基于公安基层所队的视频会议系统的研究与设计

随着网络通信和多媒体技术的发展,人们已不满足简单的语音和文字通信,希望集语音、文字和图像于一体的多媒体通信。视频会议系统是一种应用网络技术和音频／视频编解码技术来实现虚拟会议的多媒体通信系统,能够使地理上分散的用P在网络上通过视频、声音、文本等信息流进行交互式的交流。     

多媒体通信技术及实验网

本文先介绍了多媒体与基础设施,然后讨论了多媒体通信网和多媒体系统分类及实现环境,最后介绍了一个多媒体学院网的应用实例。     

A Binding Architecture for Multimedia Networks

An open architecture that achieves seamless binding between networking and multimedia devices is proposed. The building blocks of the binding architecture consist of a set of interfaces, methods and primitives. The former abstract the functionalities of multimedia networking devices and are realized as objects organized into a binding interface base. The methods and primitives are invoked for implementing binding applications. The binding architecture is embedded into a reference model for multimedia networking architectures that supports a clean separation between binding interfaces and binding algorithms. Communication between the objects realizing the binding interfaces is supported by CORBA. Public interfaces in the binding interface base are specified using CORBA IDL. The architecture is illustrated with a simple connection management algorithm and an example of computational binding.     

A Survey of Application Layer Techniques for Adaptive Streaming of Multimedia

Though the integrated services model and resource reservation protocol (RSVP) provide support for quality of service, in the current Internet only best-effort traffic is widely supported. New high-speed technologies such as ATM (asynchronous transfer mode), gigabit Ethernet, fast Ethernet, and frame relay, have spurred higher user expectations. These technologies are expected to support real-time applications such as video-on-demand, Internet telephony, distance education and video-broadcasting. Towards this end, networking methods such as service classes and quality of service models are being developed. Today's Internet is a heterogeneous networking environment. In such an environment, resources available to multimedia applications vary. To adapt to the changes in network conditions, both networking techniques and application layer techniques have been proposed. In this paper, we focus on the application level techniques, including methods based on compression algorithm features, layered encoding, rate shaping, adaptive error control, and bandwidth smoothing. We also discuss operating system methods to support adaptive multimedia. Throughout the paper, we discuss how feedback from lower networking layers can be used by these application-level adaptation schemes to deliver the highest quality content.     

Optical networking chips get faster in a slow market

Tremendous network traffic growth, along with an increase in multimedia and other data-intensive traffic, has driven the potential need for high-performance networking technology offering transmission rates of 10 to 40 Gbits per second. Companies such as Internet exchange providers, which connect ISPs to one another, are currently buying 10-Gbps networking products. Companies such as Broadcom, Intel, and Quake Technologies are thus continuing to produce new, faster optical networking chips and hoping their business will turn around when the economy does.     

Group Decision Making on Urban Planning Using Desktop Multimedia Conferencing

Recent developments on multimedia systems and networking technology show that using desktop multimedia conferencing for group decision making on wide area networks such as the Internet is possible. In this paper we review the design, hardware and software requirements and organizational issues in a desktop multimedia conferencing system. We draw on our experiences from multiple multimedia conferences on the Internet and in particular we focus on a case study on urban planning using desktop multimedia conferencing on the Internet. Further we discuss implications for further research on desktop multimedia conferencing.     

