Hypermedia, Multimedia and Conferencing

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In recent years there have been dramatic changes in the technology available for information handling and processing. The power of workstations has increased rapidly, to a point where functions which a few years ago would be performed by dedicated hardware are now performed in software. Image and video coding is one example of this. Networks have also significantly increased in performance. A few years ago rates of up to 2 megabits/second (Mbps) for wide area networks was the limit; today the national SuperJanet network provides some 34 Mbps links today with some 155 Mbps links promised in the coming year.

These changes have enabled an enormous change in working and communications practices. The 'Virtual Library' could soon become a reality, with access being provided to electronic libraries around the world via telecommunications links and workstations. The notion of publishing can change, in that any organisation can electronically publish any material it chooses. An example of this is to be found in the World Wide Web (WWW), which allows multimedia material (images, text, audio and video) to be published and with viewers like Mosaic for this 'web' of information to be browsed. The inclusion of facilities to link material both locally and remotely makes for a very powerful and exciting global information source. The department has been heavily involved in developing WWW facilities over the past year. Much still remains to be done, and future work will investigate effective tools for discovering information from this organic lattice.

The technological advances have allowed compressed audio and video to be transmitted over packet networks and to be delivered to modern workstations. With this comes the opportunity for collaborative working between people at different sites. Our recent work in this area has culminated in the European MICE programme, where regular multimedia conferences spanning several European countries take place. Not only do the participants have audio and video communications, they are also able to use computer-based tools such as shared whiteboards to support their discussions. Notwithstanding the success of this work, improvements to the user experience are still possible and work on improving speech quality and developing a better spatial audio image is essential. There is also a need to record and archive conferences. Within the department, considerable progress has been made recently in these areas.

Although high speed networks and technology exist, suitable network services to convey isochronous bitstreams such as video and to multicast that data to large numbers of recipients are still not ideal, and work on multicast, and video services over SMDS and ATM networks has been producing interesting results. Finally, we have built a local high speed ATM infrastructure in order to allow us to build realistic local experiments in these areas.

Hypermedia and Multimedia Systems World Wide Web Jon Crowcroft, Mark Handley and Gordon JolyThe World Wide Web has revolutionised the Internet. Until recently, all access to information resources had been through command line interfaces familiar to traditional computer users, but alien to the new breed of users. These have been bought up on point-and-click systems on Macs and PCs, that had broadened the appeal of computers as everyday tools.The department of Computer Science at UCL runs one of the most accessed WWW servers in Europe. The server supports departmental research project information dissemination. We provide all course syllabi, brochures, and in the case of our MSc DCNDS course, all course notes are on-line. We also provide searchable indices of our research notes abstracts. Lastly, we are the starting point for a UK guide to be distributed throughout the academic community's servers, the virtual length and breadth of the country.We have been actively helping a number of other sites, including the BBC and News International, with setting up WWW servers - in the case of the BBC, some of our undergraduates should be given full credit for their initiative and abilities in starting that enterprise.We have also devised a tool for generating tours of the web to enable experts to become cyber-cartographers, mapmakers of the new virtual world, and share their findings with novice users.Collaborative WorkingMetalevel Architectures for Flexible CSCW DesignPaul Dourish (supervised by Jon Crowcroft)Traditional toolkit construction techniques use abstraction barriers to separate offered functionality from implementation. Increasingly, however, designers of large, complex systems are finding that this model of abstraction is problematic; that information must be passed down from application to infrastructure, and that the traditional model of abstraction gets in the way. In operating systems, this has led to user-level involvement in system operations (such as Mach's External Pager); in network protocol design, it has led to concepts such as Application Layer Framing; and in programming languages, it has led to metaobject protocols.Prospero is a toolkit for the construction of distributed applications supporting cooperative work. Built around a metaobject protocol, it