Faithful sharing of screen contents is an important collaboration feature. Prior systems were designed to operate over constrained networks. They performed poorly even without such bottlenecks. To build a high performance screen sharing system, we empirically analyzed screen contents for a variety of scenarios. We showed that screen updates were sporadic with long periods of inactivity. When active, screens were updated at far higher rates than was supported by earlier systems. The mismatch was pronounced for interactive scenarios. Even during active screen updates, the number of updated pixels were frequently small. We showed that crucial information can be lost if individual updates were merged. When the available system resources could not support high capture rates, we showed ways in which updates can be effectively collapsed. We showed that Zlib lossless compression performed poorly for screen updates. By analyzing the screen pixels, we developed a practical transformation that significantly improved compression rates. Our system captured 240 updates per second while only using 4.6 Mbps for interactive scenarios. Still, while playing movies in fullscreen mode, our approach could not achieve higher capture rates than prior systems; the CPU remains the bottleneck. A system that incorporates our findings is deployed within the lab.

DisplayCast is a many to many screen sharing system that is targeted towards Intranet scenarios. The capture software runs on all computers whose screens need to be shared. It uses an application agnostic screen capture mechanism that creates a sequence of pixmap images of the screen updates. It transforms these pixmaps to vastly improve the lossless Zlib compression performance. These algorithms were developed after an extensive analysis of typical screen contents. DisplayCast shares the processor and network resources required for screen capture, compression and transmission with host applications whose output needs to be shared. It balances the need for high performance screen capture with reducing its resource interference with user applications. DisplayCast uses Zeroconf for naming and asynchronous location. It provides support for Cisco WiFi and Bluetooth based localization. It also includes a HTTP/REST based controller for remote session initiation and control. DisplayCast supports screen capture and playback in computers running Windows 7 and Mac OS X operating systems. Remote screens can be archived into a H.264 encoded movie on a Mac. They can also be played back in real time on Apple iPhones and iPads. The software is released under a New BSD license.

Poster

The Usable Smart Environment project (USE) aims at designing easy-to-use, highly functional next-generation conference rooms. Our first design prototype focuses on creating a "no wizards" room for an American executive; that is, a room the executive could walk into and use by himself, without help from a technologist. A key idea in the USE framework is that customization is one of the best ways to create a smooth user experience. Since the system needs to fit both with the personal leadership style of the executive and the corporation's meeting culture, we began the design process by exploring the work flow in and around meetings attended by the executive. Based on our work flow analysis and the scenarios we developed from it, USE developed a flexible, extensible architecture specifically designed to enhance ease of use in smart environment technologies. The architecture allows customization and personalization of smart environments for particular people and groups, types of work, and specific physical spaces. The first USE room was designed for FXPAL's executive "Ian" and installed in Niji, a small executive conference room at FXPAL. The room Niji currently contains two large interactive whiteboards for projection of presentation material, for annotations using a digital whiteboard, or for teleconferencing; a Tandberg teleconferencing system; an RFID authentication plus biometric identification system; printing via network; a PDA-based simple controller, and a tabletop touch-screen console. The console is used for the USE room control interface, which controls and switches between all of the equipment mentioned above.

As the use of rich media in mobile devices and smart environments becomes more sophisticated, so must the design of the everyday objects used as controllers and interfaces. Many new interfaces simply tack electronic systems onto existing forms. However, an original physical design for a smart artefact, that integrates new systems as part of the form of the device, can enhance the end-use experience. The Convertible Podium is an experiment in the design of a smart artefact with complex integrated systems for the use of rich media in meeting rooms. It combines the highly designed look and feel of a modern lectern with systems that allow it to serve as a central control station for rich media manipulation. The interface emphasizes tangibility and ease of use in controlling multiple screens, multiple media sources (including mobile devices) and multiple distribution channels, and managing both data and personal representation in remote telepresence.

We describe our work-in-progress: a "wizard-free" conference room designed for ease of use, yet retaining next-generation functionality. Called USE (Usable Smart Environments), our system uses multi-display systems, immersive conferencing, and secure authentication. It is based in cross-cultural ethnographic studies on the way people use conference rooms. The USE project has developed a flexible, extensible architecture specifically designed to enhance ease of use in smart environment technologies. The architecture allows customization and personalization of smart environments for particular people and groups, types of work, and specific physical spaces. The system consists of a database of devices with attributes, rooms and meetings that implements a prototype-instance inheritance mechanism through which contextual information (e.g. IP addresses application settings, phone numbers for teleconferencing systems, etc.) can be associated

The Convertible Podium is a central control station for rich media in next-generation classrooms. It integrates flexible control systems for multimedia software and hardware, and is designed for use in classrooms with multiple screens, multiple media sources and multiple distribution channels. The built-in custom electronics and unique convertible podium frame allows intuitive conversion between use modes (either manual or automatic). The at-a-touch sound and light control system gives control over the classroom environment. Presentations can be pre-authored for effective performance, and quickly altered on the fly. The counter-weighted and motorized conversion system allows one person to change modes simply by lifting the top of the Podium to the correct position for each mode. The Podium is lightweight, mobile, and wireless, and features an onboard 21" LCD display, document cameras and other capture devices, tangible controls for hardware and software, and also possesses embedded RFID sensing for automatic data retrieval and file management. It is designed to ease the tasks involved in authoring and presenting in a rich media classroom, as well as supporting remote telepresence and integration with other mobile devices.

