基于Darwin的多平台多用户直播、点播系统设计

针对当前多平台多用户播放手机客户端直播、录像视频的需求,提出了一种手机移动客户端主动推送视频流到Darwin服务器直播、转播及录制供多平台多用户播放的解决方案。利用开源的流媒体服务器Darwin结合开源库mp4v2实现将手机客户端上传的视频流实时转发和录制;PC平台客户端由开源RTSP架构live555结合开源编解码库ffmpeg实现视频直播、点播播放。Web平台客户端由Html5技术实现视频点播,由插件实现直播。实验结果表明,该方案在现有的3G网络上具有较高的实时性和稳定性,视频具有较好的质量,能满足多平台多用户视频直播、点播播放的要求。     

基于流媒体的移动视频直播系统的设计与实现

视频直播是最能体现媒体信息实时传播的媒体形态,介绍了一个利用3G/4G手机进行视频拍摄和传输的移动直播系统。分析了当今移动直播系统的发展趋势,介绍了如何设计并实现一个基于流媒体技术的移动视频直播系统。实际测试结果表明,用户可以随时随地地利用3G/4G的iPhone手机进行直播,观众可以在远程PC端利用VLC播放器进行观看,提高直播系统的便捷性。     

An efficient hybrid push-pull methodology for peer-to-peer video live streaming system on mobile broadcasting social media

With the rapid growth of wireless communication technology, the availability of highly flexible and video-friendly mobile terminal platforms (such as smartphones and tablets), the emergence of major video content providers (like YouTube, Ustream, and PPTV, which provide a large catalog of attractive contents), Peer-to-Peer (P2P) live video streaming over the wireless and Internet is becoming more and more attractive to users. One of the main challenges is to provide a good quality of service though the dynamic behavior of the network. Traditionally, tree-based model uses a push method, that broadcaster transfers data to other users. This model has low start-up delay. However, there are two main problems in this method: if the bandwidth of an internal node is low, children nodes may lose data and when an internal node failure, other nodes can’t receive data until completing the recovery of the tree. On the other hand, mesh-based model uses a pull method, has low bandwidth of a neighbor node by pulling necessary data from a number of neighbor nodes. However, mesh-based model requires large buffers to support pull data from neighbor peers and there is an adjustment between minimum delay by sending pull request and overhead of whole system. So, both models have their own strengths and weaknesses. This paper proposes a new hybrid push-pull live P2P video streaming protocol called MobileCast that combines the benefits of pull and push mechanisms for live video delivery. We present new topology for P2P network with more stable and provide better video streaming quality. Our main goal is to minimize the network end-to-end delay, startup time, overhead, packet loss compared to the pure mesh networks, pure tree networks and provide a good quality of service though the dynamic behavior of the network.

     

OCS: An effective caching scheme for video streaming on overlay networks

Video streaming is vital for many important applications such as distance learning, digital video libraries, and movie-on-demand. Since video streaming requires significant server and networking resources, caching has been used to reduce the demand on these resources. In this paper, we propose a novel collaboration scheme for video caching on overlay networks, called Overlay Caching Scheme (OCS), to further minimize service delays and loads placed on an overlay network for video streaming applications. OCS is not a centralized nor a hierarchical collaborative scheme. Despite its design simplicity, OCS effectively uses an aggregate storage space and capability of distributed overlay nodes to cache popular videos and serve nearby clients. Moreover, OCS is light-weight and adaptive to clients’ locations and request patterns. We also investigate other video caching techniques for overlay networks including both collaborative and non-collaborative ones. Compared with these techniques on topologies inspired from actual networks, OCS offers extremely low average service delays and approximately half the server load. OCS also offers smaller network load in most cases in our study.

基于Flex、Red5和MongoDB的视频直播、录制及存储系统设计

为改善以往网络视频直播或点播过程中播放不流畅的情况和寻找大量视频数据的存储策略,提出了一种实时的视频直播、录制及存储系统的整体设计方案。利用开源的流媒体服务器Red5结合富互联网技术Flex实现直播和录制;通过开源NoSQL数据库MongoDB将录制的视频数据进行存储。实际测试结果表明,该平台能满足系统在多用户访问和数据存储方面的要求。     

Communication goals and online persuasion: An empirical examination

Computer-mediated communication (CMC) is frequently applied as a tool for organizational marketing and consumer research. This paper explores the underlying structure of message receivers’ communication goals and their impact on persuasiveness in the context of CMC. Extending prior research on the structure of primary and secondary goals, we identified five specific communication goals that are important to receivers. We conducted an online exercise in which subjects respond to a message requesting them to volunteer their time. The results demonstrate all five communication goals are important to one or more indicators of persuasiveness, including attitude toward the issue, source credibility, perceived information quality, and behavioral intention to comply with the request.     

