Vod在远程教学中的应用——多媒体服务器设计＆受QOS约束的多媒体网络模型

多媒体数据与文本和数字数据有本质的不同（实时性和数据传输率），因而在存储和传输方面有很大的差异。另一方面可规划区的概念最早被引入到宽带网络Qos保证并被扩展到多媒体设备例如音视频处理和磁盘存储单元。从而引出了多媒体功能区的概念。大量的物理设备资源用以提供QOS的约束限制。建模的方法同时支持简单的逻辑对象资源连接，因此在物理实体对象的QOS之上抽象出逻辑对象的QOS。下面将主要讨论有效、可靠存储和获取多媒体资源及用以保证Qos约束的不同物理设备的多媒体功能医和可规划区。     

虚拟现实网络教学模型关键技术

随着虚拟现实技术的发展及校园网络的日益普及，结合Java和自身的特点与功能，VRML可以成为一种新的《画法几何》、《机械制图》课程多媒体课件的制作方法，利用VRML—Java技术为解决教学模型问题找到了新思路。本文研究了利用Java Applet通过VRML的外部编程接口EAI对虚拟场景中的节点对象进行精细交互控制的原理、方法和实现过程，同时对利用VRML的造型生成动画功能和实时交互技术实现构造虚拟现实网络教学模型的关键技术进行了讨论。     

A Novel Dynamic and Scalable Caching Algorithm of Proxy Server for Multimedia Objects

This paper presents a novel dynamic and scalable caching algorithm of proxy server with a finite storage size for multimedia objects. Among the multimedia such as text, image, audio and video, video is a dominant component in terms of the performance of proxy server due to its traffic characteristics. For the fast caching process, caching sequences for videos are obtained to decrease both the buffer size and the required bandwidth and saved into metafiles in advance. Then, we present a novel caching and replacing algorithms for multimedia objects based on the metafiles. Finally, experimental results are provided to show the superior performance of the proposed algorithm.     

数字化背景下的多媒体图像处理技术

图像处理技术得到较好的发展,本文以多媒体数字图像处理技术为研究对象,对其发展与应用现状进行简述,并对此技术的优缺点以及制约因素进行系统的分析,概述了此项技术在日后发展中的应用范围.通过对多媒体数字图像处理技术的分析,让我们更深入的了解此项技术,为日后的研究提供一定的理论基础.     

Early detection of children with Autism Spectrum Disorder based on visual exploration of images

Autism Spectrum Disorder is a developmental disorder characterized by a deficit in social behaviour and specific interactions such as reduced eye contact and body gestures. Recent advancements in software and hardware multimedia technologies provide the tools for early detecting the presence of this disorder. In this paper we present an approach based on the combined use of machine learning and eye tracking information. More specifically, features are extracted from image content and viewing behaviour, such as the presence of objects and fixations towards the centre of a scene. Those features are used to train a machine learning-based classifier. The obtained results show that the considered features allow to identify children affected by autism spectrum disorder and typically developing ones.     

Source localization and beamforming

Distributed sensor networks have been proposed for a wide range of applications. The main purpose of a sensor network is to monitor an area, including detecting, identifying, localizing, and tracking one or more objects of interest. These networks may be used by the military in surveillance, reconnaissance, and combat scenarios or around the perimeter of a manufacturing plant for intrusion detection. In other applications such as hearing aids and multimedia, microphone networks are capable of enhancing audio signals under noisy conditions for improved intelligibility, recognition, and cuing for camera aiming. Previous developments in integrated circuit technology have allowed the construction of low-cost miniature sensor nodes with signal processing and wireless communication capabilities. These technological advances not only open up many possibilities but also introduce challenging issues for the collaborative processing of wideband acoustic and seismic signals for source localization and beamforming in an energy-constrained distributed sensor network. The purpose of this article is to provide an overview of these issues     

Defining multimedia

Multimedia is variously and often ambiguously defined. While most people might accept a mix of voice, text and graphics, they might resist calling a live lecture on a titled work of art a multimedia presentation. On the other hand, many definitions focus entirely on technology: multimedia seems to be defined by the hardware required rather than by the user's experience. For example, despite the statement that any computer application that employs a video disk, images from a CD-ROM, uses high-quality sound, or uses high-quality video images on a screen may be termed a multimedia application, the author doubts that anyone would use the term multimedia for a computer application that merely plays a piece of music. She suggests a model of media objects that does not refer to technology or interactivity, but rather concentrates on the nature of the text. This model provides a useful basis for defining multimedia communication securely and unambiguously     

Networked multimedia: the Medusa environment

The Medusa project at Olivetti Research aims to provide a networked multimedia environment in which many streams of multimedia data, perhaps thousands, are active simultaneously. Medusa uses a peer-to-peer architecture to control networked multimedia devices. In the software model presented to the applications programmer, active objects called modules represent cameras, displays, format converters, and so on. Data flows from module to module through connections between them, with proxy modules to restrict access for security reasons. The Medusa project is based on hardware that is a collection of asynchronous transfer mode (ATM) direct peripherals, including cameras, audio systems, multimedia storage servers, LCD displays, and televisions, as well as ATM networked workstations     

Application-level differentiated multimedia Web services usingquality aware transcoding