allows application developers access not only to base-level functionality - the components and behaviours from which collaborative applications are built - but also to meta-level components which control the internal structure and behaviour of the toolkit itself. Metacode allows programmers to specialise aspects of the toolkit for the needs of specific applications or application domains. On the one hand, this allows the toolkit to be applied more widely than would be the case with traditional abstraction mechanisms, as the application programmer is now free to revise internal implementation decisions which would limit the applicability of the toolkit; and on the other, it aids the readability and comprehensibility of application programs, by separating the code which specifies application behaviour from that which specifies how that behaviour is to be supported.The two main areas which Prospero addresses are collaborative data management and user interface linkage. Since a wide variety of application types are to be supported by this toolkit, the data management components must be highly adaptable and able to support a wide variety of interactional styles. A generic mechanism has been developed, based on the repeated divergence and resynchronisation of separate streams of activity within a data store; this is a general case mechanism which is highly scalable, and supports not only traditional "synchronous" and "asynchronous" applications, but also "multi-synchronous" applications involving parallel, disconnected working. Consistency management in this scheme is managed using a generic mechanism based on light-weight consistency guarantees, which excahnge promises of expected degrees of synchronisation for pre-hoc descriptions of expected interface activity. Consistency guarantees can be regarded as a generalisation of traditional locking mechanisms, but allow much more flexibility both generally for applications, and in particular for specific instances of collaborative activity.User interface linkage is managed by integrating user interface components with user data. Thus, the components of interfaces - be they explicit components such as scrollbars and radio-buttons, or implicit components such as view filters and presentational transformations - can be moved between private and public workspaces. In the private workspace, they are under the individual control of each user; in the public workspace, they are subject to the same data sharing mechanisms as application data, and thus are available to the group as a whole for collaborative management. The same flexible mechanisms which can be applied to collaborative data can then be applied to interface components, providing a wide range of interface linkage facilities.In addition to investigating both user and system issues in collaborative systems, then, Prospero provides a framework for exploring the application of open implementation and metalevel programming techniques to new application areas, and opens up the opportunity to create a form of technological design which respects both traditional system approaches and the insights of sociological investigations of the mechanisms underpinning collaborative activity. Distributed Multimedia Applications for Interworking between European and US Researchers (DIMAGIO)Roy Bennett, Mark Handley , Anne Hutton, Gordon Joly, Peter Kirstein, Angela Sasse and Steve WilburThe aim of DIMAGIO is to promote the use of advanced telematics services for improving cooperation between research and development institutions in Europe and the US. This has been achieved through a number of public showcase multimedia conferencing events with user groups who were previously unaware of the potential of such services. The conference participants were therefore to be from disciplines not normally associated with the use of leading-edge communications technology.After a survey and assessment of potential opportunities for such events in 1994, three events were selected: a medical workshop and launch of an arts charity programme. During the preparation for this event, a third event, a conference on distance education, was proposed and run on behalf of Hewlett-Packard. All conferences used tools piloted and supported by MICE to provide these conferences.1) Minimal Invasive Surgery WorkshopA two-day workshop on novel minimal invasive surgery techniques, attended by surgeons specialising this area, was held at the Middlesex Hospital in London on November 10th and 11th 1994. The workshop consisted of talks and a number of demonstrations, i.e. live operations. The workshop sessions were transmitted from the hospital. On the second day, surgeons attending in Gothenburg, Sweden, and in San Francisco demonstrated live operations which were watched by the workshop participants in London.2) Artaids LaunchThe Artaids project involves a number of reknowned artists, who agreed to donate a piece of electronic art to Crusaid, a UK Aids charity. These art pieces were to be used in a long-term project on cooperative art: they were made available on a World Wide Web server for anyone to view and retrieve. Artists and other people were encouraged to create new pieces of art from this starter collection, and return them to the Artaids server as a further donation for