ISSN:1124-318X    

DOI:10.1002/ett.4460080403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460080404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460080405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper describes the architecture implemented in five different countries to validate, by means of tests carried out with expert users, a service architecture for the interactive retrieval of multimedia information. The service architecture definition (which corresponds to the DA VIC 1.0 Specifications) and all activities for the set‐up and running of the experiments, have been carried out within the RACE R2120 “Multimedia Audiovisual Retrieval Services” (MARS) project. A unique server and terminal architecture has been developed and put in operation at each site, while a combination of different public network solutions were used for the terminal access side. All national experiments made use of an ATM‐based transport network. The interconnections between the five countries were provided by the European ATM Pilot (EAP). The minimal testbed configuration implemented in each country consisted of one server and two terminals. After the integration and test phases, this configuration was extensively tested within the national environment to obtain the users' perception of the

ISSN:1124-318X    

DOI:10.1002/ett.4460080406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThe DIAMOND project (Domestic IBC Applications for Multimedia on Demand; IBC = Integrated Broadband Communications), sponsored by the EC (RACE R2105), had the objective of exploring and demonstrating the technical feasibility of providing Video On Demand (VOD) to the home, with an acceptable quality of service at an acceptable cost level. Within Philips, a Video Server (VS) and Set Top Box (STB) were developed, while Octacon developed a Service Gateway (SGW). The system was tested on both a public switched network using ADSL (Helsinki, Finland) and on a CATV network (Sligo, Ireland); both trials were of a small scale and free of charge. The purpose of this paper is to present an overview of the overall system as developed for the DIAMOND trials, together with user evaluation results from the Helsinki trial.

ISSN:1124-318X    

DOI:10.1002/ett.4460080407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper introduces the HD‐SAT project, describes its main characteristics as well as the results of the system demonstration which was performed jointly with the dTTb project, (digital terrestrial television broadcasting) during the Montreux International Television Exhibition in June, 1995. The HD‐SAT system exploits the 20 GHz frequency band as the basis of a complete broadcast system delivering very high quality High‐Definition TV (HDTV) services over a variety of media. The satellite segment implements graceful degradation to assure the required service continuity. MPEG‐2 transmultiplexing is performed at the cable head‐end to provide an optimised transport stream for the cable channel. Maximising compliance to MPEG‐2 standards for the picture coding and DVB standards for the transmission segments results in a system open to interworking with other media and other services. This was demonstrated at the Montreux event, where the HD‐SAT system was demonstrated over live satellite and standard cable networks, and where common HD‐SAT coding and receiver hardware was used for the dTTb terrestrial and cable transmission within the join

ISSN:1124-318X    

DOI:10.1002/ett.4460080408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper describes the architectures for the reception of Digital TV in SMATV systems as well as the RF performance of the typical SMATV channel. Based on theoretical analysis, simulation and measurements campaigns performed within the DIGISMATV RACE Project, this paper presents the Reference Channel Model of SMATV systems which characterises the channel behaviour as the typical echoes performance in the coaxial distribution network. This network characterisation has been a key tool for designing and testing equalisers to be used in the QAM IRD's intended for SMATV. The interactive possibilities of SMATV systems using low cost satellite terminals are also addressed in this paper. Thanks to the achievements of the DIGISMATV RACE project it can be concluded that SMATV networks are compatible and ready for the new era of digital TV.

ISSN:1124-318X    

DOI:10.1002/ett.4460080409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractWe describe progress on automating the construction of 3D geometric models from video sequences. The system we are developing allows a person to walk around a room with a video camera, and from the video sequence alone extract a 3D model of the room. The room can then be graphically rendered together with possible arrangements of previously modelled objects, e.g. CAD models of furniture. The system is designed to ease model acquisition for virtual reality and telepresence applications, however the approach also has application in model based image coding. The approach is based on recent work in computer vision where image primitives are extracted and matched through an image sequence. For example, the simultaneous estimation of epipolar geometry and image corner correspondences. The matching techniques are both robust (detecting and discarding mismatches) and fully automatic. No knowledge of the camera (e.g. its focal length) or motion is required. 3D structure is computed from the matched image primitives (corners, lines and texture). The structure is then triangulated and texture is mapped onto the triangles from intensities in the images. Experimental results are provided for a variety of scenes, including isolated objects acquired with a standard CCD camera, and outdoor scenes acquired with a hand‐held camcorde

ISSN:1124-318X    

DOI:10.1002/ett.4460080410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractProvision of wideband services up to the final user anywhere is a challenging task for terrestrial technologies unless the satellite is included as an essential system component. This objective is even more difficult to be met if at least a limited degree of user interactivity and mobility is required. Satellite multimedia applications will require wide bandwidths, high degree of flexibility on‐board and intelligence at terminal level. The combined use of Ka band (20‐30 GHz) and EHF (in the range 40‐45 GHz) can extend interactive multimedia and personal services to ubiquitous and mobile users. This paper discusses the main interactive multimedia services and applications that may be provided via satellite. Particularly, it describes a new project, the “SECOMS project”, that is under way in the framework of a programme of the European Union. The paper provides some indications on the main SECOMS assumptions and requirements, and system design

ISSN:1124-318X    

DOI:10.1002/ett.4460080411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper presents a taxonomy of dispersity routing schemes designed to provide fault‐tolerant realtime communication. Our model involves the provision of dispersity at the application level, rather than in the physical layer as in traditional uses of dispersity. We assume a connection oriented realtime communication service such as that provided by the Tenet Suite 1 or Asynchronous Transfer Mode (ATM) networks. We use the ideas of dispersity routing, redundancy, disjoint paths, and hot and cold standbys to design and classify a set of schemes that can provide a range of fault‐tolerant realtime services. The classification provides a convenient framework, which we use to discuss the properties of the schemes and to conduct simulation experiments. We compare the service provided and the costs of our schemes to other approaches to fault‐tolerant realtime communication, such as the Internet approach. We conclude that dispersity routing is a flexible approach to increasing the fault tolerance of realtime connections, which can provide a range of improvements in service with a corresponding range of

ISSN:1124-318X    

DOI:10.1002/ett.4460080412

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY