The impact of scaling on a multimedia connection architecture

As the last two meetings of the Internet Engineering Task Force have shown, the demand for Internet teleconferencing has arrived. Packet audio and video have now been multicast to approximately 170 different hosts in ten countries, and for upcoming meetings the number of remote participants is likely to be substantially larger. Yet the network infrastructure to support wide-scale packet teleconferencing is not in place. These experiments represent a departure from the two- to ten-site telemeetings that are the norm today. They represent an increase in scale of multiple orders of magnitude in several interrelated dimensions.This paper discusses the impact of scaling on our efforts to define a multimedia teleconferencing architecture. Three scaling dimensions of particular interest are: (1) very large numbers of participants per conference, (2) many simultaneous teleconferences, and (3) a widely dispersed user population. Here we present a strawman architecture and describe how conference-specific information is captured, then conveyed among end systems. We provide a comparison of connection models and outline the tradeoffs and requirements that change as we travel along each dimension of scale. In conclusion, we identify five critical needs for a scalable teleconferencing architecture.     

Real-Time Whiteboard Capture and Processing Using a Video Camera for Remote Collaboration

This paper describes our recently developed system which captures pen strokes on physical whiteboards in real time using an off-the-shelf video camera. Unlike many existing tools, our system does not instrument the pens or the whiteboard. It analyzes the sequence of captured video images in real time, classifies the pixels into whiteboard background, pen strokes and foreground objects (e.g., people in front of the whiteboard), extracts newly written pen strokes, and corrects the color to make the whiteboard completely white. This allows us to transmit whiteboard contents using very low bandwidth to remote meeting participants. Combined with other teleconferencing tools such as voice conference and application sharing, our system becomes a powerful tool to share ideas during online meetings     

Multidisciplinary Medical Team Meetings: An Analysis of Collaborative Working with Special Attention to Timing and Teleconferencing

In this paper we describe the process of a multi-disciplinary medical team meeting (MDTM), its functions and operation in colocated and teleconference discussions. Our goal is to identify the elements and mechanics of operation that enhance or threaten the dependability of the MDTM as a “system” and propose technologies and measures to make this system more reliable. In particular, we assess the effect of adding teleconferencing to the MDTM, and identify strengths and vulnerabilities introduced into the system by the addition of teleconferencing technology. We show that, with respect to the system’s external task environment, rhythms of execution of pre-meeting and post-meeting activities are critical for MDTM success and that the extension of the MDTM to wider geographic locations with teleconferencing might disrupt such rhythms thereby posing potential threats to dependability. On the other hand, an analysis of vocalisation patterns demonstrates that despite difficulties related to coordination and awareness in video-mediated communication (evidenced by increased time spent in case discussion, longer turns, decreased turn frequency and near lack of informal exchanges) the overall case discussion structure is unaffected by the addition of teleconferencing technology into proceedings.     

Understanding the functions of teleconferences for coordinating global software development projects

One of the dominant characteristics of contemporary software development is the global distribution of tasks, of developers, of information and of technologies. Undoubtedly, such distribution engenders new coordination challenges in the form of distance‐related interdependencies. One of the predominant processes of addressing these challenges is electronic meetings (or teleconferences). However, the functions of these meetings for coordination purposes are not yet understood. The distinctive conventions of teleconferences and their causal relationships that lead to optimal coordination of global software development (GSD) projects are also not yet understood. In this paper, the functions of teleconferences held by globally distributed software developers to coordinate their work in the face of global distribution of resources, cross‐site information interdependencies and continuously changing software requirements are analysed. The analysis is based on a qualitative study of how a subunit of 13 software developers, distributed across three sites in the USA and one in Republic of Ireland, used teleconferences to address its coordination challenges. The paper proffers a teleconference approach to GSD coordination by arguing that the functions of teleconferences manifest in software developers' multitasking; their ready access to all their information as additional benefits; flexibility in their communicative behaviours; and a reduction in their structure overload. This approach draws attention to these manifestations as distinctive conventions of the de‐structured meeting, which de‐structuring is occasioned by organic information processing needs in teleconferencing. This approach also explains why the combination of global distribution and teleconferences is a strategic opportunity for information processing for software process coordination.     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.     

一种新型的P2P-SIP VoIP网络会议的研究与设计

针对SIP服务在C/S方式下网络电话会议部署中可能出现的单点失效和性能瓶颈问题,提出一种新型的分层服务下的P2P-SIP网络电话会议解决方案,在VIP和Ordinary两个层次上分别通过直传和应用层组播分发媒体数据流,该设计基于分布式结构化P2P网络,采用信令集中、媒体流分布的会议模型,能满足参与人数较多的大型VoIP网络会议的需要.     

