Prototyping of VLSI components from a formal specification

A trajectory from formal specification to component is presented, which can be used to prototype applications which combine off-the-shelf components and custom hardware, provided they meet the constraints of Synchronous Data Flow. The formal specification allows one to prove that custom components will be correctly synchronized in a system context. VLSI Synchronous Data Flow is introduced, the constraints it imposes are elaborated, and functions relevant to constructing a system are defined. Then, a component for motion video coding in VHDL is developed and synthesized, starting from a formal specification.This work was partially funded by the French Coordinated Research Program ANM of the French Ministry of Research and Space, by the Esprit BRA project No 6632 NANA-2, and by the Doctoral-candidate Network for System and Machine Architecture of the DRED.     

Specifying and authoring multimedia scenarios

An authoring methodology and a set of checking tools let authors specify the spatial and temporal features of an application and verify the application prior to its execution. The checking tools include an animation tool, spatial and temporal layouts, and the execution table of the application     

An informal overview of formal protocol specification

A RAPIDLY GROWING area of research in computer communications is formal protocol specification. The importance of protocols arises from the fact that protocols form the nervous system of teleprocessing networks and, as such, are responsible for ensuring that the pieces of the system work as a harmonious whole. The complexity and size of today's systems and the fact that they are put together from subsystem components manufactured in different locations and even by different companies, virtually demand formal specification. And, there are many side benefits, as this tutorial points out.     

MultiSync: a synchronization model for multimedia systems

Synchronization among various media sources is one of the most important issues in multimedia communications and various audio/video (A/V) applications. For continuous playback (such as lip synchronization) under a time-sharing multiprocessing operating system (such as UNIX), the synchronization quality of traditional synchronization mechanisms employed on single processes may vary according to the workload of the system. When the system encounters an overload situation, the synchronization usually fails and, even worse, results in two fatal defects in human perception: the audio discontinuity (audio break) and the out-of-synchronization (synchronization anomaly). In order to overcome these problems, a novel media synchronization model employed on multiple processes (or threads) in a multiprocessing environment is proposed. The problem of asynchronism due to system overload is solved by assigning a higher priority to more important media and adopting a delay-or-drop policy to treat the lower priority ones. Some experimental results are presented to show the effectiveness of the proposed model and the implementation mechanisms under a UNIX, X-Windows environment. On the basis of the proposed model, a continuous media playback (CMP) module, which acted as the key component of some popular multimedia systems such as multimedia authoring system, multimedia E-mail system, multimedia bulletin board system (BBS), and video-on-demand (VoD) System, was implemented     

Media synchronization in multimedia Web using a neuro-fuzzyframework

We consider the problem of multimedia synchronization in a Web environment. The workload generated by the multimedia server during a Web session exhibits variations that are quite different from the traffic fluctuation offered by a single media stream, e.g., a variable bit rate (VBR) video. We propose a set of parameters that can be used to characterize the workload generated by the multimedia server in a Web-type browsing environment. The workload characterization scheme is subsequently used in designing a server-based synchronization scheme. The problem of scheduling multimedia information to ensure media synchronization in a Web environment is identified as a multicriteria scheduling problem, which is NP-hard. The ability of fuzzy control to deal with multivariables makes it a good alternative for the multicriteria scheduling problem considered. Consequently, we propose a neuro-fuzzy scheduler (NFS) that makes an intelligent compromise among multicriteria by properly combining some scheduling heuristics. Performance of the NFS is compared with several known heuristics and a branch and bound algorithm. The results show that the proposed NFS ran dynamically adjust to the varying workload quite well     

安全策略模型规范及其形式分析技术研究

形式化是开发高安全等级计算机系统的核心技术之一,但目前形式开发方法无法直接借助于机器证明获得较之手工证明更加严格的安全策略模型正确性保证,以及安全策略模型和安全功能规范之间的精确对应.通过把安全功能规范开发技术应用于安全策略模型的开发中,提出了一种新颖的安全策略模型形式规范构造方法及其证明机理,从而有效解决了上述问题.还以Bell-LaPadula多级安全策略为实例,具体说明了规范的形式开发和形式分析过程.     

