MPEG-7描述多媒体内容的方法

随着多煤体技术和Web技术的发展，出现了大量的多煤体数据。为了更好地管理和检索多煤体数据，我们需要一种描述多煤体内容的标准。本文首先分析了MPEG-7标准多煤体内容的据述工具，然后从结构和内容两个方面提出了MPEG-7描述多煤体内容的方法。最后，我们还讨论了一些与MPEG-7描述相关的研究问题。     

Visual content adaptation according to user perception characteristics

Adapting multimedia content to users' preferences and perceptual characteristics is a key direction for enabling personalized multimedia services. In this paper, we address the problem of tailoring visual content within the MPEG-21 Digital Item Adaptation (DIA) framework to meet users' visual perception characteristics. In particular, we present methods for adapting visual content to accommodate color vision deficiency and low-vision capabilities. In addition, we present methods for adapting visual content according to user preferences for color temperature. Finally, we report on experiments that adapt visual content within the MPEG-21 DIA framework.     

内容适配技术研究综述

内容适配技术是实现通用多媒体接入的技术体系。MPEG-21标准提出了内容适配技术框架和服务环境描述技术规范。针对MPEG-21内容适配框架,从内容适配系统、服务环境数据交换、适配决策等方面,介绍国内外相关研究现状。     

基于MPEG-7标准的视频描述

随着多媒体技术和Web技术的发展，出现了大量的多媒体数据。为了更好地管理和检索多媒体数据，我们需要一种描述多媒体内容的标准。本文根据标准化的描述框架-MPEG- 7，提出了视频对象特征提取与检索系统中的描述原型，主要包括MPEG-7标准的内容描述和视觉描述。最后，讨论了一些与视频描述相关的问题。     

Digital item adaptation: overview of standardization and research activities

MPEG-21 Digital Item Adaptation (DIA) has recently been finalized as part of the MPEG-21 Multimedia Framework. DIA specifies metadata for assisting the adaptation of Digital Items according to constraints on the storage, transmission and consumption, thereby enabling various types of quality of service management. This paper provides an overview of DIA, describes its use in multimedia applications, and reports on some of the ongoing activities in MPEG on extending DIA for use in rights governed environments.     

用MPEG-7 DDL表示用户查询需求的方法

随着ISO MPEG-7标准在多媒体信息检索领域的深入应用,如何描述用户的查询信息需求变得越来越重要,本文提出一种新的用户查询需求的表示方法。该方法的主要特点是充分考虑MPEG-7标准对多媒体内容的标准化描述特性,因此对用户提交的信息需求具有很强的表达能力和较好的通用性。     

一种利用继承关系的业务服务实例化方法

随着面向服务计算技术的日渐普及,通过互联网提供的科研领域的Web服务也越来越多,目前仅在生物信息领域可统计到的Web服务数量就超过3000个.然而,怎样在业务层上将最终用户的个性化需求快速实例化到具体的Web服务,成为很多专业工作者关心的问题,生物信息领域尤其突出.为了解决这个问题,提出一种利用继承关系的业务服务实例化方法,该方法基于我们前期工作中提出的抽象服务形式--业务服务,通过对基类业务服务的继承操作构建表达最终用户个性化需求的子类业务服务,同时建立了两个业务服务之间的继承关系,并且利用这种继承关系将最终用户的个性化需求快速实例化到具体的Web服务.     

Optimal adaptation decision-taking for terminal and network quality-of-service

In order to cater to the diversity of terminals and networks, efficient, and flexible adaptation of multimedia content in the delivery path to end consumers is required. To this end, it is necessary to associate the content with metadata that provides the relationship between feasible adaptation choices and various media characteristics obtained as a function of these choices. Furthermore, adaptation is driven by specification of terminal, network, user preference or rights based constraints on media characteristics that are to be satisfied by the adaptation process. Using the metadata and the constraint specification, an adaptation engine can take an appropriate decision for adaptation, efficiently and flexibly. MPEG-21 Part 7 entitled Digital Item Adaptation standardizes among other things the metadata and constraint specifications that act as interfaces to the decision-taking component of an adaptation engine. This paper presents the concepts behind these tools in the standard, shows universal methods based on pattern search to process the information in the tools to make decisions, and presents some adaptation use cases where these tools can be used.     

