we used to think. Battery powered sensors might waste a huge amount of energy if we do not carefully schedule and budget their discharging. In this paper we study the effect of battery behavior on routing for streaming data transmissions in wireless sensor networks. We first give an on-line computable energy model to mathematically model battery discharge behavior. We show that the model can capture and describe battery behavior accurately at low computational complexity and thus is suitable for on-line battery capacity computation. Based on this battery model we then present a battery-aware routing (BAR) protocol to schedule the routing in wireless sensor networks. The routing protocol is sensitive to the battery status of routing nodes and avoids energy loss. We use the battery data from actual sensors to evaluate the performance of our protocol. The results show that the battery-aware protocol proposed in this paper performs well and can save a significant amount of energy compared to existing routing protocols for streaming data transmissions. Network lifetime is also prolonged with maximum data throughput. As far as we know, this is the first work considering battery-awareness with an accurate analytical on-line computable battery model in sensor network routing. We believe the battery model can be used to explore other energy efficient schemes for wireless networks as well.     

基于跨层码率适配和差错控制的3D视频无线传输方法

针对纹理视频加深度序列的3D视频无线传输,本文提出一种基于跨层优化的码率适配和差错控制方法.通过最小化端到端3D视频失真,均衡调整和配置应用层3D视频编码的码率和帧内编码更新比例,以及物理层的调制和编码模式,达到信源码率适配信道带宽以及应用层差错控制和物理层信道保护强度相互平衡的目的,进而提高接收端的3D虚拟视点视频质量.实验结果表明,提出的方法能有效的提高3D视频无线传输的性能.