As the use of rich media in mobile devices and smart environments becomes more sophisticated, so must the design of the everyday objects used as containers or controllers. Rather than simply tacking electronics onto existing furniture or other objects, the design of a smart object can enhance existing ap-plications in unexpected ways. The Convertible Podium is an experiment in the design of a smart object with complex integrated systems, combining the highly designed look and feel of a modern lectern with systems that allow it to serve as a central control station for rich media manipulation in next-generation confer-ence rooms. It enables easy control of multiple independent screens, multiple media sources (including mobile devices) and multiple distribution channels. The Podium is designed to ease the tasks involved in authoring and presenting in a rich media meeting room, as well as supporting remote telepresence and in-tegration with mobile devices.

In a meeting room environment with multiple public wall displays and personal notebook computers, it is possible to design a highly interactive experience for manipulating and annotating slides. For the public displays, we present the ModSlideShow system with a discrete modular model for linking the displays into groups, along with a gestural interface for manipulating the flow of slides within a display group. For the applications on personal devices, an augmented reality widget with panoramic video supports interaction among the various displays. This widget is integrated into our NoteLook 3.0 application for annotating, capturing and beaming slides on pen-based notebook computers.

FlySPEC is a video camera system designed for real-time remote operation. A hybrid design combines the high resolution possible using an optomechanical video camera, with the wide field of view always available from a panoramic camera. The control system integrates requests from multiple users with the result that each controls a virtual camera. The control system seamlessly integrates manual and fully automatic control. It supports a range of options from untended automatic to full manual control, and the system can learn control strategies from user requests. Additionally, the panoramic view is always available for an intuitive interface, and objects are never out of view regardless of the zoom factor. We present the system architecture, an information-theoretic approach to combining panoramic and zoomed images to optimally satisfy user requests, and experimental results that show the FlySPEC system significantly assists users in a remote inspection tasks.

This paper presents a camera system called FlySPEC. In contrast to a traditional camera system that provides the same video stream to every user, FlySPEC can simultaneously serve different video-viewing requests. This flexibility allows users to conveniently participate in a seminar or meeting at their own pace. Meanwhile, the FlySPEC system provides a seamless blend of manual control and automation. With this control mix, users can easily make tradeoffs between video capture effort and video quality. The FlySPEC camera is constructed by installing a set of Pan/Tilt/Zoom (PTZ) cameras near a high-resolution panoramic camera. While the panoramic camera provides the basic functionality of serving different viewing requests, the PTZ camera is managed by our algorithm to improve the overall video quality that may affect users watching details. The video resolution improvements from using different camera management strategies are compared in the experimental section.

To meet the diverse needs of business, education, and personal video users, the authors developed three visual interfaces that help identify potentially useful or relevant video segments. In such interfaces, keyframes-still images automatically extracted from video footage-can distinguish videos, summarize them, and provide access points. Well-chosen keyframes enhance a listing's visual appeal and help users select videos. Keyframe selection can vary depending on the application's requirements: A visual summary of a video-captured meeting may require only a few highlight keyframes, a video editing system might need a keyframe for every clip, while a browsing interface requires an even distribution of keyframes over the video's full length. The authors conducted user studies for each of their three interfaces, gathering input for subsequent interface improvements. The studies revealed that finding a similarity measure for collecting video clips into groups that more closely match human perception poses a challenge. Another challenge is to further improve the video-segmentation algorithm used for selecting keyframes. A new version will provide users with more information and control without sacrificing the interface's ease of use.

Hitchcock is a system to simplify the process of editing video. Its key features are the use of automatic analysis to find the best quality video clips, an algorithm to cluster those clips into meaningful piles, and an intuitive user interface for combining the desired clips into a final video. We conducted a user study to determine how the automatic clip creation and pile navigation support users in the editing process. The study showed that users liked the ease-of-use afforded by automation, but occasionally had problems navigating and overriding the automated editing decisions. These findings demonstrate the need for a proper balance between automation and user control. Thus, we built a new version of Hitchcock that retains the automatic editing features, but provides additional controls for navigation and for allowing users to modify the system decisions.

R. Wakikawa, J. Trevor, B. N. Schilit, J. Boreczky.

Hitchcock is a system that allows users to easily create custom videos from raw video shot with a standard video camera. In contrast to other video editing systems, Hitchcock uses automatic analysis to determine the suitability of portions of the raw video. Unsuitable video typically has fast or erratic camera motion. Hitchcock first analyzes video to identify the type and amount of camera motion: fast pan, slow zoom, etc. Based on this analysis, a numerical "unsuitability" score is computed for each frame of the video. Combined with standard editing rules, this score is used to identify clips for inclusion in the final video and to select their start and end points. To create a custom video, the user drags keyframes corresponding to the desired clips into a storyboard. Users can lengthen or shorten the clip without specifying the start and end frames explicitly. Clip lengths are balanced automatically using a spring-based algorithm.

