Peter Parnes

Characterizing User Access To Videos On The World Wide Web

Despite evidence of rising popularity of video on the web (or VOW), little is known about how users access video. However, such a characterization can greatly benefit the design of multimedia systems such as web video proxies and VOW servers. Hence, this paper presents an analysis of trace data obtained from an ongoing VOW experiment in Lulea University of Technology, Sweden. This experiment is unique as video material is distributed over a high bandwidth network allowing users to make access decisions without the network being a major factor. Our analysis revealed a number of interesting discoveries regarding user VOW access. For example, accesses display high temporal locality: several requests for the same video title often occur within a short time span. Accesses also exhibited spatial locality of reference whereby a small number of machines accounted for a large number of overall requests. Another finding was a browsing pattern where users preview the initial portion of a video to find out if they are interested. If they like it, they continue watching, otherwise they halt it. This pattern suggests that caching the first several minutes of video data should prove effective. Lastly, the analysis shows that, contrary to previous studies, ranking of video titles by popularity did not fit a Zipfian distribution.

Mobile instant messaging

We describe a mobile instant messaging system, MIM, designed for mobile environments. During the design of mobile applications, several new problems and possibilities have to be considered that do not exist with applications targeted at desktop PCs. One example of an application not designed for a mobile environment is the current, very popular, instant messaging, typified by systems such as ICQ, AIM and MSN Messenger. We describe why current systems are not suitable in a mobile environment, and present our architecture for a new system, MIM, and show various implementations for different mobile devices such as PDAs, wearable computers and mobile phones.

An architecture for location aware applications

The paper presents an architecture for location aware applications, where positioning sources such as GPS, WaveLAN and Bluetooth devices can be seamlessly interchanged or even combined to achieve a more accurate positioning service with a higher availability than a single positioning source could provide. The architecture also supports peer-to-peer communication to allow clients to interchange position information over a local wireless network such as Bluetooth or WaveLAN. This enables a user to use other users position sources if their clients are close enough. The position information can be used directly by an application or be combined with habitual and other contextual information to achieve more personalized applications. A generic positioning protocol for interchange of position information between position sources and client applications is introduced and different techniques for merging of position information are presented. The interfaces for an application to access the platform and the platform to communicate with positioning sources are also discussed. The paper finally touches on privacy issues and outlines a schema for handling positioning information by using contracts that are easily maintained and controlled by the user.

mStar: enabling collaborative applications on the Internet

Distributed, real-time multimedia applications on the Internet permit users to cooperate in new and more interesting ways for collaborative teamwork and net-based learning. The mStar environment features an agent-based architecture, implemented in Java, which preserves compatibility with the dominant Mbone paradigm for IP multicast. The shared software environment provides an integrated solution for generating, presenting, scoring, and editing media in collaborative applications. In particular, mStar supports developers in creating distributed, real-time multimedia software applications such as e-meetings. mStar enhances both distance education and collaborative teamwork by presenting a uniform user interface for real-time audio and video, shared whiteboard, char, voting, and distributed Web-based presentations. The system also supports on-demand recording and session playback.

Lightweight application level multicast tunnelling using mTunnel

This paper presents a system, named mTunnel, for application level tunnelling of IP-multicast traffic in a lightweight manner, where the end-user is responsible for deciding which MBone-sessions and which IP-multicast groups to tunnel. mTunnel is primarily designed for easy deployment and easy-to-manage tunnelling. Information about currently tunnelled sessions and control of mTunnel is provided through a Web-interface. To save bandwidth, tunnelled streams can be transcoded on the media level and traffic sent through the tunnel can be compressed by grouping several packets together and using statistical compression. The overall bandwidth reduction achieved, without modifying the media itself, has been measured to be between 5% and 14%, depending on the traffic and media type.

Wearable systems in nursing home care: prototyping experience

Productivity in nursing care is a major concern in all residential facilities, as is improving the quality of care. Pervasive computing offers great promise in this area. In this paper we discuss requirements analysis, multiphase prototyping, and effective use of commercial off-the-shelf technologies to improve communication and situation awareness in nursing teams. We developed a wearable prototype with only a person-month of development time, using existing electronic meeting technologies for its multimodal communication platform.

The mWeb presentation framework

Abstract This paper presents a framework for bringing the MBone and the World-Wide Web closer together by introducing real-time distribution of HTML-pages and synchronization of WWW-browsers. This framework will enable distributed presentations of WWW-material using the mWeb application. Distribution is done using two new protocols, Scalable Reliable Real-time Transport Protocol — SRRTP and Scalable Reliable File Distribution Protocol — SRFDP. Synchronization is achieved using the WebDesk Control Bus, which allows for scalable messaging in large groups of programs and hosts. This paper also presents how the mWeb application can be used for programmed presentations resulting in a television-like Web-TV. The mWeb framework also includes support for creating HTML-slides and the usage of semantic remote-pointers.

Application-layer mobility support for streaming real-time media

This paper presents an UDP-based socket extension called the resilient mobile socket (RMS), which provides application-layer mobility support by encapsulating other sockets into a new aggregated socket abstraction. Encapsulated sockets can then be added or removed without disturbing running applications. RMS also provides a method for soft handovers where several encapsulated sockets are used simultaneously during a handover. As a proof of concept, a working prototype has been built by integrating RMS with Marratech Pro, a commercially available e-meeting application. This prototype has been used to evaluate RMS and to investigate how GSM audio quality is affected by handovers. The result from the investigation shows that soft handovers can be executed without loosing packets or causing extra latency, while a hard handover in average took around 200 ms to complete. This indicates that proactive handovers and redundancy are important, but that more work must he done to predict disconnections.

Location privacy in the Alipes platform

An increasing number of systems use contextual information about their users. Such contextual information can be used to design applications that survey usage and adapt thereafter, or simply just use context information to optimize presentation. Context information could therefore be used to create applications for the benefit of the users of the system, but the same information could cause serious violations of personal integrity if misused. Locality may be the most widely used, but also the most sensitive contextual information. The Alipes platform makes it easy to create location-based services while enforcing user privacy and integrity. The platform handles privacy through rules that describe how and under what circumstances a users context may be distributed to other users, for example rules describing limitations concerning the users context, a certain time period, the number of queries and the type of applications. This paper presents how location privacy is enforced in the Alipes platform.

A Study on Users’ Preference on Interruption When Using Wearable Computers and Head Mounted Displays

An important part of making a wearable computer unobtrusive is the user interface and the way it interrupts the user. The amount of interruption that have to be made on the users primary task should be minimized. Usage without interruption is of course best for the performance of the primary task but is often not possible as many tasks that the wearable computer is involved in do need interaction with the user. It is therefore important to understand what type of interruption that will benefit the user most. The question about which interruption that causes the least amount of stress for the user is as important as which interruption that gives the best performance. This paper continues on previous work where performance of the users was measured for different types of interruption. In this paper subjective data is analyzed to understand how to build user interfaces for wearable computers and head mounted displays that considers stress and other subjective variables