无线视频流编码与传输技术初探

针对无线信道的特性和多种无线终端并存的现实,探讨了在时变无线网络中向多种客户终端传送视频流的关键技术,介绍了分级视频编码和逐级加密技术的综合运用,并给出了一种新的无线视频流传输方案。     

流媒体传输中的视频编码技术

概述了流媒体广播的系统结构和主要技术,介绍了流媒体中的视频编码技术,主要分析了精细可分级编码(FGSC)和渐进精细可分级编码(PFGSC)两种编码方法的原理与实现。     

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.     

Network-Adaptive Video Communication Using Packet Path Diversity and Rate-Distortion Optimized Reference Picture Selection

In this paper, we present error-resilient Internet video transmission using path diversity and rate-distortion optimized reference picture selection. Under this scheme, the optimal packet dependency is determined adapting to network characteristics and video content, to achieve a better trade-off between coding efficiency and forming independent streams to increase error-resilience. The optimization is achieved within a rate-distortion framework, so that the expected end-to-end distortion is minimized under the given rate constraint. The expected distortion is calculated based on an accurate binary tree modeling with the effects of channel loss and error concealment taken into account. With the aid of active probing, packets are sent across multiple available paths according to a transmission policy which takes advantage of path diversity and seeks to minimize the loss rate. Experiments demonstrate that the proposed scheme provides significant diversity gain, as well as gains over video redundancy coding and the NACK mode of conventional reference picture selection. Yi Liang received the Ph.D. degree in Electrical Engineering from Stanford University in 2003. His expertise is in the areas of networked multimedia systems, real-time voice and video communication, and low-latency media streaming over the wire-line and wireless networks. Currently holding positions at Qualcomm CDMA Technologies, San Diego, CA, he is responsible for video and multimedia system design and development for Qualcomm's mobile station modem (MSM) chipsets. From 2000 to 2001, he conducted research with Netergy Networks, Inc., Santa Clara, CA, on voice over IP systems that provide improved quality over best-effort networks. From 2001 to 2003, he had been the lead of the Stanford - Hewlett-Packard Labs low-latency video streaming project, in which he and his colleagues developed error-resilience techniques for rich media communication over IP networks at low latency. In the summer of 2002 at Hewlett-Packard Labs, Palo Alto, CA, he developed an accurate loss-distortion model for compressed video and contributed in the development of the mobile streaming media content delivery network (MSM - CDN) that delivers rich media over 3G wireless. Yi Liang received the B. Eng. degree from Tsinghua University, Beijing, China. Eric Setton received the B.S. degree from Ecole Polytechnique, Palaiseau, France in 2001 and the M.S. degree, in Electrical Engineering from Stanford University in 2003. He is currently a Ph.D. candidate in the department of Electrical Engineering of Stanford University and is part of the Image, Video and Multimedia Systems group. Multimedia communication over wired and wireless networks, video compession and image processing are his main research interests. In 2001, he received the Carnot fellowship and the SAP Stanford Graduate fellowship. In 2003, he received the Sony SNRC fellowship. He has spent time in industry in France at SAGEM and in the United States at HP labs and at Sony Electronics. He has 4 patents pending. Bernd Girod is Professor of Electrical Engineering in the Information Systems Laboratory of Stanford University, California. He also holds a courtesy appointment with the StanfordDepartment of Computer Science and he serves as Director of the Image Systems Engineering Program at Stanford. His research interests include networked media systems, video signal compression and coding, and 3-d image analysis and synthesis. He received his M.S. degree in Electrical Engineering from Georgia Institute of Technology, in 1980 and his Doctoral degree “with highest honours” from University of Hannover, Germany, in 1987. Until 1987 he was a member of the research staff at the Institut fur Theoretische Nachrichtentechnik und Informationsverarbeitung, University of Hannover, working on moving image coding, human visual perception, and information theory. In 1988, he joined Massachusetts Institute of Technology, Cambridge, MA, USA, first as a Visiting Scientist with the Research Laboratory of Electronics, then as an Assistant Professor of Media Technology at the Media Laboratory. From 1990 to 1993, he was Professor of Computer Graphics and Technical Director of the Academy of Media Arts in Cologne, Germany, jointly appointed with the Computer Science Section of Cologne University. He was a Visiting Adjunct Professor with the Digital Signal Processing Group at Georgia Institute of Technology, Atlanta, GA, USA, in 1993. From 1993 until 1999, he was Chaired Professor of Electrical Engineering/Telecommunications at University of Erlangen-Nuremberg, Germany, and the Head of the Telecommunications Institute I, co-directing the Telecommunications Laboratory. He has served as the Chairman of the Electrical Engineering Department from 1995 to 1997, and as Director of the Center of Excellence “3-D Image Analysis and Synthesis” from 1995-1999. He has been a Visiting Professor with the Information Systems Laboratory of Stanford University, Stanford, CA, during the 1997/98 academic year. As an entrepreneur, Prof. Girod has worked successfully with several start-up ventures as founder, investor, director, or advisor. Most notably, he has been a co-founder and Chief Scientist of Vivo Software, Inc., Waltham, MA (1993–98); after Vivo's aquisition, 1998-2002, Chief Scientist of RealNetworks, Inc. (Nasdaq: RNWK); and, from 1996–2004, an outside Director of 8 × 8, Inc. (Nasdaq: EGHT). Prof. Girod has authored or co-authored one major text-book, two monographs, and over 250 book chapters, journal articles and conference papers in his field, and he holds about 20 international patents. He has served as on the Editorial Boards or as Associate Editor for several journals in his field, and is currently Area Editor for Speech, Image, Video and Signal Processing of the “IEEE Transactions on Communications.” He has served on numerous conference committees, e.g., as Tutorial Chair of ICASSP-97 in Munich and ICIP-2000 in Vancouver, as General Chair of the 1998 IEEE Image and Multidimensional Signal Processing Workshop in Alpbach, Austria, and as General Chair of the Visual Communication and Image Processing Conference (VCIP) in San Jose, CA, in 2001. Prof. Girod has been a member of the IEEE Image and Multidimensional Signal Processing Committee from 1989 to 1997 and was elected Fellow of the IEEE in 1998 ‘for his contributions to the theory and practice of video communications.’ He has been named ‘Distinguished Lecturer’ for the year 2002 by the IEEE Signal Processing Society. Together with J. Eggers, he is recipient of the 2002 EURASIP Best Paper Award.     