In accessing large collections of digitized videos, it is often difficult to find both the appropriate video file and the portion of the video that is of interest. This paper describes a novel technique for determining keyframes that are different from each other and provide a good representation of the whole video. We use keyframes to distinguish videos from each other, to summarize videos, and to provide access points into them. The technique can determine any number of keyframes by clustering the frames in a video and by selecting a representative frame from each cluster. Temporal constraints are used to filter out some clusters and to determine the representative frame for a cluster. Desirable visual features can be emphasized in the set of keyframes. An application for browsing a collection of videos makes use of the keyframes to support skimming and to provide visual summaries.

We describe a way to make a hypermedia meeting record from multimedia meeting documents by automatically generating links through image matching. In particular, we look at video recordings and scanned paper handouts of presentation slides with ink annotations. The algorithm that we employ is the Discrete Cosine Transform (DCT). Interactions with multipath links and paper interfaces are discussed.

We present and interactive system that allows a user to locate regions of video that are similar to a video query. Thus segments of video can be found by simply providing an example of the video of interest. The user selects a video segment for the query from either a static frame-based interface or a video player. A statistical model of the query is calculated on-the-fly, and is used to find similar regions of video. The similarity measure is based on a Gaussian model of reduced frame image transform coefficients. Similarity in a single video is displayed in the Metadata Media Player. The player can be used to navigate through the video by jumping between regions of similarity. Similarity can be rapidly calculated for multiple video files as well. These results are displayed in MBase, a Web-based video browser that allows similarity in multiple video files to be visualized simultaneously.

This paper presents a method for generating compact pictorial summarizations of video. We developed a novel approach for selecting still images from a video suitable for summarizing the video and for providing entry points into it. Images are laid out in a compact, visually pleasing display reminiscent of a comic book or Japanese manga. Users can explore the video by interacting with the presented summary. Links from each keyframe start video playback and/or present additional detail. Captions can be added to presentation frames to include commentary or descriptions such as the minutes of a recorded meeting. We conducted a study to compare variants of our summarization technique. The study participants judged the manga summary to be significantly better than the other two conditions with respect to their suitability for summaries and navigation, and their visual appeal.

This paper presents methods for automatically creating pictorial video summaries that resemble comic books. The relative importance of video segments is computed from their length and novelty. Image and audio analysis is used to automatically detect and emphasize meaningful events. Based on this importance measure, we choose relevant keyframes. Selected keyframes are sized by importance, and then efficiently packed into a pictorial summary. We present a quantitative measure of how well a summary captures the salient events in a video, and show how it can be used to improve our summaries. The result is a compact and visually pleasing summary that captures semantically important events, and is suitable for printing or Web access. Such a summary can be further enhanced by including text captions derived from OCR or other methods. We describe how the automatically generated summaries are used to simplify access to a large collection of videos.

When reviewing collections of video such as recorded meetings or presentations, users are often interested only in an overview or short segments of these documents. We present techniques that use automatic feature analysis, such as slide detection and applause detection, to help locate the desired video and to navigate to regions of interest within it. We built a web-based interface that graphically presents information about the contents of each video in a collection such as its keyframes and the distribution of a particular feature over time. A media player is tightly integrated with the web interface. It supports navigation within a selected file by visualiz-ing confidence scores for the presence of features and by using them as index points. We conducted a user study to refine the usability of these tools.

This paper describes a method for finding segments in video-recorded meetings that correspond to presentations. These segments serve as indexes into the recorded meeting. The system automatically detects intervals of video that correspond to presentation slides. We assume that only one person speaks during an interval when slides are detected. Thus these intervals can be used as training data for a speaker spotting system. An HMM is automatically constructed and trained on the audio data from each slide interval. A Viterbi alignment then resegments the audio according to speaker. Since the same speaker may talk across multiple slide intervals, the acoustic data from these intervals is clustered to yield an estimate of the number of distinct speakers and their order. This allows the individual presentations in the video to be identified from the location of each presenter's speech. Results are presented for a corpus of six meeting videos.

In accessing large collections of digitized videos, it is often difficult to find both the appropriate video file and the portion of the video that is of interest. This paper describes a novel technique for determining keyframes that are different from each other and provide a good representation of the whole video. We use keyframes to distinguish videos from each other, to summarize videos, and to provide access points into them. The technique can determine any number of keyframes by clustering the frames in a video and by selecting a representative frame from each cluster. Temporal constraints are used to filter out some clusters and to determine the representative frame for a cluster. Desirable visual features can be emphasized in the set of keyframes. An application for browsing a collection of videos makes use of the keyframes to support skimming and to provide visual summaries.