Efficient Query Execution Techniques in a 4DIS Video Database System for eLearning

In this paper, we describe our work on developing an eLearning video database system. The eLearning video database provides a temporal modeling framework for describing eLearning video data and it supports data distribution by applying vertical class partitioning techniques. Building on top of our previous work on Four Dimensional Information System (4DIS)—an object-oriented temporal modeling framework, we apply vertical class partitioning techniques onto a 4DIS eLearning video database system as a means for efficient query execution. We further describe our work on dynamic fetching of multimedia eLearning video on the Internet. A detailed cost model for query execution through vertical class partitioning is developed. Finally, we demonstrate through the use of a running example the effectiveness of our vertical class partitioning approach.     

分布式多媒体系统中的媒体同步

本文介绍分布式多媒体系统中的媒体同步问题，着重介绍了基于MPEG－I的分布式多媒体系统中，视频和音频的同步以及媒体服务器和客户之间的流同步。     

Disk scheduling in video editing systems

Modern video servers support both video-on-demand and nonlinear editing applications. Video-on-demand servers enable the user to view video clips or movies from a video database, while nonlinear editing systems enable the user to manipulate the content of the video database. Applications such as video and news editing systems require that the underlying storage server be able to concurrently record live broadcast information, modify prerecorded data, and broadcast an authored presentation. A multimedia storage server that efficiently supports such a diverse group of activities constitutes the focus of this study. A novel real-time disk scheduling algorithm is presented that treats both read and write requests in a homogeneous manner in order to ensure that their deadlines are met. Due to real-time demands of movie viewing, read requests have to be fulfilled within certain deadlines; otherwise, they are considered lost. Since the data to be written into disk is stored in main memory buffers, write requests can be postponed until critical read requests are processed. However, write requests still have to be processed within reasonable delays and without the possibility of indefinite postponement. This is due to the physical constraint of the limited size of the main memory write buffers. The new algorithm schedules both read and write requests appropriately, to minimize the amount of disk reads that do not meet their presentation deadlines, and to avoid indefinite postponement and large buffer sizes in the case of disk writes. Simulation results demonstrate that the proposed algorithm offers low violations of read deadlines, reduces waiting time for lower priority disk requests, and improves the throughput of the storage server by enhancing the utilization of available disk bandwidth     

I-Media: An integrated Media server and Media database as a basic component of a cross Media publishing system

The publication of the same information on different media, the so-called Cross Media Publishing (CMP), is becoming one of the central aspects in today's publishing industry. CMP centers on a media independent document definition and an efficient integrated publishing on different media: e.g. as a paper document, as an online document in the World Wide Web, and as an offline (CD-ROM based) multimedia presentation. The aim of CMP is to get these different media at the same stage, while—and that is important—spending an acceptable amount of additional effort (in time and money) for production. In this paper we present a solution for a key problem of Cross Media Publishing, the handling of media data (images, audio, video, etc.) by using a combined approach of server and database systems functionality. The integrated multimedia server and database i-Media and its role in a complete CMP solution will be presented.     

Rama: An architecture for Internet information filtering

This paper describes Rama, a first generation experimental information retrieval and filtering system that attempts to recover useful information from various Internet sources including USENIX news and anonymous FTP servers. The focus of the Rama system to date has been on building a distributed query and information retrieval system, which provides an interface to heterogeneous information services. A user of Rama sends one or more asynchronous queries to a Rama server using existing SMTP e-mail clients. The server periodically searches local and remote Internet services. Searches are prefiltered with the use of timestamps. Data objects which are newer than the timestamp are then searched via a query mechanism which relies on a combination of vector-distance, pattern matching operands, and boolean operators. Results are weighted according to how closely they match queries and are posted via e-mail to the user. Input to the e-mail client can be further filtered — one can use the MH mail system and sort input by weight. Results indicate that the current system is useful and extensible. So far we have assumed that existing e-mail systems will be used for input and output and have not attempted to construct special client interfaces. Efforts are underway to extend the system with WWW searching capabilities and construct a special WWW oriented user-interface.     

An object-oriented multimedia database system for a news-on-demand application

We describe the design of a multimedia database management system for a distributed news-on-demand multimedia information system. News-on-demand is an application that uses broadband network services to deliver news articles to subscribers in the form of multimedia documents. Different news providers insert articles into the database, which are then accessed by users remotely, over a broadband, asynchronous transfer-mode (ATM) network. The particulars of our design are an object-oriented approach and strict adherence to international standards, in particular the Standard Generalized Mark-up Language (SGML) and Hy-Time. The multimedia database system has a visual query facility, which is also described in this paper. The visual query interface provides three major facilities for end users: presentation, navigation, and querying of multimedia news documents. The main focus, however, is the querying of multimedia objects stored in the database.     