Energy-Efficient Routing Algorithms Using Directional Antennas for Mobile Ad Hoc Networks

Power consumption is an important issue in the wireless ad hoc networking environment. In this paper, we present several energy-efficient routing algorithms using directional antennas for wireless ad hoc networks. These algorithms are simple to implement and are distributed and can be applied to mobile environments. We evaluate how directional antennas improve system throughput. We study the influence of the battery recovery effect and mobility on the network throughput during a network lifetime. We also present an algorithm that exploits the broadcast nature of the wireless communication environment to improve end-to-end bit error performance for a Rayleigh fading channel.     

基于OpenFlow的SVC流媒体时延自适应分级传输方法

针对当前互联网流媒体传输的时延敏感性问题,提出一种基于OpenFlow的SVC（scalable video coding,可分级视频编码）流媒体时延自适应分级传输方法,该方法有效结合SVC流媒体可分级和OpenFlow灵活可编程的特性,在网络带宽受限和链路拥塞的复杂网络环境下,通过构建基础层和增强层2个独立路由,实现了动态网络下SVC流媒体分级自适应高效传输。仿真结果表明,该方法在提升SVC流媒体传输效率和质量,改善用户体验方面有重要作用。     

基于联合信源信道编码的视频流传输

介绍了目前在多媒体通信系统中提出的一个新思想一联合信源／信道编码方法，以及基于该方法的视频流传输技术。分析介绍了联合信源／信道编码方法的分类和不同于以往传统通信系统设计方法的特点及优越性。并且针对多媒体传输应用中的视频流传输方法，分类比较了几种典型的系统结构，描述了其优缺点。     

一种有效降低误差扩散的数据分割方法

提出一种有效降低误差扩散的数据分割方法.该方法改进了H.264划分子流的做法,采用当前编码宏块被错误解码时对下一编码帧产生的误差扩散程度来判别该宏块的优先级,以此划分不同的传输子流.在给定网络带宽和丢包率的情况下,采用率失真优化的码率分配算法对不同传输子流分别施以不同的信道编码保护力度,以保证在相同传输条件下,优先级高的宏块被正确接收的概率最大化,使重建视频流的质量达到最优.该方法实现简单,对宏块的分类更加合理,有效降低了由于包丢失引起的误差扩散效应,改善了重建视频的质量.实验结果表明在相同的带宽和丢包率条件下,本文方法比H.264方法提高视频接收质量大约0.3~0.6dB.     

IP组播技术及其在视音频传输中的应用

主要阐述有关IP组播技术的基本概念、组播树、路由协议等,探讨利用IP组播实现视频传输的条件、QoS、关键技术,并展望了该项技术的前景.     

移动流媒体——3G时代信息名址新服务展望

随着3G时代的到来,信息名址将借助移动流媒体的形式,为用户提供更加丰富多彩的服务。本文介绍了信息名址移动流媒体业务的形式、系统结构以及移动流媒体的音/视频编码技术,分析了信息名址移动流媒体技术与业务的发展前景。     

虚拟现实视频处理与传输技术

虚拟现实(VR)是当前视频领域研究热点.介绍了VR视频内容制作以及终端显示技术现状,分析了基于用户视点的VR视频处理关键技术,最后探讨了VR视频传输模式及其对承载网络的需求.     

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.     

MUSICAM编码器的技术特点

本文讨论了DAB音频处理和编码的原理，并分析了MUSICAM编码的技术特点。     

多跳无线局域网视频质量优化的路由与源码率控制

使用以视频质量为中心的跨层设计思想,把应用层视频质量建模为网络层行为的函数,将用于视频传输的多跳无线局域网的结点带宽分配问题归结为整个网络范围内的流传输路径选择和码率控制问题,带宽调度优化的目标是使接收端总解码视频质量最佳,给出一个基于遗传算法的启发式方案以求解该优化问题并证明了算法的有效性.