Joint fingerprinting and encryption in hybrid domains for multimedia sharing in social networks

The advent of social networks and cloud computing has made social multimedia sharing in social networks become easier and more efficient. The lowered cost of redistribution, however, also invites much motivation for large-scale copyright infringement, so it is necessary to safeguard multimedia sharing for security and privacy. In this paper, we proposed a novel framework for joint fingerprinting and encryption (JFE) based on Cellular Automata (CA) and social network analysis (SNA) with the purpose of protecting media distribution in social networks. The motivation is to map the hierarchical community structure of social networks into the tree structure of Discrete Wavelet Transform (DWT) for fingerprinting and encryption. First, the fingerprint code is produced by using SNA. Then the obtained fingerprints are embedded into the DWT domain. Afterwards, CA is used for permutation in the DWT domain. Finally, the image is diffused with XOR operation in the spatial domain. The proposed method, to the best of our knowledge, is the first JFE method using CA and SNA in hybrid domains for security and privacy in social networks. The use of fingerprinting along with encryption can provide a double-layer protection for media sharing in social networks. Both theoretical analysis and experimental results validate the effectiveness of the proposed scheme.     

基于DirectShow的多媒体流系统设计与应用

阐述了DirectShow的基本原理,给出了基于DirectShow的应用系统开发的基本思想、基本方法.通过实例讨论了多媒体流的捕获和播放技术以及DirectShow过滤器和过滤器图管理器的构建和管理;讨论了利用Visual C 实现基于DirectShow的多媒体流系统开发的关键技术,并对多媒体系统实现的开发方法和编程过程做出说明,并给出核心代码.结果表明,在此基础上实现的多媒体应用系统,具有更好的可重用性和可扩展性,缩短了开发周期.     

一种可支持多路音频、视频同时播放的装置设计

介绍了一种可支持多路音频／视频同时播放的装置,该装置可用来实现电脑或电视等多媒体设备在播放多个视频画面的同时,获得互不干扰的音频输出。该装置中的数据缓存模块连接有多个音频／视频读取模块,音频／视频读取模块的输出端分别与音频输出接口和视频呈现模块连接。     

Feature set and architecture of a multimedia news system over an ATM network

In this paper we discuss a multimedia news system that we have developed in the Multimedia Information Research Laboratory at the University of Ottawa and beyond. We focus on the feature set—that is, the tools and facilities associated with the system. We explain the functionality of each and give some real examples of the system in action. We then outline the architecture—the system consists of a production server for document authoring, a conferencing system for collaborative news article creation, a content database for authors, a hypernews database for hypermedia news documents, a news database server with aging and archiving, and user sites. The goal was to have all components of the system communicating on OCRInet—an R&D ATM network in the Ottawa region. We then introduce the challenges of representing and browsing large video objects and to this end we introduce a novel solution that we call video-tiles. This video tool is an effective way to browse large news videos that are frequently connected with our multimedia news articles.     

Design and implementation of a multimedia CSCW platform

In this paper, a generic four-layer framework for computer supported cooperative work (CSCW) is proposed. With clear separation of functionalities in each layer of the framework, application developers could implement their specific CSCW applications easily. Based on the four-layer framework, the architecture of a general purpose CSCW platform is designed and implemented with the necessary functionalities to help the collaborations among group members. To provide the system with more features and user friendliness, multimedia processing and transmission capabilities for audio and video are incorporated into the platform. Features like application-sharing, group decision support, multimedia mail transmission, etc., are well implemented in the platform. Moreover, an efficient network transport protocol, called VXTP, is designed and implemented to avoid the transmission overhead of conventional TCP. The performance measurements using both VXTP and TCP are given in the paper for comparison. Lastly, compared with other CSCW systems, our design achieves greater flexibility and portability by adopting the generality philosophy in the framework.     

Indexing and Retrieval of Audio: A Survey

With more and more audio being captured and stored, there is a growing need for automatic audio indexing and retrieval techniques that can retrieve relevant audio pieces quickly on demand. This paper provides a comprehensive survey of audio indexing and retrieval techniques. We first describe main audio characteristics and features and discuss techniques for classifying audio into speech and music based on these features. Indexing and retrieval of speech and music is then described separately. Finally, significance of audio in multimedia indexing and retrieval is discussed.     

Design and Implementation of a Java-based Meeting Space over Internet

This paper describes the implementation of Java Meeting Space (JMS), a generic, extensible framework and environment for developing synchronous collaborative applications. The JMS framework is based on a fully object-oriented replicated architecture where the application instances and management services are all replicated at each site. JMS provides basic CSCW coordination services: session management and dynamic floor control services. As a framework, it provides a set of programming interfaces that allow an application developer to take advantage of coordination services in the runtime environment.     

