Delivering audiovisual content with MPEG-21-enabled cross-layer QoS adaptation

Future multimedia communication systems have to support the user‘s needs, the terminal capabilities, the content specification and the underlying networking technologies. The related protocols and applications must be designed from this integration perspective in a cross-layer centric manner. In this paper, we propose an implementation of a streaming service (e.g.,Television over IP service) with a unified QoS management concept that enables an IP driven integration of different system components (terminal, user, content, and network). The MPEG-21 framework is used to provide a common support for implementing and managing the end-to-end QoS. The main focus of this paper is on the architecture design, protocols specification and implementation evaluation. Performance evaluations using PSNR and SSIM objective video quality metrics show the benefit of the proposed MPEG-21-enabled cross-layer adaptation.     

Protection of mobile location privacy by using blind signature

INTRODUCTION Improvements in sensor and wireless commu-nication technology enable accurate, automated de-termination and dissemination of a user or object’sposition. There is great interest in exploiting thispositional data through location-based services (LBS)Because of the widespread use of relatively cheapcellular phones or other mobile devices, many loca-tion services will be based on tracking technology toreveal the mobile user’s “personal” location at anygiven time (Einar, 200…     

SVC bitstream adaptation in MPEG-21 multimedia framework

INTRODUCTION Scalable video coding (SVC) (Schwarz et al., 2004) is the most promising video format for appli- cations of collaborative communication. First, SVC format, which is extended from the latest advanced video coding (AVC), is appropriate for creating a wide variety of bitrates with high compression effi- ciency. Second, an original SVC bitstream can be easily truncated in different ways to meet various characteristics and variations of devices and connec- tions. The scalabil…     

3G技术在新闻直播中的运用

随着第三代数字无线移动通信网络以及多媒体信息服务的迅猛发展,3G视频通信的高可用性已成为业界关注的一个新的焦点。本文着重论述将3G视频技术应用于新闻直播的可行性,描述3G视频直播系统的构建和技术特征．探讨不同制式下的3G运营网络对3G视频直播设备使用的影响和技术应对措施。     

WCDMA关键技术的研究简

WCDMA技术的设计目标是不仅能够提供比第二代移动通信系统更大的容量和更好的通信质量．而且要能在全球范围内更好地实现无缝漫游并为用户提供语音、数据和移动多媒体等业务。与第二代移动通信相比,WCDMA系统采用直扩序列码分多址技术（DS—CDMA）,信息被扩展成3．84Mchip／s后在5MHz带宽内传送,同时采角了多种关键技术保证业务质量（QoS）。概括来说,WCDMA关键技术主要包括RAKE接收技术、无线资源管理技术、多用户检测技术和智能天线技术等。     

Investigation of High School Students’ Online Science Information Searching Performance: The Role of Implicit and Explicit Strategies

Due to a growing trend of exploring scientific knowledge on the Web, a number of studies have been conducted to highlight examination of students’ online searching strategies. The investigation of online searching generally employs methods including a survey, interview, screen-capturing, or transactional logs. The present study firstly intended to utilize a survey, the Online Information Searching Strategies Inventory (OISSI), to examine users’ searching strategies in terms of control, orientation, trial and error, problem solving, purposeful thinking, selecting main ideas, and evaluation, which is defined as implicit strategies. Second, this study conducted screen-capturing to investigate the students’ searching behaviors regarding the number of keywords, the quantity and depth of Web page exploration, and time attributes, which is defined as explicit strategies. Ultimately, this study explored the role that these two types of strategies played in predicting the students’ online science information searching outcomes. A total of 103 Grade 10 students were recruited from a high school in northern Taiwan. Through Pearson correlation and multiple regression analyses, the results showed that the students’ explicit strategies, particularly the time attributes proposed in the present study, were more successful than their implicit strategies in predicting their outcomes of searching science information. The participants who spent more time on detailed reading (explicit strategies) and had better skills of evaluating Web information (implicit strategies) tended to have superior searching performance.     