Crusaid. Artaids was launched with a through a multimedia conference on November 28th 1994 between London, Stuttgart, Stockholm, Sydney, Melbourne and San Francisco. The project will continue throughout 1995, culminating in a further conference on World Aids Day in which the art pieces submitted during the year will be commended.3) Hewlett-Packard European Conference on Distance EducationHewlett-Packard wished to document European progress in the area of distance education by holding a conference between some of the major European centres. This will be achieved through a conference between UCL, Oslo University, the Royal Technical Institute (Stockholm) and the Technical University of Berlin (TUB). Presentations will be made from those four sites, with further audiences at Hewlett-Packard sites in Bristol, UK, and Lyon, France being linked to the conference via ISDN lines, and Stuttgart via a high-speed connection to Berlin. The system will use ASCEND hardware to combine several ISDN B-channels for each multimedia stream. For medium quality multimedia, 6 B-channels (384 Kbps) will be used. The channel multiplexing will be at UCL, so that 5 6 channels or 7 4 channel communication can be supplied over a primary rate (30 channel) ISDN link. The ISDN links will be combined with the world Internet links used for other MICE purposes.Remote Language Teaching over NetworksVicky Hardman, Angela Sasse, with D. Dittner (UCL Language Centre), J. Buckett, I. Campbell, E. Matthews and T. Watson (Exeter University)The ReLaTe (Remote Language Teaching over Networks) project is a SuperJanet Applications Project funded by British Telecom in cooperation with the JISC initiative. Its aim is to demonstrate the feasibility of sharing language teaching resources using multimedia conferencing, and to explore the implications of such applications for the development of networks and workstation technology as well as the pedagogy of language teaching.The study of the requirements for supporting tutors and learners in a range of language learning scenarios (lectures, small group tutorials, one-to-one sessions between tutors, peer interaction between learners) is due to be completed by the end of 1994. Based on these requirements, a demonstrator system based on conferencing tools piloted by the MICE project will be implemented. Since language teaching requires prime quality audio, specific developments in this project will focus on providing improved speech coding schemes. Specific video functionality, such as partial updating of video images and zooming in on parts of the face will be explored. Protoypes of application-specific shared workspace facilities will be developed.The demonstrator system will be used to deliver language teaching in a field trial with tutors and learners from the Language Centres at UCL and Exeter University over the SuperJanet SMDS service. The results of this evaluation will form the basis of a system specification and guidelines for the development and use of such systems.International Research Seminars using Multimedia ConferencingRoy Bennett , Stuart Clayman, Gordon Joly, Angela Sasse and Dennis TimmInternational research seminars started in autumn 1993, and have continued in 1994 on a fortnightly basis. Talks in this series on topics in communications, networks, distributed systems, multimedia and collaborative working are usually given from conference rooms at MICE partner sites, with researchers attending from their desktop workstations or in their local conference rooms. Apart from audiences at MICE partner sites, remote participants from all over Europe, the US and Australia have been attending.The seminars have provided a valuable testing ground for the effectiveness and reliability of the conferencing tools and underlying network infrastructure. We now have guidelines for conditions under which it is possible to hold such events. If packet loss, for instance, is greater than 20%, it is almost impossible to understand the speaker, particularly if the language used is not the listener's native language. In such circumstances, video transmission may be stopped completely to conserve bandwidth for the audio. Remote seminars need careful preparation and monitoring. Material displayed on the shared whiteboard tool needs to conform to certain standards in order to be readable when projected from workstation screens in remote conference rooms. New skills are required to give a multicast lecture, so some prior instruction and practise is required.Teleconferencing TechnologyMultimedia Integrated Conferencing for European Reseachers: The MICE projectRoy Bennett, Stuart Clayman, Mark Handley, Anne Hutton, Vicky Hardman, Gordon Joly, Peter Kirstein and Angela Sasse The MICE project pilots multimedia conferencing technology to enable interworking between European researchers, and with their colleagues in the US and the rest of the world. UCL is the leading partner in a consortium of nine research and development institutions in Belgium, France, Germany, Norway, Sweden and the UK.Multimedia conferencing provides users with audio, video and shared workspace facilities. The facilities piloted by MICE are integrated because they can be used from desktop workstations or in conference rooms, allow interworking of hardware and software