Showing papers on "Video quality published in 1988"

Computerized court reporting system

Abstract: A court reporting system for providing a simultaneous written and video record under the control of a single court reporter. A court reporter's keyboard stenographic accepts inputs from the reporter and provides a signal reflecting keystroke combinations input by the reporter. A system clock provides the current time and date. There is a memory for receiving and storing signal sequences reflecting keystroke combinations and a table for defining keystroke combinations as control strokes. A video camera provides a video signal reflecting a viewed scene and a microphone provides an audio signal reflecting verbal testimony. A recorder is connected to the video camera and the microphone for producing a recording of testimony in progress. Finally, ther is a control system connected to the above elements including logic for separating keystroke combinations into phonetic keystrokes and control keystrokes, for recording the phonetic keystrokes in the memory, for periodically obtaining the current time and date from the clock and appending it to the recording of the video and audio and the signal reflecting keystroke combinations stored in the memory. The system provides an alarm when the stroke rate is over a safe limit for accurate recording or when more than one person speaks. Synthesized messages place the system on and off the rocord. provision is made for flagging, searching and correcting questionable words and for reminding the reporter to do so. The system can place the video and stroke records in synchronization for review and confirmation. The preferred system adjusts camera position and zoom for better video quality.

Source modelling for packet video

Abstract: Fast packet switching or asynchronous time division (ATD) networks have been proposed for integrated-services broadband communication systems because diversified services can be offered using unified protocols. Variable-rate video-encoding techniques are usually used in these communication systems to maintain constant video quality and to take advantage of the flexible nature of the ATD network. Since the bit rate is no longer a constant, statistical models are developed to measure the characteristics of the bit-rate sequence. A first-order Markov representation is proposed to describe the probabilistic behavior of the coded video sources. Based on these models, the ATD network protocol can be designed and analyzed. A general model is proposed for the coded source rate, and several special cases of the general model for different applications are described. The related issues of video coding in ATD networks are also discussed. >

Bandwidth Reduction For The Transmission Of Sign Language Over Telephone Lines

Abstract: Bandwidth reduction for the transmission of sign language over telephone linesMansouria BoubekkerTufts University/New England Medical Center750 Washington Street, Boston, Massachusetts 02111ABSTRACTThis paper describes a system for the transmission of American Sign Language (ASL) over standard telephone lines. Videoquality digital images require a transmission bandwidth at least 4000 times wider than that allowable by the standard voicetelephone network. This study presents compression, segmentation and coding techniques that reduce the information contentof visual images while preserving the meaning of the transmitted message.The resulting processed information can be transmitted at digital rates within the range of the commercially available 9600baud modems. The simulated real -time animations of the decoded cartoon images used for the experimental data representASL and finger spelling with an intelligibility approximating 85 %. This result is within the range of the intelligibilityprovided by speech communication over telephone lines.1. INTRODUCTIONThe deaf individual is vastly isolated not only from the rest of the society but also from other members of the deafcommunity because of the difficulty to communicate at a distance. He or she can not benefit from the telephone network,widely and extensively used by the hearing society. Even special telephones with amplifiers, available to the hard of hearing,can not be used by profoundly deaf individuals. The primary form of communication used among individuals of the deafcommunity is American Sign Language. ASL is a visual /gestural language comparable to spoken languages in the sense thatit has its own structure, morphology and syntax[1,2,3]. However, it is an independent language that uses movements of thehands and arms as well as facial expressions instead of sounds.While different means of communication at a distance can be used by deaf individuals, they all present some majordrawbacks:- High resolution video telecommunication systems, the ideal means of communication for the transmission ofvisual images, are limited by the high video bandwidth requirement[4].- Video conferencing, provides a high quality means of communication for the deaf but its use is limited because ofits incompatibility with the actual public switched telephone network and its restriction to the immediate institu-tion[5].- Teletypewriters (TTY), the most common means of communication at a distance, for the deaf individual, limit thesystem by the slow rate of typed messages and the unnatural use of English as a mean of communication.An ideal telecommunication system for the deaf would be one that allows the transmission of visual images through the useof the switched telephone network. The transmission of visual images, rather than auditory signals using the standardtelephone system is difficult because of the large bandwidth requirement of a video quality image. However, digitaltransmission, through the use of commonly available modems, can be accomplished over audio telephone lines at a datarate of 9600 bits /s. A compression factor of at least 4000 is required for the transmission of visual images over digitalchannels.

Variable rate video transport in broadband packet networks

Abstract: Broadband packet networking techniques based on high speed electronics in lightwave technology promise the fully integrated network of the future. Among other features, broadband packet networks could provide an efficient transport capability for variable rate real-time video traffic. This requires a careful tradeoff between the network and terminal design complexity. In this paper, terminal and network designs alternatives are investigated for end-to-end variable rate video transport in a broadband packet network. In particular, two different types of transport for a single video connection are presented using a hierarchical video coding scheme. This would allow efficient bandwidth sharing and minimum degradation in video quality.

Packet video transmission over a broadband implicit token passing LAN

Abstract: Presents a quantitative approach to the design of packet video transport systems for shared-access, broadband media The proposed methodology is illustrated by focusing on the problem of supporting a high quality multipoint-to-multipoint compressed video service using a 200 Mb/s implicit token passing (ITP) fiber optic LAN (local area network) The authors develop accurate simulation models, driven by realistic broadcast-quality AST-DPCM (adaptive spatio-temporal differential pulse code modulation) compressed video sources, for the example ITP-LAN system The models developed are used to determine design tradeoffs among channel throughput, video quality, and the transport level and media access level protocol features and parameters implemented in the packet video network interface unit It is shown that with appropriate transport and channel access protocols, high efficiency of channel use can be achieved with reasonable buffering requirements, without the use of adaptive coding strategies >

Video signal multiplex recoder

Abstract: PURPOSE:To attain the decoding of a received video data by inter-multi-point communication with simple constitution without deteriorated video quality by applying time division processing to plural video coded data and outputting the result as a pattern. CONSTITUTION:A coded video data from plural points such as 4 points is received by coded data reception circuits 1a-1d and stored in reception buffer memories 2a-2d. Then the content of the memories 2a-2d via a changeover switch 11 is fed sequentially to a variable length decoding circuit 3, an adder circuit 4 and changeover switches 12, 13, and the content of the memories 2a-2d is subject to time division decoding by the differential processing with the data already decoded from frame memories 5a-5d and the result is multiplexed by a video memory 6. The processing node is installed in a network with simple constitution not required to provide lots of parallel similar decoding circuits through the time division processing, and it is not required to reduce and synthesize the decoded data, and the decoding and multiplex without deterioration of the video picture quality of the received video data by inter-multi-point communication are applied.

Transmission of FDM wideband data and video channels over a single-mode fibre using 1300 nm LED

Abstract: The transmission of two frequency-division-multiplexed full motion network quality video channels and one digital ISDN-H1 channel over a repeaterless single-mode fibre in excess of eleven kilometres using a LED operating at 1300 nm wavelength is demonstrated. Transmitted video quality, and bit error rate performance of the digital channel are reported. Experimental system components and procedures are described in detail.