Unequal Forced-Intra-Refresh for robust video streaming

INTRODUCTION In the encoding or transcoding of video stream- ing, intra refresh is introduced as a non-normative error-resilience tool. Although the intra-refresh schemes based on the rate-distortion optimization (C?té et al., 2000; Stockhammer et al., 2002) are superior to the early heuristic intra-refresh strategies, these new schemes cannot yet accurately estimate the video distortion due to time-varying packet losses, and usually ignore the inter-frame error-propagation effect. Chiou…     

校园网多媒体视频网格系统的资源管理

本文通过分析多媒体视频教学技术在校园网应用中存在的问题,指出构建多媒体视频网格应用系统是改善校园网多媒体视频服务质量的有效方法。网格应用系统中的资源管理是整个校园网格系统的关键和基础,文中较详细的介绍了网格环境下资源的分类方法,资源信息的存储方式及资源的调度方法。     

基于流媒体技术的网络视频资源库的构建

信息技术的飞速发展,使以多媒体通信技术为基础的流媒体技术得到了越来越广泛的应用。流媒体以其边播放边下栽的特性,成功地解决了多媒体信息网上传输的问题,使网络教学中的学习资源建设模式发生了重要变化。     

基于IP专网的多媒体教室数字视频监控系统研究

近年来,随着计算机网络技术和多媒体技术的快速发展,基于网络的数字视频监控技术的开发和应用已经成为网络应用的一个热点。文章简要介绍了视频监控系统的发展历史,分析了数字视频监控系统的优点、基于IP专网的数字视频监控系统的安防要求、风险分析与需求分析。重点阐述了北京科技大学现代教育中心建设的基于IP专网的数字视频监控系统的设计原则及功能实现,以及该系统的优势。     

The speaker/gender effect: does the speaker’s gender matter when presenting auditory text in multimedia messages?

Current cognitive multimedia design theories provide several guidelines on how to integrate verbal and pictorial information. However, the recommendations for the design of auditory texts (narrations) are still fragmentary, especially with regard to the characteristics of the voices used. In the current paper, a fundamental question is addressed, namely, whether to use a male or a female speaker. In two experiments, learners studied dynamic visualizations on probability theory that were accompanied by narrations. The learner’s gender and the speaker’s gender served as between-subjects variables. In the first study, learners were randomly assigned to speakers of different gender. In the second study, learners could choose among different speakers. The results show that learners achieved better learning outcomes when the narration was presented by a female speaker rather than a male speaker irrespective of the learner’s gender (speaker/gender effect). Being given the choice, learners preferred female speakers, but this individual preference had no impact on learning outcomes. The results suggest augmenting purely cognitive approaches to multimedia design by social-motivational assumptions.     

Delphi中基于VideocapX ActiveX控件的视频采集系统的实现

以WindowsXP作为开发平台,Delphi2005作为开发工具,采用VideocapX ActiveX控件,实现了视频的采集和传输。实验结果表明：在开发视频采集和传输系统的过程中使用ActiveX视频控件是很容易实现的。     

Physical education and sport science undergraduate students as multimedia and web developers: Moving from the user’s to the creator’s perspective

The increasing importance that Information and Communication Technologies (ICT) have been gaining for Physical Education (PE) and sports pedagogy has generated the need to prepare ICT-proficient prospective PE teachers within PE and sport science university departments. This study was aimed at: (a) the design and implementation of two project-based elective courses on ICT in education (entitled ‘Informatics in Education’ and ‘Computers in Physical Education Teaching’) for the undergraduate students of a PE and sport science department, and (b) the investigation of students’ responses to the courses and instructor’s experiences from organizing and imparting the courses. The courses were focused on educational multimedia and web development for PE. Twenty-three students that had attended ‘Informatics in Education’ and 13 students that had attended ‘Computers in Physical Education Teaching’ participated in the study. Research data were collected through student questionnaires and instructor’s notes. It was found that students were helped to acquire basic multimedia and web development skills for educational purposes, and that their responses to the courses were positive overall. The courses fulfilled students’ expectations and were successful in equipping students with self-confidence in their ability to make use of ICT in PE courses and to construct multimedia and web-based learning materials. Furthermore, students were provided with opportunities to express their creativity and improve their future instructional practices. However, the study also brought to light the various difficulties and challenges of training prospective PE teachers in the didactical utilization of ICT at undergraduate level.     

