Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio

Statistical characterisation and stochastic modelling of 1-layer variable bit rate H.261 video codec traffic

The Integrated Services Digital Network(ISDN) is under re-design to provide flexibility which will ensure efficient network utilisation in the provision of broadband services. The main broadband services envisaged for provision on the Broadband ISDN(B-ISDN) are : Videophone; Videoconferencing; Television and High Definition TV. The B-ISDN will be a packet switched network where the packets(cells) will be transferred by the Asynchronous Transfer Mode(ATM) concept. Unlike voice and data services, the impact video services will have on the BISDN is unknown and hence loss of information is difficult to predict. Present videophone terminals are based on the CCITT H.261 Video Coding standard hence the picture quality is variable because video codec traffic is transmitted at a constant rate. To maintain a constant quality picture the codec output data must be transmitted at a variable rate or alternatively, for constant rate video codecs extra information must be made available to achieve constant picture quality. This latter technique is 2- Layer video coding where the first layer transmits at a constant rate and the second layer at a variable rate. The ATM B-ISDN promises constant picture quality video services, therefore to achieve this aim the impact variable rate video sources will have on the network must be determined by network simulation, thus variable rate video source models must be derived. To statistically characterise and stochastically model 1-Layer VBR(Variable Bit Rate) H.261 Video Codec traffic, here a videophone sequence is analysed by two alternative strategies : Talk-Listen and Motion Level. This analysis also found that 2-Layer H.261 Video Codec traffic can be stochastically modelled via a 1-Layer VBR H.261 Video Codec traffic model. Numerous hierarchical stochastic models with the ability to capture the statistical characteristics of long video sequences, in particular the short-term and long-term autocorrelations, are presented. One such model was simulated and the resulting simulated traffic was analysed to confirm the advantage hierarchical stochastic models have over non-hierarchical stochastic models in modelling video source traffic

Routing and switching in teleconferencing networks.

Leung, Yiu-Wing.Thesis (Ph.D.)--Chinese University of Hong Kong, 1992.Includes bibliographical references (leaves 150-157).AcknowledgmentsAbstractChapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.2 --- Broadband Video Services --- p.1Chapter 1.3 --- Videoconference Services --- p.7Chapter 1.4 --- Videoconference Systems --- p.8Chapter 1.5 --- Chapter Summary and Thesis Organization --- p.18Chapter Chapter 2 --- Efficient Algorithms for Multiple Destinations Routing --- p.20Chapter 2.1 --- Background --- p.20Chapter 2.2 --- Integer Programming Formulation of the MDR Problem --- p.26Chapter 2.3 --- Heuristics for Multiple Destinations Routing --- p.27Chapter 2.4 --- Performance Comparisons --- p.40Chapter 2.5 --- Chapter Summary --- p.50Chapter Chapter 3 --- Connection Optimization for Two Types of Videoconferences --- p.51Chapter 3.1 --- Background --- p.51Chapter 3.2 --- The Videoconference Services --- p.52Chapter 3.3 --- Connection Optimization --- p.54Chapter 3.4 --- Performance Analysis --- p.62Chapter 3.5 --- Chapter Summary --- p.80Chapter Chapter 4 --- A TDM-based Multibus Packet Switch --- p.81Chapter 4.1 --- Background --- p.81Chapter 4.2 --- Architecture of the Multibus Switch --- p.89Chapter 4.3 --- Operation of the Multibus Switch --- p.93Chapter 4.4 --- Performance Analysis --- p.95Chapter 4.5 --- Numerical Results --- p.106Chapter 4.6 --- Discussions --- p.109Chapter 4.7 --- Chapter Summary --- p.113Chapter Chapter 5 --- A Modular Shared Media Video Switch --- p.114Chapter 5.1 --- System Architecture and Operation --- p.114Chapter 5.2 --- Slot Assignment for Point-to-Point Transmissions --- p.129Chapter 5.3 --- Slot Assignment for Point-to-Multipoint Transmissions --- p.132Chapter 5.4 --- Network Design Example --- p.136Chapter 5.5 --- Chapter Summary --- p.143Appendix --- p.144Chapter Chapter 6 --- Conclusions --- p.147References --- p.15