codecs, are available over packet-switched and circuit-switched networks (ISDN), and use both uni- and multicast technology.The first phase of the project had three overlapping phases: definition, trial and evaluation. In the second phase, the technical achievements of the first phase have been consolidated. The software conferencing tools piloted by MICE are available on all major Unix workstations (Sun, SGI, HP and DEC). Improved audio, video and shared workspace tools, and an integrated user interface have been designed and are currently being evaluated. Software developed by MICE and cooperating developers is now distributed and supported through a network of MICE National Support Centres. The series of International Research Seminars delivered through this technology is continuing. The user base for multimedia conferencing has been broadened through a series of international conferencing events with users and audiences from non-technical backgrounds. Current technical developments include:Defining and implementing a flexible, distributed model for conference management and control;Incorporating the use of multimedia servers in conferences;Providing security for private multimedia conferences;Measuring and modelling network traffic during conferences and adapting tools according to conditions;Migrating to high-speed networks such as ATM.Running MICE Technology over ISDN Stuart Clayman and Anne HuttonThis work has involved the specification and evaluation of end-user ISDN equipment for use within multimedia conferences. This has particular relevance to the remote education and learning field, where the infrastructure is similar to that of multimedia conferences. The work focuses on the interworking between Internet-based and ISDN-based conferences, and shows how both the Internet-based multicast multimedia conferencing environment and the ISDN based multimedia conferencing environment can be connected. At present, both of these are independent environments which use their own protocols and standards to allow conferees to interact.The primary scope of the evaluation has been the defintion and use of a gateway between the multicast environment and the ISDN environment. Both Basic Rate ISDN equipment, which is more common for end users, and Primary Rate equipment have been used.A Conference Management and Multiplexing Center (CMMC) is used to provide gateway an protocol conversion facilities. For ISDN users in particular, a CMMC provides a gateway into the Internet multipoint environment by doing both protocol conversion and format conversion of video, audio, and shared workspace, to allow ISDN users to interact directly with Internet users in the same multimedia conference.The different end-user equipment that may be used to send and receive video, audio, and shared workspace over ISDN to a multicast conference are:A codec connected to the ISDN network, possibly with workstation support;A codec connected to the ISDN network and a workstation connected to the ISDN network;A workstation connected to the ISDN network with codec support;A workstation connected to the ISDN network.All of these configuations have been tested using 1 or 2 Basic Rate channels, and further work will evaluate the use of 4-6 channels for end-user equipment. We also intend to introduce more CMMCs on the Internet to enable more ISDN users to join multicast conferences. Incorporating Multimedia Servers in ConferencesStuart Clayman, Mark Handley and Peter KirsteinCurrent work on integrating the facilities provided by multimedia servers, into conferences, has focused on recording, indexing, and playback of multimedia conferences.When recording, both the audio and video streams of a source need to be archived, with a possible requirement for stream synchronisation to aid playback. As some seminars only require a subset of the conferees to be recorded, the record mechanism allows a selection of the streams to be recorded. The retrieval of recorded material needs to be easy for users to access either for direct playback to the user or for inclusion in another session, such as another multimedia conference. Users of the multimedia server need to know which conferences have been recorded and are online for access in order to select streams for playback. To aid users in their selection, various indexing techniques are being developed.A system called the Video Conference Recorder (VCR) has been designed primarily to record and playback conferences multicast over the Internet. The main objectives of the Video Conference Recorder are to:Record multicast conference data whose source may be any of the conferees;Allow users to create their own edits of recorded material and to create their own presentations for playback;Supply a large repository of disc space which is accessible to any user who wants to record or playback multimedia data.This system is currently being implemented.Once video data has been recorded it is sometimes problematic to find relevant information and we are designing some indexing techniques that may be used to find information in continuous media such as video.This work is novel in that it uses digitized media which has been previously stored, rather than analogue media.VCR is aimed at users who require recording and playback facilities