Wireless MediaNets: application-driven next-generation wireless IP networks

Thanks to the explosive creation of multimedia contents, the pervasive adoption of multimedia coding standards and the ubiquitous access of multimedia services, multimedia networking is everywhere in our daily lives. Unfortunately, the existing best effort IP network infrastructure, originally designed with little real-time QoS requirement, has started to suffer from performance degradation on emerging multimedia networking applications. This inadequacy problem is further deepened by the prevalence of last/first-mile wireless networking, such as Wi-Fi, mobile WiMAX, and many wireless sensors and ad-hoc networks. This can be evidenced by more and more fragmentation of application-driven IP-based networks, such as for power grid distribution, networked security surveillance, intelligent transportation communication, and many other sensor networks. To overcome the QoS challenges, the next generation wireless IP networks have to be architected in a top-down manner, i.e., application-driven layered protocol design. More specifically, based on the application media data, compression schemes are applied, the subsequent Network, MAC- and PHY-layered protocols need to be accordingly or jointly enhanced to reach the optimal performance. This is the fundamental concept behind the design of Wireless MediaNets. In this survey paper, I will address the QoS challenges specifically encountered in video over heterogeneous wireless broadband networks and address several application-driven Wireless MediaNet solutions based on effective cross-layer integration of APP and MAC/PHY layers. More specifically, the congestion control for achieving airtime fairness of video streaming to maximize the link adaptation performance of Wi-Fi, the minimum latency event-driven data exchange for distributed wireless ad-hoc sensor networks, and the opportunistic multicast of scalable video live streaming over mobile WiMAX.     

基于SIP的多媒体通信网络构建

在多媒体网络上流动着数字数据、语音数据和视频数据,从而形成一个融合了语音、视频与数据三者的计算机多媒体通信网络。多媒体通信网络是许多网络专业工作者关心的技术,基于SIP的多媒体通信网络又是时下最流行组网方式。因此,就多媒体通信网络构建提出一些设计思路。     

Distributed computing architecture for effective management of multimedia streams on DPE

We study a networking architecture model that is built on a distributed processing environment (DPE) for multimedia services suitable for high speed transport networks such as ATM networks. In this architecture, the applications are deployed as units of software building blocks. Each building block provides a layered view for the effective management and control of the multimedia network resources and services according to the concept of telecommunications management network (TMN) and telecommunications information networking architecture (TINA). For the purpose of flexible service provision to users and effective service introduction by service providers, this architecture proposes the adoption of ad hoc service building blocks such as a video on demand building block and a CSCW building block that have interactions with a general purpose building block. This paper also proposes a naming structure for the management of user profiles and session profiles using a directory service system, and an effective control model for multimedia logical device objects using a stream process approach. The proposed model is implemented on a DPE platform that provides various transparencies, ANSAware.     

基于多媒体视讯技术的协同GIS平台研究

本文针对目前协同GIS发展趋势和多媒体视讯技术特点,提出多媒体视讯技术与协作型GIS的集成应用思想,构建了一种基于多媒体视讯技术的虚拟交流协同GIS工作平台框架。从管理模式,网络通信,信息共享,协作管理,协同工作,应用服务等方面,研究多媒体视讯技术在协作GIS中的功能与框架,协调与推动等问题,满足日益广泛的应用领域对GIS不断提高的要求。     

基于UPnP协议栈的嵌入式家庭媒体适配器的研究与设计*

研究并设计了一种基于UPnP协议的嵌入式家庭媒体适配器,它使传统的影音家电与网络媒体服务能够方便地互连,并实现零配置连接。该设计充分满足了数字家庭媒体内部和外部Internet的数据流和媒体流共享的需求。     

Multimedia P2P networking: Protocols, solutions and future directions

Due to the latest developments in electronics industry, multimedia communications is one of the key enabling technologies in the current and future networks. This special issue is to discuss advances in the state of the art and practice of multimedia P2P networking, as well as to identify the related emerging research topics. The careful evaluation process of this special issue has allowed us to select 8 high quality research papers. We strongly believe that the selected papers will make a significant contribution to researchers, practitioners, and students working in this field.     

Multicriteria decision making for enhanced perception-based multimedia communication

This paper proposes an approach that integrates technical concerns with user perceptual considerations for intelligent decision making in the construction of tailor-made multimedia communication protocols. Thus, the proposed approach, based on multicriteria decision making (MDM), incorporates not only classical networking considerations, but, indeed, user preferences as well. Furthermore, in keeping with the task-dependent nature consistently identified in multimedia scenarios, the suggested communication protocols also take into account the type of multimedia application that they are transporting. Lastly, this approach also opens the possibility for such protocols to dynamically adapt based on a changing operating environment and user's preferences.     

