Disk placement for arbitrary-rate playback in an interactive video server

Multimedia data, especially continuous media including video and audio objects, represent a rich and natural stimulus for humans, but require large amount of storage capacity and real-time processing. In this paper, we describe how to organize video data efficiently on multiple disks in order to support arbitrary-rate playback requested by different users independently. Our approach is to segment and decluster video objects and to place the segments in multiple disks using a restricted round-robin scheme, called prime round-robin (PRR). Its placement scheme provides uniform load balance of disks for arbitrary retrieval rate as well as normal playback, since it eliminates hot spots. Moreover, it does not require any additional disk bandwidth to support VCR-like operations such as fast-forward and rewind. We have studied the various effects of placement and retrieval schemes in a storage server by simulation. The results show that PRR offers even disk accesses, and the failure in reading segment by deadline occurs only at the beginning of new operations. In addition, the number of users admitted is not decreased, regardless of arbitrary-rate playback requests.     

多媒体会议系统研究

多媒体会议系统是一种典型实用的计算机支持的协同工作（ＣＳＣＷ）应用，最近几年发展很快，受到了广泛的重视。我们从多媒体技术和计算机网络技术两方面出发对多媒体会议系统进行系统研究，在此基础上，提出多媒体会议系统的总体设计，特别是针对多媒体会议系统的关键问题和支持多媒体网络协议存在的问题，提出了多媒体通信服务模型，以试衅弥补当前网络协议对服务质量（ＱＯＳ）的不足，同时也给出了新服务模型下的参考实现框架。     

On periodic resource scheduling for continuous-media databases

The Enhanced Pay-Per-View (EPPV) model for providing continuous-media services associates with each continuous-media clip a display frequency that depends on the clip's popularity. The aim is to increase the number of clients that can be serviced concurrently beyond the capacity limitations of available resources, while guaranteeing a constraint on the response time. This is achieved by sharing periodic continuous-media streams among multiple clients. The EPPV model offers a number of advantages over other data-sharing schemes (e.g., batching), which make it more attractive to large-scale service providers. In this paper, we provide a comprehensive study of the resource-scheduling problems associated with supporting EPPV for continuous-media clips with (possibly) different display rates, frequencies, and lengths. Our main objective is to maximize the amount of disk bandwidth that is effectively scheduled under the given data layout and storage constraints. Our formulation gives rise to -hard combinatorial optimization problems that fall within the realm of hard real-time scheduling theory. Given the intractability of the problems, we propose novel heuristic solutions with polynomial-time complexity. We also present preliminary experimental results for the average case behavior of the proposed scheduling schemes and examine how they compare to each other under different workloads. A major contribution of our work is the introduction of a robust scheduling framework that, we believe, can provide solutions for a variety of realistic EPPV resource-scheduling scenarios, as well as any scheduling problem involving regular, periodic use of a shared resource. Based on this framework, we propose various interesting research directions for extending the results presented in this paper. Received June 9, 1998 / Accepted October 13, 1998     

The multimedia multicasting problem

This paper explores the problems associated with the multicasting of continuous media to support multimedia group applications. The interaction between multicasting and the delivery of multiple time-correlated continuous-media streams with real-time delay requirements poses various new and interesting problems in research on communication protocols and architectures. We describe these problems, and identify where the opportunities are for effective solutions, all in the context of providing an overview of the current state of research in multimedia multicasting. The issues we discuss include quality of service, resource reservations, routing, error and traffic control, heterogeneity, and the use of hierarchical coding and open-loop control techniques.     

MING-I: a distributed interactive multimedia document development mechanism

The next generation of interactive multimedia documents can contain both static media, e.g., text, graph, image, and continuous media, e.g., audio and video, and can provide user interactions in distributed environments. However, the temporal information of multimedia documents cannot be described using traditional document structures, e.g., Open Document Architecture (ODA) and Standard Generalized Mark-up Language (SGML); the continuous transmission of media units also raises some new synchronization problems, which have not been met before, for processing user interactions. Thus, developing a distributed interactive multimedia document system should resolve the issues of document model, presentation control architecture, and control scheme. In this paper, we (i) propose a new multimedia document model that contains the logical structure, the layout structure, and the temporal structure to formally describe multimedia documents, and (ii) point out main interaction-based synchronization problems, and propose a control architecture and a token-based control scheme to solve these interaction-based synchronization problems. Based on the proposed document model, control architecture, and control scheme, a distributed interactive multimedia document development mechanism, which is called MING-I, is developed on SUN workstations.     

XOCPN：支持用户交互的多媒体同步模型

多媒体同步是多媒体应用的一个重要需求。本文对ＯＣＰＮ模型进行了扩展，提出了一种基于时间Ｐｅｔｒｉ网的多媒体同步模型ＸＯＣＰＮ，以对具有时间约束关系的多媒体合成进行规范描述，并具有支持灵活用户交互的能力。文中给出了处理异步用户交互的算法，并用示例说明。     

一个基于多媒体X终端的协作CAD系统

本文提出了一种基于多媒体Ｘ终端的协作ＣＡＤ体系结构，它充分利用了Ｘ终端的网络透明性，将核心计算和用户间通讯的模块集中到高性能的主机上，从而提高了协作ＣＡＤ系统的性能。系统还提供了虚拟声音会议环境使得用户间可以直接地通过语音交互。     

异地计算机教学与训练系统的结构模型研究

异地计算机教学与训练系统就是利用计算机网络环境，向分布在异地的授课者和学习者提供一种模拟面对面教学和训练的虚拟环境。     

利用VisualBasic5.0实现多媒体演示

本文介绍利用Visual Basic 5.0进行多媒体程序设计的方法,并给出一个可以用于产品演示的多媒体程序     

丰富多采的VB下的动画播放

动画设计与播放是多媒体技术的具体应用，是应用软件开发的热门领域。ＶＢ中也有关于动画播放的功能，本文介绍一种较为简单直接的实现方法，经调试应用效果较好。