of conferences, and is not intended to be a video-on-demand service. Further work is aimed at designing tools required for analysis of the media streams and tools for post-processing the media streams to modify them into more managable forms.Improving Speech Quality In Multimedia Conferencing SystemsMark Handley , Vicky Hardman and Angela SasseAudio transmitted over packet networks suffers from packet loss. Since audio quality is the main factor by which users judge the quality of conferencing systems, we have been looking at a number of approaches for repairing speech when packets have been lost. At the decoder, lost blocks have to be replaced with a suitable 'fill-in' to maintain timer synchronisation between the encoder and decoder. At high loss rates, the techniques fail, and then the only way of providing intelligibile speech is to add redundancy to the packets.Our research has concentrated on using synthetic speech to provide redundancy. The redundancy is generated at the encoder, and transmitted in a later packet. This is only possible in packet networks, because the decoder has to add-in a delay to the received packets in order to smooth out the variations in packet arrival times. Consequently, if the main packet has been lost, the redundant version can be played out instead, albeit with reduced quality. Speech intelligibility tests (speech comprehension as well subjective assement of quality) have been carried out for various loss rates and packet sizes, using a large number of subjects. The results show that this technique is very suitable for very high loss rates (upto 50%), if the redundant version can be guaranteed to be received. Sound Localisation in Multimedia ConferencingStephen Hailes, Vicky Hardman, Angela Sasse, withC.-D. Schulz (Rechenzentrum der Universitaet Stuttgart)The quality of speech over a head-set in multimedia conferences is often impaired when several participants try to talk at the same time. Even when only one person is speaking at any one point in time, conversations are often distributed, with speakers changing rapidly, which makes it difficult to attribute statements to participants. Helping users to identify speakers and attributing statements correctly is an important improvement to the usability of conferencing systems. In our recent research work, we have adapted sound localisation techniques developed for virtual reality environments to give users the impression that the other conference participants are located at certain angles in the virtual space. We have experimented both with a stereo head-set effect, where the sound seems to be coming from different angles inside the listeners head, and proper sound localisation, where the sound appears to originate from outside the listener's head and at varying angles and distances from the listener. The results show that users are able to distinguish sounds coming from the simulated angles, and that idenfication of speakers can be proved in this way.Conference Management and Control: the Conference Control Channel ProtocolMark Handley, Isidor Kouvelas and Ian WakemanOver the past few years multicast-based conferencing applications have been developed and widely deployed on the Internet, e.g. through the pilot activities associate with the MICE project. These multimedia conferencing applications are distributed, requiring no centralised conference control or multiplexing facilities. However, although the media applications performing video and audio coding have been very successful, such conferences also need some form of conference control. This is needed for a number of reasons, including floor control, bandwidth management and media synchronisation.To perform such tasks in a distributed manner requires a new approach to conference control. IP multicast groups allow us to view an entire conference as if there were a control bus. To this end, we have designed and implemented the Conference Control Channel Protocol (CCCP) which provides an addressing and scoping scheme for a bus model of distributed conference control, and also lets this bus model be extended to non-homogeneous conferences involving non-multicast hosts.CCCP is a basic building block, allowing new control messages to be inserted onto the Control Channel in such a way that other applications can listen to them for informational purposes. It also provides enhanced reliability for messages where required. Application-specific protocols are then built on top of CCCP in such a way that if their distribution model can be changed according to the networks being used to implement CCCP without having to modify the applications control functionality.We currently have a basic implementation of a CCCP library. Future work will involve floor and session control tools using CCCP, and extensions of CCCP to make its distribution model cope with non-multicast participants. CCCP is being considered as a candidate within the music conference management group in the IETF.Communications TechnologyEnhancing Multicast for Multimedia ApplicationsRoy Bennett and Jon CrowcroftThe EMMA project is intended to enhance the multicast software in terms of scaling, resource management and regulation of use, and then to bring wide area multimedia communications to the higher education (HE) community. We