An application-layer based centralized information access control for VPN

INTRODUCTION AND BACKGROUND In the last decade, as the Internet becomes a popular low-cost backbone infrastructure, many or- ganizations and companies use it to establish their secure private network, which is known as VPN (Virtual Private Network) technology (Cohen, 2003). Generally, VPN implements confidentiality of data, message integrity and endpoint authentication by the security protocols (such as IPSec: IP Security (Kent and Atkinson, 1998) and TLS/SSL: Transport Lay…     

视频信号压缩标准探析

通过对多媒体视频信号技术的探讨,结合MPEG压缩标准,阐述了在多媒体视频处理中所涉及到的基础知识。     

Qualitative Differences Between Learning Environments Using Videos in Small Groups and Whole Class Discussions: A Preliminary Study in Physics

Interactivity, group learning and student engagement are accepted as key features of social constructivist learning theories. The challenge is to understand the interplay between such features in different learning environments. This study focused on the qualitative differences between two interventions—small-groups and whole-class discussions. In both interventions, three short video slices on the abstract topic ‘the physics of superconductivity’ were interspersed with the different discussion styles. The video slices are based on the Bruner stages. Twenty-nine first year university physics students completed a pre-test, underwent the intervention and completed a post-test. The remainder of the data were collected from student drawings, video recordings, observer notes and facilitator feedback. Results indicate that the use of the video slices in both interventions were successful in changing students’ understandings of superconductivity. However, the small groups treatment tended to facilitate questioning, meaning-making and subsequent changes of ideas more so than the whole class discussions. Implications for research and practice are discussed.     

Learning to observe: using video to improve preservice mathematics teachers’ ability to notice

Video has assumed an increasingly prominent role in teacher education, particularly in the form of the viewing of videotaped class lessons by preservice teachers. Yet there is little research that confirms whether preservice teachers attend to the aspects of the video(s) that teacher educators anticipate or desire. This article explores this issue and reports on the impact of video viewing as a means to improve teachers’ ability to be observers of classroom practice. We utilized a pre- and post-test design to measure the quantity and type of classroom events that preservice mathematics teachers noticed before and after a teaching methods course where improving observation skills was an explicit goal. The results of the pre-assessment suggest that preservice teachers generally do not enter teaching methods courses with well-developed observation skills. The post-assessment indicates that the course led to significant increases in preservice teachers’ observation skills, particularly in teachers’ ability to notice features of the classroom environment, mathematical content of a lesson, and teacher and student communication during a lesson.

Collaboration, Engagement & Fun: How Youth Preferences in Video Gaming can Inform 21st Century Education

In this content analysis study, researchers explored middle school students’ preference for playing video games and the possible implications for learning environments. During two-week, summer sessions, learners played videos games and answered questions related to their preferences in different settings. Students’ preferences and justifications for playing alone or in company are described. Results shows that middle school students prefer to work in groups motivated by companionship, collaboration, competition, and challenge. The article concludes showing the relevance of using video games to emphasize 21st century skills in learners.     

Improving the usability of the user interface for a digital textbook platform for elementary-school students

Usability is critical to the development of a user-friendly digital textbook platform interface, yet thorough research on interface development based on usability principles is in short supply. This study addresses that need by looking at usability attributes and corresponding design elements from a learning perspective. The researchers used a student survey, log files, and an expert heuristic evaluation to analyze needs for revision in the user interface of the existing Korea Education Research Information Service digital textbook platform. After using suggestions derived from this analysis to develop a new platform prototype, they tested its user interface for usability through a cognitive walkthrough and a formative evaluation. The results show that the usability design elements identified through the use of this iterative design and evaluation model were essential to improving the usability of the user interface and thus facilitating users’ actions and learning processes.     

网络环境下的高校影视审美教育

信息技术的迅速发展,使高校学生通过网络轻易地接触到大量的影视作品,影视文化对学生的影响日益加大。而高校公共影视教育则相对滞后。这就要求高校影视审美教育必须审时度势,改革传统的教育教学模式,开展前瞻性研究,利用课堂讲授、校园文化和网络传播来架构立体的影视教育新体系。