Transmission Of Video Signals Research Articles

Broadcast quality video over IP

We consider the problem of designing systems for the transmission of video signals of the quality found in current television broadcasts, over high-speed segments of the public IP network. Our most important contribution is the definition of a network/coder interface for IP networks which gathers channel state information, and then sets parameters of the video coder to maximize the quality of the signal delivered to the receiver, while remaining fair to other data or video connections. This interface plays a role analogous to that of a Leaky Bucket controller, in that it specifies traffic shaping parameters which result in simultaneous good Quality-of-Service (QoS) for the source and good network performance. Since the network is not assumed to provide any form of QoS guarantee, fundamental to our construction is a hidden Markov model for the channel, based on which the interface solves a problem of optimal stochastic control, to decide how to configure the encoder. Other contributions are: a) modifications to the standard Internet transport protocol, to make it suitable for the transport of delay-constrained traffic and to gather channel state information, and b) the design of an error-resilient video coder. Experimental studies reveal that the proposed system is able to stream video signals of the quality of current TV-broadcasts, among hosts in wide-area networks connected to the experimental vBNS backbone.

Transmission and multiplexing of uncompressed video and ancillary signals over a new multimedia frame

This work discusses the design and implementation of a fibre based, low cost communication system for transmission of uncompressed digitised 10 bit video and ancillary signals. The paper details a newly devised multiplexing scheme with a special frame format. The frame developed allows expandability for the multichannel transmission of audio-video signals multiplexed with other types of data. The system can be easily reconfigured to operate with different video and audio sampling frequencies so as to produce serial bit rates suitable for various applications. Test results show the efficacy of the transfer mechanism developed for the multiplexing and transmission of high quality signals.

Natives on the Electronic Frontier

Natives on the Electronic Frontier

Efficient video transmission over correlated Nakagami fading channels for IS-95 CDMA systems

This paper deals with the problem of efficient transmission of video signals over generalized fading channels in direct sequence-spread spectrum (DS-SS) code division multiple access (CDMA) systems. We first propose a modified version of the H.263 video codec incorporating a selective forward error correction (FEC) coding scheme combined with a forced intra-frame update mechanism. The modified codec results in the improvement of the average video and frame-to-frame performance. We further consider a coherent DS-CDMA system for the forward link (base-to-mobile) in both single-cell and multiple-cell environment. We provide performance evaluation results by both analysis, employing the Gaussian approximation, and computer simulations, using Monte Carlo error counting techniques. By integrating the proposed video codec with a coherent DS-CDMA system based upon the IS-95 standard, we investigate the performance of the video transmission over frequency-selective, correlated Nakagami fading forward-link channels employing a RAKE receiver. To simulate the fading channel, we have implemented in software a correlated Nakagami fading simulator based upon the principle of superposition of complex partial waves, an approach which replicates the wave propagation process in actual physical situations. A variety of performance evaluation results, both in single-cell and multiple-cell environment, are presented for a different number of resolving paths, cell user capacity, signal propagation characteristics, as well as for the presence of channel estimation errors. Heuristic explanations and interpretations of the trend of the obtained results are also given.

Video signal transmission for IS-95 environment

A novel compression scheme for video sequences that is robust to fading errors in a spread spectrum environment is presented. A 3D coder has been designed in which the sequence was decomposed into spatio-temporal sub-bands and encoded using vector quantisation. Channel simulation shows good image reconstruction with a PSNR of 27 dB under the worst-case channel conditions of 18 dB.

Improved Performance of WDM Systems by Partitioned Dispersion Compensation

Optimized dispersion compensation schemes help to alleviate performance limitations imposed by nonlinear fiber effects on WDM systems. Commonly, precompensation and postcompensation are compared in view of signal distortions. In this paper, the impact of the dominant effects self-phase modulation (SPM), cross-phase modulation (XPM) and stimulated Raman scattering (SRS) is analyzed for a generalized approach comprising the already mentioned compensation schemes as special cases. Each of the identical link sections consists of a standard single-mode fiber (SSMF) and two dispersion compensating fibers (DCFs), which are placed ahead of and behind the transmission fiber. The fundamental issue is the appropriate choice of the length of the DCFs. In view of SRS, the postcompensation scheme turns out to yield best performance. In contrast, system impairment due to XPM is minimized if the dispersion to be compensated per section is split up on the two DCFs. In view of analog signals transmitted in an all-optical network, spectral characteristics of the distortions are investigated. A typical application is the transmission of video signals making use of subcarrier multiplexing (SCM). The results reveal how to reduce the distortions of a particular video channel.