Personal Varrier: Autostereoscopic virtual reality display for distributed scientific visualization

As scientific data sets increase in size, dimensionality, and complexity, new high resolution, interactive, collaborative networked display systems are required to view them in real-time. Increasingly, the principles of virtual reality (VR) are being applied to modern scientific visualization. One of the tenets of VR is stereoscopic (stereo or 3d) display; however the need to wear stereo glasses or other gear to experience the virtual world is encumbering and hinders other positive aspects of VR such as collaboration. Autostereoscopic (autostereo) displays presented imagery in 3d without the need to wear glasses or other gear, but few qualify as VR displays. The Electronic Visualization Laboratory (EVL) at the University of Illinois at Chicago (UIC) has designed and built a single-screen version of its 35-panel tiled Varrier display, called Personal Varrier. Based on a static parallax barrier and the Varrier computational method, Personal Varrier provides a quality 3d autostereo experience in an economical, compact form factor. The system debuted at iGrid 2005 in San Diego, CA, accompanied by a suite of distributed and local scientific visualization and 3d teleconferencing applications. The CAVEwave National LambdaRail (NLR) network was vital to the success of the stereo teleconferencing.     

均衡虚拟空间会议系统的混频时延和混频器数量的技术研究

合成虚拟空间会议系统(VST)的一个需要考虑的重要因素是混频器数量和混频时延的关系，其中混频器数量影响系统的成本，而混频时延影响系统的实时性，降低系统的混频时延和降低混频器数量是一对矛盾的问题．基于VST系统的通信效率与混频器关系，提出了在保证系统通信容忍的时延情况下，选取最少的混频器数量，以及在分层结构中系统通信的最小时延策略．采用这种策略能够有效地保证VST系统提供较高质量的服务时延和较低成本的混频．     

Design of a microcomputer-based meetings system

This paper describes the design and implementation of a meetings system using a microcomputer. In this control system, the following achievements were made: counting and checking the voting in a very short time; establishing who is/is not present at the meeting; establishing whether/not the meeting is quorate; and controlling the debate by being able to call various members to speak.The meetings system provides most of the functions of a manual system but significantly reduces the time wastage — and hence the waste of money — by allowing the chairman and the members of the meeting to communicate with each other by way of electronic signals in a controlled manner and by relegating routine counting and listchecking tasks to a microcomputer.     

Synchronization-Oriented Placement and Retrieval Strategies for Delay-Sensitive Media Streams

Multimedia data include text,image,audio and video,etc.Recent developments and advances in the areas of mass storage technology and high speed networks make it feasible for multimedia computing systems to offer services such as multimedia e-mial,teleconferencing and various vivid games.The storage and retrieval of multimedia data are two of the most important technologies in the futre multimedia systems.This paper analyzes the synchronization requirements of the delay-sensitive media streams,classifies the synchronization hierarchically and proposes several effective strategies for the intra-media and inter-media data placement problems.     

Gaze perception and awareness in smart devices

Eye contact and gaze awareness play a significant role for conveying emotions and intentions during face-to-face conversation. Humans can perceive each other's gaze quite naturally and accurately. However, the gaze awareness/perception are ambiguous during video teleconferencing performed by computer-based devices (such as laptops, tablet, and smart-phones). The reasons for this ambiguity are the (i) camera position relative to the screen and (ii) 2D rendition of 3D human face i.e., the 2D screen is unable to deliver an accurate gaze during video teleconferencing. To solve this problem, researchers have proposed different hardware setups with complex software algorithms. The most recent solution for accurate gaze perception employs 3D interfaces, such as 3D screens and 3D face-masks. However, today commonly used video teleconferencing devices are smart devices with 2D screens. Therefore, there is a need to improve gaze awareness/perception in these smart devices. In this work, we have revisited the question; how to improve a remote user's gaze awareness among his/her collaborators. Our hypothesis is that ‘an accurate gaze perception can be achieved by the ‘3D embodiment’ of a remote user's head gesture during video teleconferencing’. We have prototyped an embodied telepresence system (ETS) for the 3D embodiment of a remote user's head. Our ETS is based on a 3-DOF neck robot with a mounted smart device (tablet PC). The electromechanical platform in combination with a smart device is a novel setup that is used for studying gaze awareness/perception in 2D screen-based smart devices during video teleconferencing. Two important gaze-related issues are considered in this work; namely (i) ‘Mona-Lisa Gaze Effect’ – the gaze is always directed at the person independent of his position in the room, and (ii) ‘Gaze Awareness/Faithfulness’ – the ability to perceive an accurate spatial relationship between the observing person and the object by an actor. Our results confirm that the 3D embodiment of a remote user head not only mitigates the Mona Lisa gaze effect but also supports three levels of gaze faithfulness, hence, accurately projecting the human gaze in distant space.     

Special Feature: Interactive Graphics Teleconferencing

Interactive graphic displays of layouts or design plans, already in widespread use as design aids, can be even more effective when used in conjunction with teleconferencing.     