Quality-based evaluation of multimedia synchronization protocolsfor distributed multimedia information systems

Distributed, networked multimedia information systems will be a critical component of technology-based information infrastructures in the future. We present an infrastructure for supporting multimedia applications. We discuss various characteristics of multimedia data and the effect of the network on the required quality of presentation for multimedia data. We present a suite of synchronization protocols to support the quality of presentation. The crux of these protocols is the scheduling of multimedia information for synchronized delivery, over broadband networks with limited resources, and is identified as an NP-hard problem. We introduce two parameters which can be used to measure the performance of end-to-end synchronization protocols in a network supporting distributed multimedia applications. We propose and implement several heuristic scheduling algorithms, and compare their performance. We deduce the appropriateness of these algorithms in different types of distributed multimedia environments     

A temporal model for interactive multimedia scenarios

Many authoring tools let authors create scenarios, but very few let them create an active multimedia scenario that will not only play itself back, but will change course dynamically, depending on user interactions. Our temporal model provides a new way to represent asynchronous and synchronous temporal events, allowing authors to create scenarios that offer viewers seamless, transparent options     

A temporal reference framework for multimedia synchronization

The synchronization problem for audio/visual reproduction has consumed engineers time since the advent of recorded audio and images and the first multimedia productions. As computers have evolved to support programmed reproduction of multimedia information, the complexity but not the character or interest have changed. In the digital domain, synchronization problems exist due to data distribution and communications, random events caused by human-computer interaction, and general computer and communications performance limitations. This rich research domain has led to numerous approaches to the modeling and execution of multimedia synchronization scenarios. Unfortunately, these approaches are difficult to compare and evaluate due to their varied theoretical bases and modeling techniques. We develop a uniform, theoretical foundation for discussing multimedia synchronization and temporal specification. We propose a temporal reference framework and use it to compare existing temporal specification schemes and their relationships to multimedia synchronization. The ensuing comparison of existing specification and synchronization techniques demonstrates the utility of the framework     

《信息技术 便携式数字音视频播放器通用规范》标准解读

主要就<信息技术便携式数字音视频播放器通用规范>行业标准中的一些术语和关键条款进行了解读,着重介绍了产品的容量.速度和产品的指标等标准内容.     

The specification of the temporal behaviour for multimedia scheduling

In this paper, we present a timing model for describing the temporal behaviour of a multimedia application. This timing model is based on the so called temporal profiles. After illustrating such a notion through examples, we specify formally temporal profiles and the scheduling problem through a relation between temporal profiles.     

QoS specification languages for distributed multimedia applications: a survey and taxonomy

Following considerable research into quality-of-service-aware application programming interface design and QoS specification language development for multimedia systems, we present a survey and taxonomy of existing QoS specification languages. As computer and communication technology evolves, distributed multimedia applications are becoming ubiquitous, and quality of service (QoS) is becoming ever more integral to those applications. Because they consume so many resources (such as memory and bandwidth), multimedia applications need resource management at different layers of the communications protocol stack to ensure end-to-end service quality, and to regulate resource contention for equitable resource sharing. However, before an application can invoke any QoS-aware resource management mechanisms and policies - such as admission control, resource reservation, enforcement, and adaptation - it must specify its QoS requirements and the corresponding resource allocations. Furthermore, the application must describe how QoS should be scaled and adapted in cases of resource contention or resource scarcity during runtime. Our goal in this article is to systematically classify and compare the existing QoS specification languages that span several QoS layers with diverse properties. The provided taxonomy and the extensive analysis will give us a detailed look at the existing QoS specification languages along with their properties and relations.     