A low power dissipation 0.4∼7 GHz transimpedance amplifier IC for SCM optical communication system

A low power dissipation and broadband transimpedance amplifier IC has been developed for sub-carrier multiplexing (SCM) optical communication systems such as a multi-channel video signal transmission system. A 0.25 μm pseudomorphic double-heterojunction modulation-doped FET (MODFET) is adopted for the IC to achieve the required bandwidth and noise performance. Specifically, transimpedance gain of 52 dBΩ with equivalent input noise current of 12 pA/√Hz has been obtained between 0.4–7 GHz. In order to minimize the group delay (GD) deviation, a peaking control technique is investigated. We also adopted the flip-chip bonding method to reduce the parasitic elements. As a result, group delay deviation of less than 30 ps has been obtained. A novel SrTiO 3 (STO) capacitor process technology is incorporated to realize low power dissipation. By using integrated STO capacitors for DC blocking, single power-supply voltage of 5 V and power dissipation of 300 mW are realized. This power dissipation is less than one half of that required by conventional transimpedance amplifiers.

A general AR-based technique for the generation of arbitrary gamma VBR video traffic in ATM networks

Modeling variable-bit-rate (VBR) video source traffic is a crucial issue to evaluate the end-to-end performance of transmitting video signals over asynchronous transfer mode (ATM) networks. Difficulties in source modeling arise from the fact that VBR video source traffic usually follows a gamma distribution with high correlation among adjacent data. Many researchers adopt autoregressive (AR) models driven by a Gaussian error process to account for such correlation. The problem is: due to the closure property of the Gaussian distribution, the traffic so generated is Gaussian rather than gamma. As a remedy, some researchers directly consider gamma AR models instead. Unfortunately, the trouble arises from the fact that the closure property does not apply to gamma distributions, and thus, the linear operation performed by an AR model fails to produce gamma traffic. In this paper, we present a new technique that is capable of generating gamma-distributed traffic with arbitrary correlation while retaining the computational efficiency of Gaussian AR models. The central idea is to decompose given gamma traffic into a linear combination of a number of /spl lambda//sup 2/(1) sequences, and each of these latter processes can be easily obtained from a Gaussian AR process through a simple nonlinear operation. Results based on actual video teleconference data are presented to verify the validity of the new algorithm.

Video Enforcement of High-Occupancy Vehicle Lanes: Field Test Results for I-30 in Dallas

A study was conducted to assess and test promising technologies for high-occupancy vehicle (HOV) lane enforcement. After a qualitative assessment of video, automatic vehicle identification, and infrared machine vision technologies, the study was suspended because no preferred infrared machine vision technology was available for testing. The study was resumed when a vendor demonstrated promising video technology. The HOV enforcement and review (HOVER) system was then developed for an operational test on the I-30 contraflow HOV lane in Dallas, Texas. The results of an independent evaluation by Texas Transportation Institute indicated that the HOVER system, in its current state, could support a program that mails HOV information to suspected violators. The study’s limited budget prevented several improvements that could expand the capabilities of the HOVER system. With several enhancements to the system (e.g., improved license plate recognition and “whitelist” license plate database), the HOVER system could be used to perform enforcement screening, in which a technician reviewing vehicle compartment images works with a downstream police officer. Significant enhancements to the system (e.g., high-quality video cameras and additional camera views, improved video signal transmission, and improved license plate capture and recognition) could enable its use for HOV ticket-by-mail programs, although enabling legislation for such programs does not currently exist in Texas. The author recommends implementation of these enhancements and further testing to determine future system potential.

Improvement in the Management of Cancer Patients: Digital Ultrasound Documentation

Background: Ultrasound and computed tomography (CT) as well as magnetic resonance imaging (MRI) are known to be sensitive imaging tools in the management of cancer patients. Ultrasound has disadvantages for the follow-up, since standardized documentation is lacking. Therefore, we investigatedcomputer-assisted digital ultrasound documentation in cancer patients. Patients and Methods: From November 1996 to December 1997 ultrasound examinations were performed on 774 patients (leukemias n = 204, malignant lymphomas n = 311, solid tumors n = 103, miscellaneous n = 156). Ultrasound pictures were transferred to a personal computer (PC) by video signal transmission. Results: A total of 1,925 ultrasound examinations were documented in 377 men and 397 women. The mean age was 50.3 years, with an SD of 16.7 (range 16–97) years. A median of 2.8 ultrasound examinations per patient was performed (range 1–16 examinations). A total number of 9,311 ultrasound pictures was archived on a hard disc. Archived ultrasound pictures were compared with live ultrasound pictures, improving the comparability and quality of ultrasound. Analogue video print documentation was not necessary. Conclusion: Computer-assisted documentation of ultrasound pictures improves the management of cancer patients.

A fast single-pass deterministic video deghoster for terrestrial transmitted video

A new simple method of obtaining the multipath channel distortion within a terrestrial transmitted video signal is presented. The method finds in isolation the VSB-filter-induced relative detected quadrature ghost amplitudes, which had previously been difficult. The method is based upon correlation of the received signal with a version of the PAL GCR standard signal which has been modified by the inherent quadrature forming filter spectrum of the receiver VSB filter. Results are presented from simulation and a hardware prototype solution.