基于感知运动能量模型的MPEG-21数字项适配

最新的MPEG-21标准定义了一个统一的多媒体框架,其目标是使多媒体资源能在异构网络和终端上进行透明传输和得到充分利用。多媒体适配(Multimedia Adaptation)技术作为实现上述目标的关键技术得到了越来越多的研究。本文将感知运动能量模型与MPEG-21数字项适配框架相结合,研究和实现了基于感知运动能量的H．264／AVC视频丢帧适配技术。本文的研完工作有两个方面的优点：一方面,感知运动能量模型的使用将丢帧适配引起的运动抖动减至最小,保证了较高的用户视觉上的主观感知质量;另一方面,数据处理能力和资源受限的适配节点不需了解具体的H．264／AVC编码语法结构和编解码算法,就能方便地执行丢帧操作,实现了独立于媒体编码格式的视频适配机制,提高了多媒体适配系统的灵活性和可扩展性。     

面向MPEG-21 DIA的适配决策模型

通用多媒体内容访问是未来多媒体服务的常用模式。针对这一访问模式,MPEG-21提出了DIA技术框架,以期实现相关技术标准化。但是,DIA现在只对上下文描述等元数据制定了标准,而适配决策引擎仍然是一个开放问题。针对已有适配决策模型存在的问题,提出了一种适配决策树模型,该模型将适配决策视为序列决策,并用决策树对其建模。为满足多媒体服务的个性化需求,利用用户偏好信息建立适配决策树。此外,利用优化模型构建决策空间,使参与决策的对象数缩小为模态数,从而减少了适配决策时间,满足了多媒体服务的实时性。通过仿真实验证明,该适配决策树模型在决策误差和平均迭代次数两个指标上都优于或相近于已有的适配决策模型。     

Adapting multimedia Internet content for universal access

Content delivery over the Internet needs to address both the multimedia nature of the content and the capabilities of the diverse client platforms the content is being delivered to. We present a system that adapts multimedia Web documents to optimally match the capabilities of the client device requesting it. This system has two key components. 1) A representation scheme called the InfoPyramid that provides a multimodal, multiresolution representation hierarchy for multimedia. 2) A customizer that selects the best content representation to meet the client capabilities while delivering the most value. We model the selection process as a resource allocation problem in a generalized rate distortion framework. In this framework, we address the issue of both multiple media types in a Web document and multiple resource types at the client. We extend this framework to allow prioritization on the content items in a Web document. We illustrate our content adaptation technique with a web server that adapts multimedia news stories to clients as diverse as workstations, PDA's and cellular phones     

基于Web Service的多层音频分类器设计

随着网络技术的发展和多媒体数据的增长,应用对音频内容的分类、查询、检索需求越来越强烈。MPEG-7和MPEG-21等标准的出现为多媒体内容的规范化提供了良好的外部条件,有利于进一步向基于内容检索服务的过渡。介绍了一个基于Web服务分布式部署的多层音频分类器的设计,提出以特征代理为前端进行特征提取,分类代理为后端进行特征处理,节点采用多分类器融合策略,通过发布/订阅机制实现音频特征的传送。系统结构有利于进一步扩展,从而为音频内容查询检索和音频搜索引擎等应用提供平台式服务。     

Optimum adaptation trajectories for streamed multimedia

Most adaptive delivery mechanisms for streaming multimedia content do not explicitly consider user-perceived quality when making adaptations. We propose that an optimal adaptation trajectory through the set of possible encodings exists and that it indicates how to adapt encoding quality in response to changes in network conditions to maximize user-perceived quality. Such an optimum adaptation trajectory can be used with any transmission adaptation policy. We describe the subjective tests we carried out to find such trajectories for a number of different MPEG-4 video clips and indicate how this knowledge could be used in the operation of a practical system.     

Integrating implicit feedbacks for time-aware web service recommendations

An increasing number of Web services have been published on the Internet over the past decade due to the rapid development and adoption of the SOA (Services Oriented Architecture) standard. However, in the current state of the Web, recommending suitable Web services to users becomes a challenge due to the huge divergence in published content. Existing Web services recommendation approaches based on collaborative filtering are mainly aiming to QoS (Quality of Service) prediction. Recommending services based on users’ ratings on services are seldomly reported due to the difficulty of collecting such explicit feedback. In this paper, we report a data set of implicit feedback on real-world Web services, which consist of more than 280,000 user-service interaction records, 65,000 service users and 15,000 Web services or mashups. Temporal information is becoming an increasingly important factor in service recommendation since time effects may influence users’ preferences on services to a large extent. Based on the collected data set, we propose a time-aware service recommendation approach. Temporal information is sufficiently considered in our approach, where three time effects are analyzed and modeled including user bias shifting, Web service bias shifting, and user preference shifting. Experimental results show that the proposed approach outperforms seven existing collaborative filtering approaches on the prediction accuracy.     

Web服务的Pi演算描述

如何从已有的 Web 服务构造新的增值性的正确的 Web 服务,已成为研究 Web 服务的群体关注的一个焦点。因此,为了得到可靠的、高质量的服务,必须找到一种建模方法和工具,在 Web 服务投入使用之前,对其进行分析和验证。本文主要从过程代数的角度出发,用 Pi 演算来描述 Web 服务以及 Web 服务的组合。