. The design and implementation of a continuous media player for Unix workstations is described. The player can play synchronized digital video and audio read from a file server. The system architecture and results of preliminary performance experiments are presented. 1. Introduction Our goal is to develop a portable user interface and continuous media support library that can be used to implement a variety of multimedia applications (e.g., hypermedia systems, video conferencing, multimedia presentation systems, etc.). A key component of these applications is a continuous media (CM) player that can play scripts composed of one or more synchronized data streams. Example data streams are: digitized video or audio, animation sequences, image sequences, and text. The initial application we are implementing to test our abstractions is a video browser that allows a user to play high quality videos stored in a large database on a shared file server. Figure 1 shows a screen dump of the brows...

The design of a distributed video-on-demand system that is suitable for large video libraries is described. The system is designed to store 1000s of hours of video material on tertiary storage devices. A video that a user wants to view is loaded onto a video file server close to the users desktop from where it can be played. The system manages the distributed cache of videos on the file servers and schedules load requests to the tertiary storage devices. The system also includes a metadata database, described in a companion paper, that the user can query to locate video material of interest. This paper describes the software architecture, storage organization, application protocols for locating and loading videos, and distributed cache management algorithm used by the system.

In computer-participative multimedia applications, the computer not only manipulates media, but also digests it and performs independent actions based on media content. We present a design approach that applies the programming techniques of visualization systems to the development of computer-participative multimedia applications. We describe an implementation based on this approach, and report performance measurements that demonstrate it is practical. We conclude by describing three applications written with the system, and suggest future directions for research in the area. Keywords: programming systems, multimedia applications, digital video 1 Introduction The term multimedia generally refers to the capture, storage, retrieval and presentation of audio and video data using computers. Typical multimedia applications include online encyclopedias and video-conferencing systems. These applications are perhaps better classified as computer-mediated multimedia applications. The comput...

Video-on-Demand systems have received a good deal of attention recently. Few studies, however, have addressed the problem of locating a video of interest in a large video database. This paper describes the design and implementation of a metadata database and query interface that attempts to solve this information retrieval problem. Sample queries were collected by interviewing a variety of users. These queries guided the design of indexes that can be used to answer the types of queries users want to ask. Three types of indexes were identified: 1) bibliographic (e.g., title, abstract,

The design and performance of the Berkeley Continuous Media Toolkit (CMT) is described. CMT provides a programming environment for rapid development of continuous media applications. CMT overhead is measured in the context of a simple video playback application and is found to be only a few milliseconds per frame played. As a demonstration of CMT as a research infrastructure, an experiment comparing adaptive frame rate control policies is described.

Performance Availability for Networks of Workstations by Remzi H. Arpaci-Dusseau Software systems for large-scale distributed and parallel machines are difficult to build. When run in dynamic, production environments, not only must such systems perform correctly, but they must also operate with high performance. Much of the previous work in distributed computing has addressed the design of large-scale systems that function correctly, in spite of correctness faults of individual components [18, 49, 82, 86]. However, there has been little development of techniques to tolerate performance faults -- unexpected performance fluctuations from the components that comprise the system. Due to this shortcoming, many systems are overly sensitive to performance variations, in that global performance is high if and only if all system components perform exactly as expected. In this dissertation, we address this deficiency by formalizing the concept of performance availability. Our hypothesis is ...

In computer-participative multimedia applications, the computer not only manipulates media, but also digests it and performs independent actions based on media content. In this report I discuss an approach to the design of environments to support the development of computer-participative multimedia applications and I describe the implementation of the VuSystem, a computer-participative multimedia system built using this approach. The system is unique in that it combines the programming techniques of visualization systems and the temporal sensitivity of multimedia systems. I report measurements made of the performance of the VuSystem, which demonstrate its practicality. I conclude with a brief summary of users' experiences with the VuSystem, and suggests future directions for research in this area.

The ViewStation system embodies a software-oriented approach to the support of interactive media-based applications. Starting from the premise that the raw media data, e.g., the video pixels themselves, must eventually be made accessible to the application, we have derived a set of architectural guidelines for the design of media processing environments. The resultant ViewStation system, as described in this paper, consists of the VuSystem, a complete media programming environment, and the VuNet, a substrate for the acquisition, communication and rendering of video and closed caption text. We describe a set of computer-participative applications that demonstrate the present day viability of applications that participate in, i.e., actively process, the flow of media-based information. Early performance results illustrate the affordability and benefits of our software-oriented approach. 1.

We introduce Scriptable RPC (SRPC), an RPC-based framework that enables distributed system services to take advantage of active components. Technology trends point to a world where each component in a system (whether disk, network interface, or memory) has substantial computational capabilities; however, traditional methods of building distributed services are not designed to take advantage of these new architectures, mandating wholesale change of the software base to exploit more powerful hardware. In contrast, SRPC provides a direct and simple migration path for traditional services into the active environment. We demonstrate the power and flexibility of the SRPC framework through a series of case studies, with a focus on active storage servers. Specifically, we find three advantages to our approach. First, SRPC improves the performance of distributed file servers, reducing latency by combining the execution of operations at the file server. Second, SRPC enables the ready addition of new functionality; for example, more powerful cache consistency models can be realized on top of a server that exports a simple NFS-like interface. Third, SRPC simplifies the construction of distributed services; operations that are difficult to coordinate across client and server can now be co-executed at the server, thus avoiding costly agreement and crash-recovery protocols.

The Programmers ’ Playground is a software library and run-time system for creating distributed multimedia applications from collections of reusable software modules. This paper presents the design and implementation of EUPHORIA, Playground’s user interface management system. Implemented as a Playground module, EUPHORIA allows end-users to create direct manipulation graphical user interfaces (GUIs) exclusively through the use of a graphics editor. No programming is required. At run-time, attributes of the GUI state can be exposed and connected to external Playground modules, allowing the user to visualize and directly manipulate state information in remote Playground modules. Features of EUPHORIA include real-time direct manipulation graphics, constraint-based editing and visualization, imaginary alignment objects, user-definable types, and user-definable widgets with alternative representations.