Toward the creation of a new medium for the multimedia era

It is expected that various new types of telecommunications services will emerge based on multimedia technologies. A concept of hypercommunication is proposed that merges human communication in cyberspace involving various people in different places, different times, and even different cultures, as well as communication with human-like agents generated by computers. Technologies necessary to realize this new telecommunications concept are described along with several research examples being done at ATR Media Integration and Communications Research Laboratories     

An EFSM-based multimedia synchronization model and the authoringsystem

Multimedia synchronization is one of the key issues to be resolved in order to have smooth multimedia presentations. The demand of bringing multimedia information systems into distributed environments makes multimedia synchronization more difficult. We apply extended finite state machines (EFSM) to formally specify multimedia synchronization among multiple media streams. Using the EFSM model, the intra-medium synchronization is handled by an actor, which is formally represented as an EFSM. The inter-media synchronization is handled by a synchronizer, which is also represented as an EFSM. Both centralized and distributed synchronization cases can be specified. The synchronizer and actors achieve the corresponding multimedia presentations cooperatively. We also propose some policies to rectify the random delays caused by networks in the distributed presentation case. These policies, which can be formally specified in the corresponding EFSMs, are classified as intra-stream and inter-stream synchronization policies. Using the EFSM-based model, an authoring system and an associated experimental execution environment has been developed on SUN SPARC workstations     

实时多媒体通信的同步模型研究

本文在对同步信息进行分类和分析的基础上,分析了ＯＣＰＮ模型的局限性,提出了改进的多媒体同步模型ＲＯＣＰＮ。通过在节点中引入媒体表现时间和同步时间,将媒体的表现与媒体间的同步行为分开,该模型解决了ＯＣＰＮ模型关于媒体内同步与媒体间同步不可兼得的问题。模拟实验表明,使用ＲＯＣＰＮ模型的多媒体流其媒体流内同步指标和媒体流间同步指标均明显优于使用ＯＣＰＮ模型的多媒体流,尤其当对象丢失率较高时,ＲＯＣＰＮ模     

Toward accommodating gender differences in multimedia communication

While there have been measurable improvements in the technical development of multimedia, research from a socio-technical viewpoint suggests that the benefits of multimedia technology, especially in fulfilling user requirements, do not always live up to initial promises. This paper aims to address one of the fundamental but often neglected areas in user requirements, i.e., gender-related issues. The paper identifies and discusses gender differences in multimedia communication and recommends how the differences can be addressed. It proposes a model for accommodating gender differences in multimedia communication.     

Converged multimedia services in emerging Web 2.0 session mobility scenarios

The increasing request for converged multimedia services have motivated relevant standardization efforts, such as the Session Initiation Protocol (SIP) to support session control, mobility, and interoperability in all-IP next generation wireless networks. Notwithstanding the central role of SIP in novel converged multimedia, the potential of SIP-based service composition for the development of new classes of Web 2.0 services able to interoperate with existing HTTP-based services is still widely unexplored. The paper proposes an original solution to improve online user experience by integrating a SIP stack into the Web browser, thus enabling the execution of novel SIP-based applications directly at the client endpoint. In particular, our browser extension coordinates with our novel SIP-based Converged Application Server to enable session mobility and prevent abuses of the services available in the client. Experimental results show that our SIP-based solution is feasible in most common Internet deployment scenarios and enables session mobility with limited management cost.     

A multimedia synchronization model and its implementation intransport protocols

An implementation of a synchronization mechanism in transport protocol to support multimedia applications over a packet or cell switched network is proposed. In designing such a mechanism for practical use, ease of implementation and capability of handling random delay of packets are two key issues for success. Since the random delay of packet or cell switched networks makes synchronization among media more complicated after the transmission across the network, a model which considers the random transmission delay is hence required to specify the temporal relationship among media. Therefore, a real-time synchronization model is presented to satisfy this requirement in the paper. Based on the proposed synchronization model, a transport protocol, namely the multimedia synchronization transport protocol (MSTP), is designed and implemented. We have implemented a prototype system using the MSTP protocol and built a simulation system for the wide area network (WAN) environment in order to evaluate the performance of the MSTP protocol