The ability of a Web service to provide low-latency access to its content is constrained by available network bandwidth. While providing differentiated quality of service (QoS) is typically enforced through network mechanisms, in this paper we introduce a robust mechanism for managing network resources using application-specific characteristics of Web services. We use transcoding to allow Web servers to customize the size of objects constituting a Web page, and hence the bandwidth consumed by that page, by dynamically varying the size of multimedia objects on a per-client basis. We leverage our earlier work on characterizing quality versus size tradeoffs in transcoding JPEG images to supply more information for determining the quality and size of the object to transmit. We evaluate the performance benefits of incorporating this information in a series of bandwidth management policies using realistic workloads and access scenarios to drive our system. The principal contribution of this paper is the demonstration that it is possible to use informed transcoding techniques to provide differentiated service and to dynamically allocate available bandwidth among different client classes, while delivering good quality of information content for all clients. We also show that it is possible to customize multimedia objects to the highly variable network conditions experienced by mobile clients in order to provide acceptable quality and latency depending on the networks used in accessing the service. We show that policies that aggressively transcode the larger images can produce images with quality factor values that closely follow the untranscoded base case while still saving as much as 150 kB. A transcoding policy that has knowledge of the characteristics of the link to the client can avoid as many as 40% of (unnecessary) transcodings     

多媒体技术在职业院校物理学科教育中的应用

对多媒体技术在职业院校物理学科教育中的应用进行了研究和探讨,在简要分析多媒体技术的应用价值基础上,重点分析了存在的问题,最后就职业院校物理学科教育中科学、有效、全面、系统应用多媒体技术提出优化对策,旨在为促进职业院校物理学科教育实现更大突破提供参考与借鉴。     

多媒体数据库管理系统

多媒体数据库管理系统是针对多媒体数据的有效管理而提出的一个数据库管理系统,跟一些传统的数据库管理系统相比,多媒体数据不同于传统数据,是一种非格式化数据,具有对象复杂、存储分散及时空同步等特点。为方便管理,本系统采用面向对象方法进行设计与开发。通过引入封装、继承、对象和类等概念,可以有效地描述各种对象及其内部结构与联系,提高对非格式化多媒体数据的管理能力。     

ATM to the desktop: Impacting modern business communications with broadband technology

Asynchronous transfer mode (ATM) technology is being touted as a “silver bullet” solution that will enable a host of new and advanced multimedia services seamlessly across both local and wide area networks. While it appears likely that ATM will have a genuine impact on the future of business communications, a major hurdle that needs to be overcome before this happens lies with the semantic gap that exists between the ATM technology development and marketing community and the prospective customer base which stands to benefit from the technology. The work described in this paper represents our attempt to help close this gap through an examination of the kinds of multimedia business applications we believe ATM technology will provide its end users. We describe sample demonstration applications developed at GTE Laboratories that help to explain how ATM can impact business communications from the desktop. A further theme of the work described concerns our efforts to take best advantage of key features of ATM to assist ongoing investigation of multimedia application concepts and their implementation.     

Segmentation of moving objects in image sequence: A review

Segmentation of objects in image sequences is very important in many aspects of multimedia applications. In second-generation image/video coding, images are segmented into objects to achieve efficient compression by coding the contour and texture separately. As the purpose is to achieve high compression performance, the objects segmented may not be semantically meaningful to human observers. The more recent applications, such as content-based image/video retrieval and image/video composition, require that the segmented objects be semantically meaningful. Indeed, the recent multimedia standard MPEG-4 specifies that a video is composed of meaningful video objects. Although many segmentation techniques have been proposed in the literature, fully automatic segmentation tools for general applications are currently not achievable. This paper provides a review of this important and challenging area of segmentation of moving objects. We describe common approaches including temporal segmentation, spatial segmentation, and the combination of temporal-spatial segmentation. As an example, a complete segmentation scheme, which is an informative part of MPEG-4, is summarized.     

VPN技术在高校媒体资产管理系统中的应用分析

高校媒体资产管理系统是以高校多媒体资料为管理对象,面向全校师生服务,网络范围覆盖整个校园网的校园多媒体网络管理系统,为了解决师生在校外,可以远程使用校园多媒体资源,针对远程接入中的SSL和IPSEC两种VPN技术进行比较分析,以探讨一种适合高校多媒体数据传输的VPN接入模式。     

Temporal relations and synchronization agents

Temporal relationships, inevitable among distributed multimedia objects, require synchronization of multiple data streams in time. We propose using synchronization agents as “smart” distributed objects to deal with scheduling, integrating, and synchronizing distributed multimedia streams. A formal specification model, interoperable Petri nets, describes the agents' behavior and captures the temporal semantics existing among distributed multimedia objects     

Timed Petri net representation of SMIL

A multimedia server needs to satisfy the temporal relations between multimedia objects when servicing clients. We propose an enhanced timed Petri net (TPN) model to capture the information of multimedia objects along with their timing and synchronization specified in the synchronized multimedia integration language (SMIL) of XML.     

Multimedia is the message

Multimedia, as an application, has at its very core the field of signal processing technology. In this article, an attempt is made to provide a historical overview of signal processing through the present, followed by a highly personal speculation for the future. As important as the multimedia technology is today, its further dramatic growth is predictable. Technological constraints, such as communication bandwidth, processing components, availability of open standards, and display technologies are being successfully addressed by industry. Signal processing technologies have made important contributions to all areas of multimedia and will continue to do so. Signal processing has been particularly important in all areas of compression, modeling, and the entire field of digital representation of complex signals     

Reconstructing a thule whalebone house using 3D imaging

In this article, the authors share with us an interesting use for the latest laser-scanning-based 3D imaging technology for reconstructing a thule whalebone house. All major components (such as date capturing, data modeling, display, and interaction) are covered to demonstrate how archaeological research can benefit from this new technology for the purposes of testing and education. Although this article focuses on building the skeletal models of a whale, it also provides a stepping-stone to the researchers, engineers, architects, and archaeologists who are interested in virtual reality. Interactive digital media is becoming one of the hot areas in the multimedia community, which aims to provide users with an immersive experience while consuming media.