When groups decide to use asynchronous online discussions: collaborative learning and social presence under a voluntary participation structure

The purpose of this study is to explore how groups decide to use asynchronous online discussion forums in a non-mandatory setting, and, after the group decision is made, how group members use online discussion forums to complete a collaborative learning project requiring complex data gathering and research processes. While a large body of research on computer-mediated communication (CMC) has documented successful intervention strategies to promote and sustain online discussion forums, little of the research has examined the use of online discussion forums in voluntarily contexts, wherein the decision to use online discussion forums is a personal decision and participation is not a graded component. This study approaches the research questions using a naturalistic case study of one graduate-level blended learning course with 55 students. Employing both student interviews and content analysis methods, this study revealed that the factors affecting the group decision to use online discussion forums are (1) successful or unsuccessful experiences during the first trial, (2) perceived affordances of CMC tools, and (3) the interplay between the nature of collaborative tasks and perceived efficiency. The content analysis of online postings in two voluntary groups revealed that when groups decided to use online discussion forums, participation levels were almost equal among individual group members, and discussion threads were sustained until the final completion of the collaborative project.     

Implementation of AVS Jizhun decoder with HW/SW partitioning on a coarse-grained reconfigurable multimedia system

In this paper,a TPP(Task-based Parallelization and Pipelining)scheme is proposed to implement AVS(Audio Video coding Standard)video decoding algorithm on REMUS(REconfigurable MUltimedia System),which is a coarse-grained reconfigurable multimedia system.An AVS decoder has been implemented with the consideration of HW/SW optimized partitioning.Several parallel techniques,such as MB(Macro-Block)-based parallel and block-based parallel techniques,and several pipeline techniques,such as MB level pipeline and block level pipeline techniques are adopted by hardware implementation,for performance improvement of the AVS decoder.Also,most computation-intensive tasks in AVS video standards,such as MC(Motion Compensation),IP(Intra Prediction),IDCT(Inverse Discrete Cosine Transform),REC(REConstruct)and DF(Deblocking Filter),are performed in the two RPUs(Reconfigurable Processing Units),which are the major computing engines of REMUS.Owing to the proposed scheme,the decoder introduced here can support AVS JP(Jizhun Profile)1920×1088@39fps streams when exploiting a 200 MHz working frequency.     

Using multimedia to teach inservice teachers: Impacts on learning, application, and retention

This study investigated teachers’ ability to learn, apply in lesson plans, and retain knowledge of classroom discourse from a single module of a multimedia professional development program, used with 39 K-12 teachers enrolled in two graduate courses. Data collection and analysis included: (a) teacher development of – and panel review of – lesson plans integrating discourse, and (b) follow-up teacher interviews one year later. The study found: (a) the video modeling in the module was effective in helping teachers learn, and (b) discourse strategies were learned, applied, and retained. Implications for professional development with multimedia to teach classroom discourse include: (a) recursive use, (b) reflection, (c) multiple examples, (d) counter examples, and (e) prompts for observation.     

基于AT89C2051的单户可视对讲门铃室内分机的设计

本文介绍一种基于单片机AT89C2501的单户可视对讲门铃室内分机的工作原理及软、硬件的设计与实现方法。     

Modulus consensus in a network of singularly perturbed systems with collaborative and antagonistic interactions

This paper addresses the modulus consensus in a network of singularly perturbed systems, all of which own multi-time scales characteristics. The interactions among the agents are collaborative and antagonistic interactions, and it can been modelled by a signed directed graph. Also, the effect of time-varying delay has been taken into account when modelling the agent dynamics. Based on singularly perturbed decomposition method, Kronecker product technique and the comparison principle, several sufficient conditions are presented under which networked singularly perturbed time-varying delay systems with collaborative and antagonistic interactions achieve modulus consensus. Moreover, the upper bound of singular perturbation parameter is deduced explicitly. Two simulation examples are presented to illustrate the validity of the proposed results.     

WIP and PPP: a comparison of two multimedia presentation systems in terms of the standard reference model

In this paper, the Standard Reference Model for IMMPS is used for analysing the architectural design of two multimedia presentation systems which have been built at DFKI over the past 10 years. We first present the systems as described by the authors and then compare them in terms of the reference model.     

BilVideo: Design and Implementation of a Video Database Management System

With the advances in information technology, the amount of multimedia data captured, produced, and stored is increasing rapidly. As a consequence, multimedia content is widely used for many applications in today’s world, and hence, a need for organizing this data, and accessing it from repositories with vast amount of information has been a driving stimulus both commercially and academically. In compliance with this inevitable trend, first image and especially later video database management systems have attracted a great deal of attention, since traditional database systems are designed to deal with alphanumeric information only, thereby not being suitable for multimedia data.In this paper, a prototype video database management system, which we call BilVideo, is introduced. The system architecture of BilVideo is original in that it provides full support for spatio-temporal queries that contain any combination of spatial, temporal, object-appearance, external-predicate, trajectory-projection, and similarity-based object-trajectory conditions by a rule-based system built on a knowledge-base, while utilizing an object-relational database to respond to semantic (keyword, event/activity, and category-based), color, shape, and texture queries. The parts of BilVideo (Fact-Extractor, Video-Annotator, its Web-based visual query interface, and its SQL-like textual query language) are presented, as well. Moreover, our query processing strategy is also briefly explained.This work is partially supported by the Scientific and Research Council of Turkey (TÜBİTAK) under Project Code 199E025, Turkish State Planning Organization (DPT) under Grant No. 2004K120720, and European Union under Grant No. FP6-507752 (MUSCLE Network of Excellence Project).     