The influence of user-generated content on traveler behavior: An empirical investigation on the effects of e-word-of-mouth to hotel online bookings

The increasing use of web 2.0 applications has generated numerous online user reviews. Prior studies have revealed the influence of user-generated reviews on the sales of products such as CDs, books, and movies. However, the influence of online user-generated reviews in the tourism industry is still largely unknown both to tourism researchers and practitioners. To bridge this knowledge gap in tourism management, we conducted an empirical study to identify the impact of online user-generated reviews on business performance using data extracted from a major online travel agency in China. The empirical findings show that traveler reviews have a significant impact on online sales, with a 10 percent increase in traveler review ratings boosting online bookings by more than five percent. Our results highlight the importance of online user-generated reviews to business performance in tourism.     

Privacy and biometrics: An empirical examination of employee concerns

Advances in authentication technology have led to a proliferation of biometric-based systems in the workplace. Although biometric technologies offer organizations a cost-effective method of increasing security, employees are often hesitant to permit use. The collection and storage of employee biometric data raises concerns about proper use of these intensely personal identifiers. This work draws from organizational privacy practices, electronic monitoring, procedural fairness, self-construal, and technology adoption theories. We investigate the effects of independent and interdependent self-construal on three newly developed dimensions of employee privacy concern related to organizational use of biometric technology. These dimensions include perceived accountability, perceived vulnerability, and perceived distrust toward the organization. We test the predictive power of our model using data from an organization deploying a new biometric system designed to track employee work assignments under the auspices of improving personnel safety. Results indicate that self-construal plays a significant role in the formulation of privacy concerns and both perceived accountability concerns and perceived vulnerability concerns are significant predictors of attitude toward using biometric technology in the workplace.     

MioStream: a peer-to-peer distributed live media streaming on the edge

Multimedia Tools and Applications - The typical centralized cloud model is poorly suited to latency-sensitive applications requiring low-latency and high-throughput. This paper proposes an...     

An integrated source transcoding and congestion control paradigmfor video streaming in the Internet

In this work we present an end-to-end optimized video streaming system comprising of synergistic interaction between a source packetization strategy and an efficient and responsive, TCP-friendly congestion control protocol [Linear Increase Multiplicative Decrease with History (LIMD/H)]. The proposed source packetization scheme transforms a scalable/layered video bitstream so as to provide graceful resilience to network packet drops. The congestion control mechanism provides low variation in transmission rate in steady state and at the same time is reactive and provably TCP-friendly. While the two constituent algorithms identified above are novel in their own right, a key aspect of this work is the integration of these algorithms in a simple yet effective framework. This “application-transport” layer interaction approach is used to maximize the expected delivered video quality at the receiver. The integrated framework allows our system to gracefully tolerate and quickly react to sudden changes in the available connection capacity due to the onset of congestion, as verified in our simulations     

WuKong: a practical video streaming service based on native BitTorrent and scalable video coding

Many researches on peer-to-peer video streaming have focused on dealing with highly dynamic, high-churn P2P environment. Most of P2P streaming protocols were modified from a P2P file sharing protocol. Inspired by the high performance on peer-to-peer file sharing of BitTorrent, we propose an overlaying streaming mechanism on the native BitTorrent protocol and realize a practical P2P video streaming service, called WuKong. WuKong not only takes advantages of BitTorrent but also combines the video scalability of layered video coding. In this paper, we depict an overlaid streaming mechanism in WuKong and an adaptive layer-downloading process to balance between the video quality and bandwidth utilization on heterogeneous peers. WuKong is carried out by using an open-sourced library of the BitTorrent protocol, coding schemes of the Windows Media Video (WMV), and the Scalable Video Coding (SVC). We measured and compared the service quality of end-users served by WuKong on heterogeneous peers. In addition, we evaluated the effectiveness of WuKong with peers that are randomly joining and leaving the P2P network. The results show that WuKong not only provides high quality P2P video streaming services but also supports different scaling abilities over heterogeneous devices.     

An empirical examination of the determinants of mobile purchase

As en emerging service, mobile purchase has not received wide adoption among users. Drawing on the trust and flow theory, this research identified the factors affecting user adoption of mobile purchase. We conducted data analysis with structural equation modeling (SEM). The results indicated that contextual offering has strong effects on trust, flow, and perceived usefulness. In addition, structural assurance affects trust. Trust affects flow, which further affects perceived usefulness. These three factors determine mobile purchase intention.     

Annotations for streaming video on the Web: system design and usage studies

Streaming video on the World Wide Web is being widely deployed, and workplace training and distance education are key applications. The ability to annotate video on the Web can provide significant added value in these and other areas. Written and spoken annotations can provide `in context' personal notes and can enable asynchronous collaboration among groups of users. With annotations, users are no longer limited to viewing content passively on the Web, but are free to add and share commentary and links, thus transforming the Web into an interactive medium. We discuss design considerations in constructing a collaborative video annotation system, and we introduce our prototype, called MRAS. We present preliminary data on the use of Web-based annotations for personal note-taking and for sharing notes in a distance education scenario. Users showed a strong preference for MRAS over pen-and-paper for taking notes, despite taking longer to do so. They also indicated that they would make more comments and questions with MRAS than in a `live' situation, and that sharing added substantial value.     

An empirical examination of the impact of computer information systems on users

This research investigates the effects of computer-based information systems on users and their jobs. Overall, based upon data collected from 101 users, the results show that information systems have a positive effect on four of the five core job dimensions (identity, significance, autonomy, and feedback). No significant impact is detected for the “skill variety” dimension. Results are also reported when users are broken down according to their position in the management hierarchy, and their user type (primary, secondary, end-users).     