Investigations on bit error performance for video over DAB

The digital audio broadcasting (DAB) system which was originally designed for high quality audio transmission to mobile receivers is investigated for transmission of compressed digital video and multimedia signals. The bit error performance is considered using various levels of error protection provided by the DAB system. As a result, a net bit rate of about 1.5 Mbit/s can be achieved. With additional error correction coding, a bit error ratio (BER) of less than 10/sup -10/ can be realized. This is the requirement for compressed video signals. The SNR per bit is below 16 dB. The results are demonstrated and compared using computer simulations of the complete system.

A METHODOLOGY FOR REDUNDANCY ASSIGNMENT IN PRIORITY ENCODING TRANSMISSION (PET) OVER ATM NETWORKS

A novel approach called priority encoding transmission (PET) was recently proposed to guarantee delivery of the highest-priority data and/or the timely recovery of real-time data in the transmission of multimedia information over lossy networks. PET allows different segments of a message to be assigned priority levels, resulting in encoding information with different amounts of redundancy; the receiver is then able to recover the information in priority order, based only on the number of packets received per message. In this paper we propose a methodology to determine the fractions of the packets sent that are needed at the receiver to meet the quality of service (QoS) loss requirements specified by the user. It allows mapping of the required segment loss probabilities on the corresponding parameters of the PET system. As a relevant case study, the proposed methodology has been applied to the transmission of MPEG video signals over an ATM network using PET. The relative numerical results are presented and discussed. © 1997 by John Wiley & Sons, Ltd.

Objective methods for assessment of video quality : state of the art

In digital television networks, where the bitrates used for the transmission of video signals are variable, the issue of quality of service is of great importance. The QoS parameter of concern in this paper is the quality of MPEG-2 compressed video. Objective video quality assessment methods that can be used for continuous picture quality monitoring of digital encoding equipment at the entrance of the DVB network will be surveyed, along with parameters that can be extracted and transmitted to other parts of the network. The main objective of the contribution is to give an overview of the possibilities that exist and the progress that has been made so far.

Low noise characteristics of an AM-VSB video signaltransmission using a PDFA pumped by InGaAs semiconductor lasers through fibreBragg gratings

The authors have demonstrated 15 dBm output Pr/sup 3+/ doped fluoride fibre amplifiers (PDFAs) pumped by two high-power, and wavelength stabilised, InGaAs semiconductor lasers and also the low noise characteristics of AM-VSB video signal transmission using a PDFA. The wavelength of the InGaAs pumping semiconductor lasers was locked through fibre Bragg gratings, resulting in a reduction of the white-line noise in a CATV experiment, which is caused by the mode-hopping of the pumping sources.

A statistical feedforward/fedback buffer control for the transmission of digital video signals compressed by DCT-based intrafield coding

A new buffer-control policy for intrafield coding of video signals is presented. This method employs two statistical bit rate predictors-feedback and feedforward. It uses a feedback predictor in stationary portions of an image sequence and a feedforward predictor at scene changes. It is shown that this buffer-control policy is reasonably simple to implement and can effectively control output bit rate even at scene changes.

Telemedicine in rural areas. Experience with medical desktop-conferencing via satellite.

Cooperation between physicians in hospitals in rural areas can be assisted by desktop-conferencing using a satellite link. For six weeks, medical desktop-conferencing was tested during daily clinical conferences between the Virchow-Klinikum, Berlin, and the Medical Academy, Wroclaw. The communications link was provided by the German Telekom satellite system MCS, which allowed temporary connections to be established on demand by manual dialling. Standard hardware and software were used for videoconferencing, as well as software for medical communication developed in the BERMED project. Digital data, such as computed tomography or magnetic resonance images, were transmitted by a digital data channel in parallel to the transmission of analogue video and audio signals. For conferences involving large groups of people, hardware modifications were required. These included the installation of a video projector, adaptation of the audio system with improved echo cancellation, and installation of extra microphones. Learning to use an unfamiliar communication medium proved to be uncomplicated for the participating physicians.

Low-noise and high-power Pr/sup 3+/-doped fluoride fiber amplifier

We have successfully developed a low-noise and high-power Pr/sup 3+/-doped fluoride amplifier (PDFA) module with a cascade configuration. The maximum signal gain and noise figure were 40.6 dB and 5 dB, respectively. An output power of 20.1 dBm was achieved at an input signal power of 0 dBm. We confirm that this PDFA module performs well from experimental results on its use in a 40 channel AM-VSB video signal transmission and a 10 Gbit/s digital transmission.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Low-noise Pr 3+ -doped fluoride fibre amplifier

The authors have constructed a Pr3+-doped fluoride amplifier (PDFA) module pumped by an Nd-YLF laser. The maximum signal gain and noise figure were 20 dB and 5 dB, respectively. An output power of 19.2 dBm was achieved at an input signal power of 11.0 dBm. It was confirmed that this PDFA module has low-noise characteristics from experimental results on its use in a subcarrier multiplexed multichannel AM-VSB video signal transmission.

Telecommunication Reform: The History and Conditions Leading to Political Action

No abstract available.