Digital tools and challenges to institutional traditions of learning: technologies, social memory and the performative nature of learning

The purpose of this article is to offer some reflections on the relationships between digital technologies and learning. It is argued that activities of learning, as they have been practised within institutionalized schooling, are coming under increasing pressure from the developments of digital technologies and the capacities to store, access and manipulate information that such resources offer. Thus, the technologies do not merely support learning; they transform how we learn and how we come to interpret learning. The metaphors of learning currently emerging as relevant in the new media ecology emphasize the transformational and performative nature of such activities, and of knowing in general. These developments make the hybrid nature of human knowing and learning obvious; what we know and master is, to an increasing extent, a function of the mediating tools we are familiar with. At a theoretical and practical level, this implies that the interdependences between human agency, minds, bodies and technologies have to serve as foundations when attempting to understand and improve learning. Attempts to account for what people know without integrating their mastery of increasingly sophisticated technologies into the picture will lack ecological validity.     

Collaborative Technology in the Classroom: A Review of the GSS Research and a Research Framework

Over the past several years, a number of research studies have investigated the application of group support system (GSS) technology to the classroom. The purpose of this paper is twofold: (1) to summarize and assess what has been learned from this emerging body of research, and (2) to draw on the GSS and cooperative learning literatures to construct a framework to guide future studies. The review of research studies reported in this paper focuses on comparative studies investigating the synchronous GSS classroom environment. While research findings regarding the impacts of GSS on learning performance are somewhat mixed, early indications are encouraging and suggest that GSS may have a positive impact under certain situations. A framework based on the GSS and cooperative learning research is introduced that identifies the contextual, group process, and outcome factors that researchers may wish to consider when designing and interpreting future research studies in this area.     

Promoting collaborative skills in online university: comparing effects of games,mixed reality,social media,and other tools for ICT-supported pedagogical practices

ABSTRACT

This article analyses the development of collaborative skills through nine tools for information and communication technologies (ICT)-supported pedagogical practices, which are used in online universities. Using survey data for 930 online students at the Open University of Catalonia and partial least squares path modelling estimation techniques, three main findings emerged from the study. First, collaborative skills are directly explained by gamification and the use of mixed reality and social media in a socio-technical online learning context. Second, other tools for ICT-supported pedagogical practices (media content, wikis, open educational resources, personal webpages, personal cloud, and sharing files with fellow students and lecturers on the cloud) are not significant on collaborative skills development, when compared to use of games, mixed reality, and social media. Third, the analysis of indirect effects suggests that all four socio-technical factors (ICT, learning tasks, students, and organisation) existing in online university play a decisive, positive and significant role in collaborative skills development. Finally, these results are shown in science, technology, engineering, and mathematics (STEM) and non-STEM studies. Thus, gamification, mixed reality, and sharing files are significant ICT-supported pedagogical practices in STEM studies. On the other hand, gamification is the only significant tool in non-STEM studies. Results are very useful for new approaches to design a framework for learning-team effectiveness in computer-supported collaborative learning.     

Facilitating peer knowledge modeling: Effects of a knowledge awareness tool on collaborative learning outcomes and processes

We report an empirical study where we investigated the effects, on the collaborative outcomes and processes, of a cognition-related awareness tool providing learners with cues about their peer’s level of prior knowledge. Sixty-four university students participated in a remote computer-mediated dyadic learning scenario. Co-learners were provided (or not) with a visual representation of their peer’s level of prior knowledge through what we refer to as a knowledge awareness tool (KAT). The results show that, providing co-learners with objective cues about the level of their peer’s prior knowledge positively impacts learning outcomes. In addition, this effect seems to be mediated by the fact that co-learners provided with these objective cues become more accurate in estimating their partner’s knowledge - accuracy that predicts higher outcomes. Analyses on the process level of the verbal interactions indicate that the KAT seems to sensitize co-learners to the fragile nature of their partner’s as well as their own prior knowledge. The beneficial effect of the KAT seems to mainly rely on this induction of epistemic uncertainty that implicitly triggers compensation socio-cognitive strategies; strategies that appear to be beneficial to the learning process.     

The coordination of work activities: Cooperation and conflict in a hospital context

An understanding of the ways in which work coordination is achieved in practice is essential to the development of effective CSCW technologies. However, previous studies are limited in their focus on small, self-contained work groups. In this analysis of work coordination in a hospital context, a broader perspective was adopted, allowing examination of activities across time, group and location. The use of a relevant structured methodology and a focus on deviations from formal procedures enabled the consideration of a range of contextual factors in interaction: Important aspects of work coordination to emerge included: status influences on the effectiveness of working practices; the social and political uses of information; conflicts between work goals and between motivations for coordinating activities; the role of informal practices; and the use of formal procedures to regulate inter-group relations. The implications of these issues for CSCW design in the hospital context are illustrated.     

远程多媒体监控系统的实现和分析

文章介绍了远程多媒体监控系统的实现方法,并对多媒体监控系统的关键技术作为分析,本系统具有一定的通用性和可扩展性。