Elizabeth Sanocki

Browsing digital video

Video in digital format played on programmable devices presents opportunities for significantly enhancing the users viewing experience. For example, time compression and pause removal can shorten the viewing time for a video, textual and visual indices can allow personalized navigation through the content, and random-access digital storage allows instantaneous seeks into the content. To understand user behavior when such capabilities are available, we built a software video browsing application that combines many such features. We present results from a user study where users browsed video in six different categories: classroom lectures, conference presentations, entertainment shows, news, sports, and travel. Our results show that the most frequently used features were time compression, pause removal, and navigation using shot boundaries. Also, the behavior was different depending on the content type, and we present a classification. Finally, the users found the browser to be very useful. Two main reasons were: i) the ability to save time and ii) the feeling of control over what content they watched.

Time-compression: systems concerns, usage, and benefits

With the proliferation of online multimedia content and thepopularity of multimedia streaming systems, it is increasinglyuseful to be able to skim and browse multimedia quickly. A keytechnique that enables quick browsing of multimedia istime-compression. Prior research has described how speech can betime-compressed (shortened in duration) while preserving the pitchof the audio. However, client-server systems providing thisfunctionality have not been available. In this paper, we first describe the key tradeoffs faced bydesigners of streaming multimedia systems deployingtime-compression. The implementation tradeoffs primarily impact thegranularity of time-compression supported (discrete vs. continuous)and the latency (wait-time) experienced by users after adjustingdegree of time-compression. We report results of user studiesshowing impact of these factors on the average- compression-rateachieved. We also present data on the usage patterns and benefitsof time compression. Overall, we show significant time-savings forusers and that considerable flexibility is available to thedesigners of client-server streaming systems with timecompression.

Asynchronous Collaboration Around Multimedia Applied to On-Demand Education

Multimedia content is a central component of on-demand training and education delivered over the World Wide Web. Supporting asynchronous collaboration around educational multimedia is potentially a significant tool for delivering online educational content effectively. A multimedia annotation system tightly integrated with e-mail provides a powerful platform on which to base such functionality. In this paper we describe a series of studies of such a system. First, we built a prototype annotation system and refined it based on results of laboratory tests. We then extended the system to support asynchronous collaboration for on-demand training and studied its effectiveness in two corporate training courses, assessing student experience, instructor experience, and user interface appropriateness. Having identified possibilities for enhancing engagement and collaboration with the tool, we conducted another set of laboratory studies. Through this iterative process we are creating a platform and identifying processes for its use, which enable students and instructors to exploit the advantages of asynchronous education while compensating for the reduction in face-to-face interaction.

Distance learning through distributed collaborative video viewing

Previous research on Tutored Video Instruction (TVI) shows that learning is enhanced when small groups of students watch and discuss lecture videos together. Using specialized, high-end videoconferencing systems, these improved results have been shown to apply even when the students are in different locations (Distributed TVI, or DTVI). In this paper, we explore two issues in making DTVI-like scenarios widely supported at low cost. First, we explore design of a system that allows distributed individuals to collectively watch video using shared VCR controls such as play, pause, seek, stop. We show how such a system can be built on top of existing commercial technologies. Second, we explore the impact of four alternative discussion channels on student learning and interaction behavior. The four channels-text chat, audioconferencing, videoconferencing, and face-to-face-have differing infrastructure requirements and costs. Our lab studies show that while text chat does not work, there is no significant difference in discussion behavior and learning between audioconferencing and videoconferencing. While lab studies have their limitations and long-term field studies need to be done, the preliminary results point to a low-cost way for a DTVI-like model to be deployed widely in the very near future.

Comparing presentation summaries: slides vs. reading vs. listening

As more audio and video technical presentations go online, it becomes imperative to give users effective summarization and skimming tools so that they can find the presentation they want and browse through it quickly. In a previous study, we reported three automated methods for generating audio-video summaries and a user evaluation of those methods. An open question remained about how well various text/image only techniques will compare to the audio-video summarizations. This study attempts to fill that gap. This paper reports a user study that compares four possible ways of allowing a user to skim a presentation: 1) PowerPoint slides used by the speaker during the presentation, 2) the text transcript created by professional transcribers from the presentation, 3) the transcript with important points highlighted by the speaker, and 4) a audio-video summary created by the speaker. Results show that although some text-only conditions can match the audio-video summary, users have a marginal preference for audio-video (ANOVA f=3.067, p=0.087). Furthermore, different styles of slide-authoring (e.g., detailed vs. big-points only) can have a big impact on their effectiveness as summaries, raising a dilemma for some speakers in authoring for on-demand previewing versus that for live audiences.

Asynchronous collaboration around multimedia and its application to on-demand training

Multimedia content is a central component of on-demand training and education delivered over the World Wide Web. Supporting asynchronous collaboration around educational multimedia is a key requirement for making the online educational environment effective. A multimedia annotation system tightly integrated with email provides a powerful platform on which to base such functionality. Building on our earlier work with multimedia annotations, we present user interface and system extensions to support asynchronous collaboration for on-demand training. We report results from a study of the effectiveness of the system, including student experience, instructor experience, and user interface appropriateness. Overall, the student experience was positive: they appreciated the flexibility of on-demand delivery and benefited from the collaborative features.

Evolving use of a system for education at a distance

Networked computers increasingly support distributed, real-time audio and video presentations. Flatland is an extensible system that provides instructors and students a wide range of interaction capabilities [3]. We studied Flatland use over multi-session training courses. Even with prior coaching, participants required experience to understand and exploit the features. Effective design and use will require understanding the complex evolution of personal and social conventions for these new technologies.