The leveraging influence of strategic alignment on IT investment: An empirical examination

Businesses have invested enormous sums in information technology (IT). The challenge now is to optimize these investments. We empirically examined the influence of the alignment between IS strategy and business strategy (strategic alignment) on the payoff of IT investment. Many studies have been performed on the value of IT investment and strategic alignment separately, in the past, but here we combined them by investigating the moderating affect of strategic alignment on the relationship between IT investment and firm performance for a group of manufacturing firms. The results indicated that there is a synergistic coupling between strategic alignment and IT investment with firm performance. Firms that have aligned IT and business strategies can invest in additional IT resources with some assurance that they will be leveraged substantially. One of our main contributions was in the examination of four differing perspectives of strategic alignment and their relationship with the payoff of IT investment.     

An empirical examination of the sustainability of social bookmarking websites

Given the continuous growth of social bookmarking sites, we investigated the reasons behind their sustainability as online social structures. Bookmarking sites offer users the option to post and tag web resources privately or to make them publicly available to other users of the sites. A prevalence of private tagging would threaten the sustainability of the social aspects at these sites. Using activity data from a sample of 1,000 users of Simpy, a popular social bookmarking site, we found that the majority of users contribute most of their tagged resources to the public repository, despite the option to keep them private. We also found that in social bookmarking sites there is a minority of extremely prolific contributors who are responsible for a large portion of public tagged resources. Finally, we found that new users make larger proportions of their contributions public than existing users and that there is a larger number of regular contributors to the site than irregular ones. All of these findings are consistent with the mechanisms predicted by a theoretical model of sustainable online social structures.     

An evaluation of streaming digital video resources in on- and off-campus engineering management education

A recent television documentary on the Columbia space shuttle disaster was converted to streaming digital video format for educational use by on- and off-campus students in an engineering management study unit examining issues in professional engineering ethics. An evaluation was conducted to assess the effectiveness of this new resource. Use of the video was optional, and about half of the class reported using the video, though usage was 90.0% for off-campus students. Most on-campus students accessed the video on-line, while all off-campus students accessed the video via CD-ROM. Off-campus students rated the educational value of the video higher than on-campus students, and were more likely to indicate that the video helped them understand the issues being studied. Most students were able to view the videos without any technical playback problems.     

On the impact of playout scheduling on the performance of peer-to-peer live streaming

In this paper we examine the impact of the adopted playout policy on the performance of P2P live streaming systems. We argue and demonstrate experimentally that (popular) playout policies which permit the divergence of the playout points of different nodes can deteriorate drastically the performance of P2P live streaming. Consequently, we argue in favor of keeping different playout points “near-in-time”, even if this requires sacrificing (dropping) some late frames that could otherwise be rendered (assuming no strict bidirectional interactivity requirements are in place). Such nearly synchronized playout policies create “positive correlation” with respect to the available frames at different playout buffers. Therefore, they increase the number of upstream relay nodes from which a node can pull frames and thus boost the playout quality of both single-parent (tree) and multiple-parent (mesh) systems. On the contrary, diverging playout points reduce the number of upstream parents that can offer a gapless relay of the stream. This is clearly undesirable and should be avoided as it contradicts the fundamental philosophy of P2P systems which is to supplement an original service point with as many additional ones presented by the very own users of the service.     

Group cohesion in organizational innovation: An empirical examination of ERP implementation

Enterprise Resource Planning systems present unique difficulties in implementation in that they typically involve changes to the entire organization and are a novel application for the organization. These characteristics add to the importance of making groups more cohesive in their goals, commitment, and ability to work toward completion of the new system project. Such cohesiveness is built partly through the willingness of the team members to participate and commitment to learning the new system. To determine if these relationships hold, a survey of users and managers in Taiwan was conducted to test a model derived from social capital theory. The data support the positive relationships between group cohesion and both willingness to participate and commitment to learning. Group cohesion is likewise positively related to meeting management goals. Resources within an organization should support the climate of learning and the building of team participation.     

An empirical analysis of the influence of urban form on household travel and energy consumption

Using the 2001 National Household Travel Survey (NHTS) data, this paper empirically examines the effects of urban land use characteristics on household travel and transportation energy consumption in the Baltimore metropolitan area. The results of regression analysis show that different built environment measures lead to substantially different findings regarding the importance of urban form in influencing travel behavior. Among the built environment variables used in the analysis, accessibility provides much more explanatory power than density, design and diversity measures. Moreover, this study explores approaches to modeling the connection between urban form and household transportation energy consumption. Applying Structural Equation Models (SEMs), we found that urban form does not have a direct effect either on VMT or on vehicle energy consumption. The indirect effect, however, is significant and negative, which suggests that urban form affects household travel and energy consumption through other channels. In addition, household socio-economic characteristics, such as gender and number of vehicles, and vehicle characteristics also show significant relationships between VMT and energy consumption. This empirical effort helps us understand the major data and methodology challenges.