intend to set up the UK-MBONE among higher education institutions, and to provide system and application software, and technical support.Multimedia communications is one of the key technologies for the future, and can bring substantial benefits to the HE community. However, the current multicast has to be enhanced before we can make wide area multimedia communications available for regular use.Throughout the year, we have helped a number of specific sites and organisations come onstream. Examples include the following:bringing up liason support groups in Edinburgh Univeristy and Glasgow University.helping specific application groups at UCL (Medical Physics), Hatfield University (Graphics), and Loughborough University (WWW).TITAN : Multimedia Coding and DecodingStephen Hailes, Nermeen Ismail and Steve Wilbur The main aim of the project is to investigate and report on some of the issues related to the provision of wide scale multimedia conferencing services within the UK academic community. This project is an extension of a previous work carried out by us during which the suitability of the JANET MK II network for the support of realtime multimedia traffic was investigated. The results of that work were very encouraging thus raising the interest to investigate further issues regarding multimedia conferencing services over SuperJanet and the possibilities of having a unified service that supports sites with access to high bandwidth networks (SuperJanet) as well as sites with access to lower bandwidth networks (Janet).The first phase of TITAN consisted of a state of the art survey of the current status of multimedia conferencing. As more processing power becomes available for end-user machines at lower prices, software encoding of video data becomes more feasible and attractive. A comparison between software-based conferencing systems (conferencing systems in which most of the main functions such as video/audio encoding are carried out using software implementation) versus hardware-based conferencing systems (conferencing systems in which most of the main functions such as video/audio encoding are carried out using hardware boards) was conducted. Interworking between these two types of systems was investigated and analysed. An evaluation of the processing power requirements for video encoding and decoding using both H.261 as well as MPEG II standards was carried out. The results of that is now publically available via both UKERNA as well as the UCL WWW server.The second phase of the project consists of a series of tests to be run over the SMDS part of the SuperJanet. The aim of these tests is to evaluate the SMDS performance with respect to real time multimedia traffic. Both real H.261 compressed video data as well as simulated data will be used in these tests. Parameters such as losses, delay and jitter imposed by the network under different loading patterns will be looked at. This will help determine the average number of concurrent streams that can be supported by the network as well as the typical values needed to set applications playout buffers to and hence the expected end to end delay. The same tests will be carried on the ATM part of the SuperJanet network, as well as measurements of the traffic patterns.The last phase of the project is to arrange for a multimedia conferencing demonstration that involves participants that have SuperJanet access as well as those with only Janet access. The main criteria that the demonstration will concentrate on is the ability to provide high quality video between different sites with different bandwidth access without having to degrade the quality to match that of the site with the least bandwidth capacity.Infrastructure and SupportMICE National Support CentresRoy Bennett, Gordon Joly and Angela SasseOne of the main objectives of the second phase of ESPRIT project MICE is to promote and support the use of selected multimedia conferencing software throughout Europe. In order to achieve this, MICE National Support Centres (MICE-NSC) have been established in the countries represented in the MICE project, and in Austria, the Czech Republic, Denmark, Italy, the Netherlands, and Portugal.There is a charter for MICE National Support Centres, stating that MICE-NSCs serve as a national point of contact for users of multimedia conferencing software available in the public domain. The UK MICE National Support Centre started at UCL, but national responsibility has been distributed, with Scotland now being supported from Edinburgh and Glasgow. MICE-NSCs cooperate closely with network providers (such as UKERNA in the UK) and developers of public-domain software all in Europe and all over the world.The national MICE-NSCs cooperate very closely to test, document, and distribute software conferencing tools, and to support international user groups. Reference documents describing hardware platforms and supported public domain software tools are published through WWW pages set up by MICE NSCs. Some MICE-NSCs also offer consultancy and training to commercial organisatons interested in using the technology, and provide gateways e.g. between packet-switched networks and ISDN and conference multiplexing and management facilities. (The URL MICE-NSC at UCL is http://www.cs.ucl.ac.uk/mice/mice-nsc/index.html)