The performance of a video-on-demand server is affected by the dynamics of user accesses behavior. Most existing efforts consider static user request distributions in their design which can lead to poor performance if the accesses are different from that predicted. Even the use of a video store model to characterize user requests fails to account for the interactive nature of access. This suggests that better models for characterizing user behavior are necessary. In the recent past, the World Wide Web has become the most popular means for interactive information delivery. The World Wide Web represents a truly interactive medium with the user having complete control over presentation. Moreover, the performance bottleneck in the World Wide Web is more often the network than the server making it an ideal candidate to understand issues in serving interactive video. In this paper we study access behavior in a World Wide Web server and techniques to apply these observations in the design of a video- on-demand server.

Motion estimation is perhaps the most computationally intensive aspect of video compression. There are two major approaches to motion estimation: pel recursive and block matching. In the former approach, estimation of motion vectors is done recursively such that the motion compensated prediction error at each pel instant is minimized. In the latter approach, motion estimation is carried out on a block-by-block basis. Comparing with the pel recursive algorithms, the block matching algorithms are more realizable due to their computational simplicity. In this paper, we present a parallel algorithm using genetic search for block-based motion. The first objective of the proposed approach is to remove the need for exhaustive search by making use of genetic algorithms (GA). The second objective is to run this algorithm in parallel so that the computing time is further reduced. The algorithm is implemented using the Express library for a network of workstations and NX for the Intel Paragon.

We describe the type system component of a database management system that supports a multimedia news-on-demand application. The type system is an object-oriented one that represents document structure according to the SGML and HyTime standards. End-users access the news database by using a visual query interface. We also describe current work to generalize the database type system to accommodate arbitrary SGML/HyTime compliant multimedia documents. Such a generalized type system would support a broad range of multimedia applications.

Network-based multi-user interaction systems such as network games typically include a database shared among the players that are physically distributed and interact with one another over the network. Currently network game developers have to implement the shared database and the inter-player communications from scratch. This paper presents the architecture of a distributed system, Artery, which is specifically designed to support network game applications by providing a high-level application program interface and by taking advantage of application semantics to optimize the network performance. Artery features such network bandwidth reduction techniques as dead reckoning and message aggregation, a novel virtual world database consistency maintenance scheme based on the dynamic group consistency model, and the support for distributed dynamic environment servers. The integration of Artery's features with existing IP multicasting mechanisms is also discussed.

In this paper we discuss how classroom instruction can benefit from state-of-the-art technologies in networks, worldwide web access through Internet, multimedia, databases, and computing. Functional requirements for establishing such a high-tech classroom are identified, followed by descriptions of our current experimental implementations. The focus of the paper is on the capabilities of distributed collaboration, which supports both synchronous multimedia information sharing as well as a shared work environment for distributed teamwork and group decision making. Our ultimate goal is to achieve the concept of 'living world in a classroom' such that live and dynamic up-to-date information and material from all over the world can be integrated into classroom instruction on a real-time basis. We describe how we incorporate application developments in a geography study tool, worldwide web information retrievals, databases, and programming environments into the collaborative system.

A data model for long objects (such as video files) is introduced, to support general referencing structures, along with various system implementation strategies. Based on the data model, various indexing techniques for video are then introduced. A set of basic functionalities is described, including all the frame level control, indexing, and video clip editing. We show how the techniques can be used to automatically index video files based on closed captions with a typical video capture card, for both compressed and uncompressed video files. Applications are presented using those indexing techniques in security control and viewers' rating choice, general video search (from laser discs, CD ROMs, and regular disks), training videos, and video based user or system manuals.

Desktop conferencing systems, providing voice- or video-conferencing with some form of data sharing, have become increasingly popular. Unlike asynchronous collaborative systems such as email, little attention has been devoted to the place of agents in such real-time systems. This paper examines some of the ways in which agents can be used to support such apparently simple tasks as the setting up and answering of calls. Three agent categories, locators, routers and responders, are defined and some simple examples discussed. Several ways in which such agents can collaborate, providing the basis of an intelligent network, are identified.

Currently available video conferencing (VC) tools lack support for adaptability and session recording features. Incorporating adaptability in a system minimizes the effects of the variations in system environments on the quality of video conference sessions. Support for session recording features provides the capability of saving video sessions when the quality of service becomes unacceptable or when some of the recipients become unreachable. The latter situation arises due to network partitioning or site failures. Furthermore, recording a session is also useful when the recorded video session is expected to be replayed and retrieved by future users interested in it. In this paper, techniques for making video conferencing tools adaptable to the external environmental changes are presented. A new mechanism called video conferencing collaborator, which integrates the VC software with the video-on-demand system is introduced, and its design and implementation issues are addressed. We present the results of experiments conducted to study the potential performance improvements if the adaptability features are included in VC software. We conclude the paper with directions for our future work.