Transport protocol for real-time multimedia communication

With the advancements in multimedia and networking technologies, many distributed multimedia applications have been developed recently. These new applications rely on the underlying network support to transmit the multimedia real-time data between sites. Multimedia Transport Protocol (MMTP) is an experimental protocol designed for transmission of various multimedia data. MMTP uses multiple priority queues to support different levels of service requirements, and it discards packets from the transmission queue to reduce the network loading, and to ensure packets transmitted will meet the real-time constraint required by the data streams.     

一种新的等效带宽估计方法

网络技术和图像语音处理技术的发展促进了多媒体通信技术的发展,随着分级交换网中多媒体通信研究的深入,多媒体流的适时性问题得到了特别的关注,在实时多媒体应用中,同包丢失率一样,时延也是一个重要的性能指标,在综合考虑多媒体业务的统计特性以及包丢失率和时延等QoS参数影响的基础上,给出了一个计算简单且便于实时带宽估计和管理的多媒体业务等效带宽的近似表达式,并讨论了相关参数对等效带宽的影响。     

Multimedia Internet Rekeying for secure session mobility in ubiquitous mobile networks

Session mobility is one of new critical issues in the ubiquitous mobile networking environment. Session mobility provides a user changing its ongoing multimedia session, e.g., Voice-over-Internet Protocol (VoIP), from the currently using device to another by adapting user’s demand. In session Initial Protocol (SIP)-based multimedia services supporting session mobility, SIP serves as a signaling control protocol to negotiate session control, whereas media is transmitted using Real-time Transport Protocol (RTP). For securing multimedia sessions, Multimedia Internet Keying (MIKEY) is embedded in SIP signaling to negotiate security parameters for Secure RTP (SRTP), whereas SRTP is used to protect media stream. Since session mobility allows an ongoing multimedia session to be transferred from one device to another, a new security problem is raised, i.e., sensitive parameters may remain in the previous device when the ongoing multimedia session has been transferred to the current device. Unfortunately, current MIKEY cannot bear the aforementioned security problem in session mobility. Therefore, we propose Multimedia Internet Rekeying (MIRKEY) for session mobility in the ubiquitous mobile networking environment. Although MIKEY can be executed again to carry out the rekeying of the session key and Crypto Session bundle (CSB) update, the sensitive parameters still remain in previous devices. MIRKEY contains a SBK to bind the participated user and multimedia session. Besides, SBK can persist in rekeying based on the key chain whenever a multimedia session is transferred to other devices. As a result, SBK is operative only in the specific device. As a result, MIRKEY can solve the newly raised security problem in session mobility. Furthermore, we verify MIRKEY using Burrows–Abadi–Needham (BAN) logic and realize it in the implemented ubiquitous multimedia service platform (UMSP).     

分布式多媒体教学信息传输控制系统

研究了“分布式多媒体教学信息传输控制系统”的体系结构、信息传输控制过程和实现方法,并对视频编解码技术和网络编程技术进行了详细探讨。     

基于平台化实践教学体系的软件工程应用型人才培养模式

针对软件实用型人才培养目标,提出一种基于平台化实践教学体系的软件工程应用型人才培养模式应用计算机、多媒体和网络信息化等多种现代化教学手段,并与传统教学手段相结合,搭建不同层次的多维实践教学平台,培养学生的知识综合应用能力、工程实践能力和创新实践能力。     

多媒体信息网络实时传输的应用研究

论述了基于MPEG－I的编解码国际标准和TCP／IP网络协议,多媒体信息在网络环境下的实时传输,并对视频编解码技术和网络编程技术进行了探讨。给出了一个多媒体网络实时监控系统的实例,介绍了它的功能、体系结构和核心模块的设计与实现。     

Computer communications TC

To fully realise the promise of emerging high speed networks we need: high bandwidth applications; networking standards; and networking services based on those standards. Two service models are being pursued to support high speed multimedia applications: IETF (Internet Engineering Task Force) and ATM (asynchronous transfer mode). The authors compare these models. They then discusses the future activities of the Computer Communications Technical Committee in this regard