Low Cost Video For Distance Education

A distance education system has been designed for Nova Southeastern University (NSU) . The design was based on emerging low cost video technology. The report presented the design and summarizes existing distance education efforts and technologies. The design supported multimedia electronic classrooms, and enabled students to participate in multimedia classes using standard telephone networks. Results were presented in three areas: management, courseware, and, systems. In the area of management, the report recommended that the University separately establish, fund, and staff the distance education project. Supporting rationale was included. In the area of courseware, the importance of quality courseware was highlighted. It was found that the development of distance education courseware was difficult; nevertheless, quality courseware was the key to a successful distance education program. In the area of systems, component level designs were presented for a student system, a university host, and a support system. Networks connecting the systems were addressed. The student system was based on widely available multimedia systems. The host system supported up to sixteen participants in a single class. The support system was designed for the development of courseware and the support of future projects in distance education. The report included supporting Proof of Principle demonstrations. These demonstrations showed that low cost video systems had utility at speeds as low as 7. 2 kbps. They also showed that high quality student images were not crucial to the system. The report included three alternate implementation strategies. The initial capability could be operational in 1997. A multi-session, 2000 user system was projected for early in the next century

Future benefits and applications of intelligent on-board processing to VSAT services

The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified

A very low bit rate video coder decoder

Ankara : Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 1997.Thesis (Master's) -- Bilkent University, 1997.Includes bibliographical references leaves 81-85.Bostancı, Hakkı TunçM.S

Applications of satellite technology to broadband ISDN networks

Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about $190M whereas the second architecture would be about$250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization

Content-prioritised video coding for British Sign Language communication.

Video communication of British Sign Language (BSL) is important for remote interpersonal communication and for the equal provision of services for deaf people. However, the use of video telephony and video conferencing applications for BSL communication is limited by inadequate video quality. BSL is a highly structured, linguistically complete, natural language system that expresses vocabulary and grammar visually and spatially using a complex combination of facial expressions (such as eyebrow movements, eye blinks and mouth/lip shapes), hand gestures, body movements and finger-spelling that change in space and time. Accurate natural BSL communication places specific demands on visual media applications which must compress video image data for efficient transmission. Current video compression schemes apply methods to reduce statistical redundancy and perceptual irrelevance in video image data based on a general model of Human Visual System (HVS) sensitivities. This thesis presents novel video image coding methods developed to achieve the conflicting requirements for high image quality and efficient coding. Novel methods of prioritising visually important video image content for optimised video coding are developed to exploit the HVS spatial and temporal response mechanisms of BSL users (determined by Eye Movement Tracking) and the characteristics of BSL video image content. The methods implement an accurate model of HVS foveation, applied in the spatial and temporal domains, at the pre-processing stage of a current standard-based system (H.264). Comparison of the performance of the developed and standard coding systems, using methods of video quality evaluation developed for this thesis, demonstrates improved perceived quality at low bit rates. BSL users, broadcasters and service providers benefit from the perception of high quality video over a range of available transmission bandwidths. The research community benefits from a new approach to video coding optimisation and better understanding of the communication needs of deaf people

Semi-synchronous video for deaf telephony with an adapted synchronous codec

Magister Scientiae - MScCommunication tools such as text-based instant messaging, voice and video relay services, real-time video chat and mobile SMS and MMS have successfully been used among Deaf people. Several years of field research with a local Deaf community revealed that disadvantaged South African Deaf people preferred to communicate with both Deaf and hearing peers in South African Sign Language as opposed to text. Synchronous video chat and video relay services provided such opportunities. Both types of services are commonly available in developed regions, but not in developing countries like South Africa. This thesis reports on a workaround approach to design and develop an asynchronous video communication tool that adapted synchronous video codecs to store-and-forward video delivery. This novel asynchronous video tool provided high quality South African Sign Language video chat at the expense of some additional latency. Synchronous video codec adaptation consisted of comparing codecs, and choosing one to optimise in order to minimise latency and preserve video quality. Traditional quality of service metrics only addressed real-time video quality and related services. There was no such standard for asynchronous video communication. Therefore, we also enhanced traditional objective video quality metrics with subjective assessment metrics conducted with the local Deaf community.South Afric