This paper describes our ongoing work on developing a multimedia data processing toolbox for the Khoros system. We first identify the functions commonly used in processing multimedia information. We then discuss how we implement these functions based on the Khoros system data structures and application programming interfaces (API). So far we have developed utilities for format conversion, editing, color conversion, etc., while the implementation of audio and video analysis algorithms is under way.

This paper provides an overview of the three language components of DAMSEL, a framework being implemented at the University of Minnesota. It is comprised of an embedable dynamic multimedia specification language, and supporting execution environments. The goal of DAMSEL is to explore language constructs and execution environments for next-generation interactive multimedia applications. DAMSEL supports dynamic, event-driven specifications for the retrieval, presentation, modification, analysis, and storage of multimedia data. Dynamic specifications enable system, application, and user-media interactions to affect the run-time behavior. The temporal language component of DAMSEL contains two primitives for event-driven temporal specification -- supporting causation and inhibition. Specifications require (extensible) behavioral parameters to be chosen, enabling very powerful temporal relations to be defined. The dataflow language component uses a dataflow paradigm, whereby data streams flow from source to sink. Sources are live devices, or storage facilities, while sinks may include simple windows, and connections to complex layouts. Modification and analysis of a data stream takes place enroute. The presentation component supports the specification of data stream connections to user interfaces. DAMSEL components support conditional and constraint logics, enabling more complex specifications than currently possible. DAMSEL also supports an open systems view, enabling current software to be used within its architecture.

A present characterized by deep worldwide changes, and a future where social relations and behaviors are going to undergo a substantial change need new telecommunications services in order to allow people to get closer, facilitate their daily tasks and place at their disposal multimedia information to be accessed anywhere and at any time. These new services are very dependent on the contents to be included in the applications. The purpose of this paper is to describe an universal MM contents production system (MM-CPS), which allows the generation of coded data files suitable to be included in MM-servers.

Every corporation is rushing to get hooked up to the Internet. Several years ago this trend started slowly with the technical folks and today forward thinking marketing types want a corporate Internet connection to push their wares on the World Wide Web. What has changed? 40,000,000 people is what's changed: the whole world, spanning 100+ countries and nation-states, is hooked together by the Internet. This Net is growing like crazy and whatever you say about it is probably already obsolete. The Net is a collection of networks where no one is in charge, no formal concrete legal or law enforcement mechanisms exist and there is little or no recourse against system abuse.

Many modern operating systems and applications focus on functionality not security. Type enforcement is a mechanism that when properly implemented in the operating system can combine high security and functionality. The paper describes how type enforcement can be used to achieve both of these important requirements. The paper also describes a specific implementation of type enforcement, the Sidewinder Internet firewall.

This paper describes the architecture of an interactive multimedia service platform in addition to implementation techniques based on the ATM transport engine under consideration. To support the interactive multimedia service, office environments need to integrate retrieval, on- demand, communicative, messaging and transactional capabilities into multi-homed hosts and heterogeneous infrastructures. Especially the various over ATM' and service provisioning mechanisms have to be considered in an evolutionary view of the platform.

The Department of Defense is both a developer and user of advanced technology. It does so, not as an end unto itself, but in support of its mission, which is to protect the national security of the country. In part, this is accomplished by 'supporting the warfighter,' and in part, by supporting the national leaders of the country. In accomplishing these ends, a careful balance must be achieved to ensure the Department has the necessary technology to successfully carry out its mission, without the imposition of 'an industrial policy.' Nor can the Department afford the creation of an artificial market, which only it will support, if alternative industrial markets will suffice.

A new focused research program in photonic data fusion networks and involving university/industry consortia is described.

This paper discusses the design phase of the development of an interactive multimedia tutorial tool for computer literacy. Research indicates interactive multimedia can be helpful to that student who does not respond to the traditional teaching methods. Can an interactive multimedia tutorial be designed to increase the success rate in computer literacy classes? The importance of the user interface is stressed and the factors to be considered in creating the user interface are discussed. How these factors were implemented in designing the interactive multimedia tutorial tool for computer literacy is presented.

Instructors of two year hydraulic technician programs encounter many students who do not understand prerequisite material. This is a prevalent concern in all fields, and multimedia software is one of the more recent developments that can be used to solve the problem. Software that centers around multimedia simulations of basic hydraulic machines while reinforcing math concepts appeals to hydraulics instructors. This paper describes multimedia software that is being developed to fulfill their need. It discusses the importance of the software as well as its structure and potential use.