Load sharing in distributed multimedia-on-demand systems

Service providers have begun to offer multimedia-on-demand services to residential estates by installing isolated, small-scale multimedia servers at individual estates. Such an arrangement allows the service providers to operate without relying on a highspeed, large-capacity metropolitan area network, which is still not available in many countries. Unfortunately, installing isolated servers can incur very high server costs, as each server requires spare bandwidth to cope with fluctuations in user demand. The authors explore the feasibility of linking up several small multimedia servers to a (limited-capacity) network, and allowing servers with idle retrieval bandwidth to help out servers that are temporarily overloaded; the goal is to minimize the waiting time for service to begin. We identify four characteristics of load sharing in a distributed multimedia system that differentiate it from load balancing in a conventional distributed system. We then introduce a GWQ load sharing algorithm that fits and exploits these characteristics; it puts all servers' pending requests in a global queue, from which a server with idle capacity obtains additional jobs. The performance of the algorithm is captured by an analytical model, which we validate through simulations. Both the analytical and simulation models show that the algorithm vastly reduces wait times at the servers. The analytical model also provides guidelines for capacity planning. Finally, we propose an enhanced GWQ+L algorithm that allows a server to reclaim active local requests that are being serviced remotely. Simulation experiments indicate that the scheduling decisions of GWQ+L are optimal, i.e., it enables the distributed servers to approximate the performance of a large centralized server     

新闻视频的场景分段索引及摘要生成

在提出一种新闻视频检索系统结构的基础上，介绍了基于标题条检测的新闻场景分段索引方法，并阐述了两种新闻摘要的生成策略．该方法利用新闻节目标题条出现的时空位置线索，结合标题关键词的识别，建立起一个层次化的新闻视频索引结构，并帮助用户通过新闻摘要实现不同要求的视频浏览．实验证明该方法有较高的检索成功率，并且简单快捷，为新闻视频检索提供了新的有效途径．     

Scheduling and data layout policies for a near-line multimedia storage architecture

Recent advances in computer technologies have made it feasible to provide multimedia services, such as news distribution and entertainment, via high-bandwidth networks. The storage and retrieval of large multimedia objects (e.g., video) becomes a major design issue of the multimedia information system. While most other works on multimedia storage servers assume an on-line disk storage system, we consider a two-tier storage architecture with a robotic tape library as the vast near-line storage and an on-line disk system as the front-line storage. Magnetic tapes are cheaper, more robust, and have a larger capacity; hence, they are more cost effective for large scale storage systems (e.g., video-on-demand (VOD) systems may store tens of thousands of videos). We study in detail the design issues of the tape subsystem and propose some novel tape-scheduling algorithms which give faster response and require less disk buffer space. We also study the disk-striping policy and the data layout on the tape cartridge in order to fully utilize the throughput of the robotic tape system and to minimize the on-line disk storage space.     

电子新闻管理系统的研究

本文简要介绍和分析电子新闻系统的工作原理和电子新闻服务器的系统结构,阐述了电子新闻管理系统在电子新闻服务器中的地位和作用,提出电子新闻管理系统的目标及管理活动,给出一个新闻管理系统的详细设计方案。     

Instantly indexed multimedia databases of real world events

We introduce a new paradigm for real-time conversion of a real world event into a rich multimedia database by processing data from multiple sensors observing the event. A real-time analysis of the sensor data, tightly coupled with domain knowledge, results in instant indexing of multimedia data at capture time. This yields semantic information to answer complex queries about the content and the ability to extract portions of data that correspond to complex actions performed in the real world. The power of such an instantly indexed multimedia database system, in content-based retrieval of multimedia data or in semantic analysis and visualization of the data, far exceeds that of systems which index multimedia data only after it is produced. We present LucentVision, an instantly indexed multimedia database system developed for the sport of tennis. This system analyzes video from multiple cameras in real time and captures the activity of the players and the ball in the form of motion trajectories. The system stores these trajectories in a database along with video, 3D models of the environment, scores, and other domain-specific information. LucentVision has been used to enhance live television and Internet broadcasts with game analyses and virtual replays in more than 250 international tennis matches.     