Analyzing facial expressions for virtual conferencing

The authors present a model-based algorithm that estimates 3D motion and facial expressions from 2D image sequences showing head and shoulder scenes typical of video telephone and teleconferencing applications     

Requirements for a virtual collocation environment

We analyze how physically collocated teams work together now and what services they require to work together across distances, focusing on real time interactions because those interactions justify collocating teams today. We explain how Integrated Product Teams (IPTs) are organized in system development programs and how their physical collocation facilitates communication, collaboration, and coordination within the team. Interactions within IPTs take two forms: scheduled meetings and opportunistic interactions. Scenarios of scheduled IPT meetings help motivate and identify requirements for supporting distributed meetings. Opportunistic interactions are far more common than scheduled meetings and more difficult to observe and analyze because they are not scheduled or predictable.     

Learning about meetings

Most people participate in meetings almost every day, multiple times a day. The study of meetings is important, but also challenging, as it requires an understanding of social signals and complex interpersonal dynamics. Our aim in this work is to use a data-driven approach to the science of meetings. We provide tentative evidence that: (i) it is possible to automatically detect when during the meeting a key decision is taking place, from analyzing only the local dialogue acts, (ii) there are common patterns in the way social dialogue acts are interspersed throughout a meeting, (iii) at the time key decisions are made, the amount of time left in the meeting can be predicted from the amount of time that has passed, (iv) it is often possible to predict whether a proposal during a meeting will be accepted or rejected based entirely on the language (the set of persuasive words) used by the speaker.     

Teleconferencing — Pacnet experience and future prospects

The range of teleconferencing delivery systems, from full-motion video to audioconferencing, is reviewed. A general survey of usage then focuses on the Plymouth Audio Conferencing Network. Progress in the first six months is evaluated. Future developments, with particular reference to audiographic coferencing using micros, are outlined.     

Virtual meeting rooms: from observation to simulation

Much working time is spent in meetings and, as a consequence, meetings have become the subject of multidisciplinary research. Virtual Meeting Rooms (VMRs) are 3D virtual replicas of meeting rooms, where various modalities such as speech, gaze, distance, gestures and facial expressions can be controlled. This allows VMRs to be used to improve remote meeting participation, to visualize multimedia data and as an instrument for research into social interaction in meetings. This paper describes how these three uses can be realized in a VMR. We describe the process from observation through annotation to simulation and a model that describes the relations between the annotated features of verbal and non-verbal conversational behavior. As an example of social perception research in the VMR, we describe an experiment to assess human observers’ accuracy for head orientation.

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基于MPEG-4的真实感人脸技术

人脸建模与动画是计算机图形学中最富有挑战性的课题之一,可以广泛应用于计算机动画行业、游戏行业、远程会议、代理和化身等许多领域。根据MPEG-4关于人脸特征点的定义,利用一般人脸模型以及特定人的正面和侧面两幅照片,采用Dirichlet自由变形实现了从一般人脸模型到特定人脸模型的变形;再利用特定人的正面和侧面照片,采用纹理融合方法生成了真实感人脸。论文提出的真实感人脸技术具有方法简单、计算速度快、真实感强等优点。     

Optimal multicast routing with quality of service constraints

We consider the problem of optimal multicast routing with Quality of Service constraints motivated by the requirements of interactive continuous media communication, e.g., real-time teleconferencing. We concentrate on distributed algorithms for determining a tree over the network topology, rooted at the source and spanning the intended destinations. Quality of Service requirements for interactive continuous media typically impose constraints on some metric over the individual paths from the source to each destination, usually in the form of an upper bound on the delay. Thus, we focus on the problem of minimizing the cost of the tree while at the same time satisfying a common constraint over individual source-destination paths. We have shown that this problem is intractable, but have also devised centralized polynomial time heuristics that perform well. Here we present distributed algorithms to minimize tree cost while satisfying the constraints on the paths from the source to each destination.     

Immersive teleconference system based on human-robot-avatar interaction using head-tracking devices

This paper introduces a cost-efficient immersive teleconference system. Especially to enhance immersive interaction capability during one-to-many telecommunication, this paper concentrates on the design of a teleconference system that is composed of a set of robotic devices and web-based control/monitoring interfaces for human-robot-avatar interaction. To this end, we first propose a serverclient network model for human-machine interaction systems based on the latest HTML5 technology. As a hardware system for teleconferencing, the simplest robot is designed specially for remote users to be able to experience augmented reality naturally on live scenes. Modularized software systems are then explained in view of accessibility and functionality. This paper also describes how a human head motion is captured, synchronized with a robot in the real world, and rendered through an 3-D avatar in the augmented world for human-robot-avatar interaction. Finally, the proposed system is evaluated through a questionnaire survey that follows a series of user-experience tests.