Personalcasting: Tailored Broadcast News

Broadcast news sources and newspapers provide society with the vast majority of real-time information. Unfortunately, cost efficiencies and real-time pressures demand that producers, editors, and writers select and organize content for stereotypical audiences. In this article we illustrate how content understanding, user modeling, and tailored presentation generation promise personalcasts on demand. Specifically, we report on the design and implementation of a personalized version of a broadcast news understanding system, MITRE’s Broadcast News Navigator (BNN), that tracks and infers user content interests and media preferences. We report on the incorporation of Local Context Analysis to both expand the user’s original query to the most related terms in the corpus, as well as to allow the user to provide interactive feedback to enhance the relevance of selected newsstories. We describe an empirical study of the search for stories on ten topics from a video corpus. By personalizing both the selection of stories and the form in which they are delivered, we provide users with tailored broadcast news. This individual news personalization provides more fine-grained content tailoring than current personalized television program level recommenders and does not rely on externally provided program metadata.     

基于领域本体的新闻视频检索

新闻视频作为视频数据中有代表性的一种媒体,受到人们的广泛关注,对新闻视频的检索要求也越来越高.传统的新闻视频检索大多是非语义层面的,采用的是基于关键词的检索方法，难于获得令人满意的查准率和查全率．本文提出一种基于领域本体的新闻视频检索框架，定义了新闻视频检索中的新闻视频对象，使用语义表达能力强的领域本体来指导视频语义对象的标注，并针对“一词多义”问题提出了“概念域-概念”两阶段概念消歧算法；针对自然语言检索问题，使用领域本体进行查询优化和查询扩展，并提出了查询语句自动生成方法．实验表明，基于领域本体的新闻视频检索方法可以有效的提高检索性能．     

Design and implementation of a video browsing system for the Internet

Recent advances in multimedia processing technologies, internet‐working technologies, and the World Wide Web phenomenon have resulted in a vast creation and use of digital videos. Due to this reason, an efficient technique to locate and retrieve a desired video from a remote video archive is needed. A trial‐and‐error approach popularly used in current Web search engines is not applicable for searching for a desired video segment since the technique incurs intolerable delays. In this paper, we present the design and implementation of a video browsing system that lets the user view a summary of a selected video and search within the video while being downloaded so that the user can determine the relevance of the video as early as possible. The system is inexpensive and scalable, making it suitable for large‐scale distributed systems such as the Internet. The browsing system consists of two major software components: a video server, and a video browser and player called VideoCenter implemented using Microsoft DirectShow multimedia development kit. The implementation of VideoCenter enables us to assess the ease of use of DirectShow as well as its drawbacks in developing multimedia applications. Copyright © 2001 John Wiley & Sons, Ltd.     

Automatic Segmentation of News Items Based on Video and Audio Features

The automatic segmentation of news items is a key for implementing the automatic cataloging system of news video.This paper presents an approach which manages audio and video feature infomation to automatically segment news items.The integration of audio and visual analyses can overcome the weakness of the approach using only image analysis techniques.It makes the approach more adaptable to various situations of news items.The proposed approach detects silence segments in accompanying audio,and integrates them with shot segmentation results,as ewll as anchor shot detection results,to determine the boundaries among news items,Expeimental results show that the integration of audio and video features is an effective approach to solving the problem of automatic segmentation of news items.     

Odyssey: a high‐performance clustered video server

Video servers are essential in video‐on‐demand and other multimedia applications. In this paper, we present our high‐performance clustered CBR video server, Odyssey. Odyssey is a server connecting PCs with switched Ethernet. It provides efficient support for normal play and interactive browsing functions such as fast‐forward and fast‐backward. We designed a set of algorithms for scheduling, synchronization and admission control, which results in a high utilization of resources. Odyssey is able to deliver a large number of video streams. Copyright © 2003 John Wiley & Sons, Ltd.     

基于语义人脸的视频新闻标注

视频和图像中的人脸蕴涵了丰富的语义信息，可以使用人脸对视频内容进行分析与标注，尤其是视频新闻节日。而要达到这样的目的，就必须先将对视频新闻具有语义价值的人脸从视频流中检测出来。本文提出基于语义人脸捡测的视频新闻语义聚类与标注算法：在这个算法中，首先使用肤色模型检测人脸可能出现区域，然后提取人脸可能区域的独立成分特征，用训练好的支持向量机检测出所有人脸，套用语义人脸模板过滤出最终的语义人脸集合，最后通过高斯混合聚类，将视频新闻标注为主持人镜头、访谈类新闻镜头和其他新闻故事镜头三类。实验表明，该算法在视频新闻结构化中可以得到较好的应用。