Showing papers on "Video quality published in 1992"

An all-ASIC implementation of a low bit-rate video codec

Abstract: After many years of intensive deliberation, an international low-bit-rate video coding standard, known as CCITT (International Telegraph and Telephone Consultative Committee) Recommendation H.261, has been completed. The H.261 covers a wide range of bit rates at p*64 kbs, where p=1, 2, . . ., 30. A great deal of real-time signal processing power is required to compress an NTSC or other similar video signals to these rates for transport and to reconstruct the original signal back for display. In order to demonstrate the video quality of the newly established standard and the feasibility of a cost-effective VLSI solution, a real-time video codec based on H.261 has been constructed using ASICs (application specific integrated circuits). A single-board research prototype consisting of 11 ASICs with an aggregate signal processing power of approximately two billion operations per second is presented. >

Forgiveness effect in subjective assessment of packet video

Abstract: Experimental results are reported of the subjective assessment of picture impairments due to cell loss in asynchronous transfer mode (ATM) networks. It is shown that the CCIR 5-grade impairment scaling method is suitable for the kind of impairment found in overload conditions. The results serve to quantify the ‘forgiveness’ effect, which influences the subjective quality of the decoded pictures. Some suggestions are made as to how this can be taken into consideration in packet video quality assessment.

System and method for video compression with artifact dispersion control

Abstract: Systems and methods that enable digital video compression techniques to manage and control artifact presence in each compressed frame of the video clip. Wherein specific embodiments are applicable to interframe and intraframe video compression methods and can be used in the compression of digital images and digital video clips. Other embodiments are employable in digital video compression and are applicable to interframe compression methods. A mechanism to increase the amount of video compression, while maintaining video quality that may otherwise be sacrificed with such increases in video compression, by threshold value management to accommodate the human eye's ability to more readily discern local image features or artifacts at central image locations or focused-upon areas, while tolerating, to a greater extent, artifacts dispersed elsewhere in the image.

Alternative technologies and delivery systems for broadband ISDN access

Abstract: Switched on-demand video is expected to become a major consumer of bandwidth. Two-way video offers televisting, tele-education, and telecommuting services, which together could represent a further substantial bandwidth demand. High-speed data services to provide the fiber distributed data interface (FDDI) between locations, or even operate a computer-aided design (CAD) terminal remotely from its local area network (LAN), are likely new applications for broadband integrated services digital networks (B-ISDN). The video quality evolution and digital modulation techniques that are making broadband digital delivery of TV signals possible are reviewed. Cable TV B-ISDN delivery, short twisted pair B-ISDN delivery, and TV broadcast digital delivery are discussed. >

The development and evaluation of an objective video quality assessment system that emulates human viewing panels

Abstract: Discusses the approach used and the research conducted to develop an objective video quality assessment system that emulates human perception. The system returns results that agree closely with quality judgments made by a large panel of viewers for the subjectively rated video data set that was examined. This data set included 36 test scenes with widely varying amounts of spatial and temporal information and 27 impairments including digital video compression systems operating at line rates from 56 kbs/sec to 45 Mbs/sec with controlled error rates, NTSC encode/decode cycles, VHS and S-VHS record/play cycles, and VHF transmission.

Modelling of Audio/Video Data

Abstract: Advances in data compression are creating new possibilities for applications combining digital audio and digital video. These applications, such as desktop authoring environments and educational or training programs, often require access to collections of audio/video material. This paper introduces audio/ video, or “AV”, databases and discusses the key problem of data modelling in the context of time-based media. Extensions needed for modelling basic audio/video structures and relationships are described. These extensions, which include temporal sequences, quality factors, derivation relationships and temporal composition, are applied to an existing audio/video data representation.

Videoarthroscopy: review and state of the art.

Abstract: Since the introduction of videoarthroscopy, there has been rapid technological advancement. The charged couple device (CCD) has become the standard small pickup unit for the present cameras. The video signal processing and transfer has been modified and improved. New Y/C or super VHS and red, green, blue (RGB) systems have been associated with improvements in monitors, video recorders, and video printers. Measurements of video quality such as resolution, signal-to-noise ratio, pixels, and contrast have been confusing to clinicians evaluating these new systems. Equipment compatibility and the weak-link theory is important to understand when selecting new equipment. This review article presents an update for the clinician who wants more information to differentiate among the new video arthroscopic systems.

Spatial and Temporal Information Measures for Video Quality

Abstract: Presents an overview of metrics that can be used to quantify the amount of spatial and temporal information in a video sequence. By applying the metrics to the input and output video, the amount of spatial and temporal information that is lost by the digital video transmission system can be obtained. The spatial metrics are based on the Fourier transform of the image and the temporal metrics are based on the motion difference image.

A network interface for real-time video services on a high-speed multimedia LAN

Abstract: The authors present a method to integrate the uncompressed real time video data into high-speed multimedia LAN. They use a buffer insertion ring twisted-pair LAN to transfer the data. The video data will be transferred 30 frames/sec to get good video quality. A priority control scheme will make most of the real time data served first. It guarantees that the transmission delay falls into a tolerable range. A real-time input-buffer control scheme will always remove the oldest packet(s) instead of using input buffer limit (IBL) flow control. The authors also develop a user interface to make the system easier to operate. The system's complexity is hidden by the user interface. >

CCITT H.261 compatible mixed bit rate coding of video for ATM networks

Abstract: A mixed bit rate (MBR) video coding method is presented for asynchronous transfer mode (ATM) networks which has communication compatibility between constant bit rate (CBR) video codecs and variable bit rate (VBR) codecs. In MBR video coding, essential information is encoded at a CBR by using a conventional CBR coding method such as H.261 and enhancement information is encoded at a VBR to attain constant image quality. To realize the MBR coding of video, the conventional embedded pulse code modulation (PCM) quantization is extended by applying the requantization method only to the least significant bit (LSB) of the quantizer output. In the EX-EMB PCM method, the most significant part and least significant part (MSP/LSP) separation of embedded PCM and an additional threshold for the requantizer are dynamically determined to attain a desired distortion. The MBR codec with EX-EMB PCM was evaluated by computer simulations. The simulation results showed that the proposed method was effective not only for improving video quality but also it prevented the degradations of image quality at the scene change by increasing the bit rate for the VBR channel. >

Remote driving with reduced bandwidth communication

Abstract: Oak Ridge National Laboratory has developed a real-time video transmission system for low bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black and white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports teleoperation of a high mobility multipurpose wheeled vehicle at speeds up to 15 mph on a moguled dirt track. Video compression is achieved by using Laplacian image pyramids and a combination of classical techniques. Certain subbands of the image pyramid are transmitted by using interframe differencing with a periodic refresh to aid in bandwidth reduction. Images are also foveated to concentrate image detail in a steerable region. The system supports dynamic video quality adjustments between frame rate, image detail, and foveation rate. A typical configuration for the system used during driving has a frame rate of 4 Hz, a compression per frame of 125:1, and a resulting latency of less than 1s.

Video coding using switched motion compensation and high-order entropy coding

Abstract: High quality video transport is a key to the successful offering of networked multimedia or entertainment video services, especially under stringent bandwidth limitations. Video coding techniques that improve visual quality are thus of much interest. This paper reports a video coding scheme designed to transmit high quality HDTV at about 15 Mbps, a CCIR standard video at about 4 Mbps, or the common intermediate format (CIF) video at about 1 Mbps. To improve the known art of video compression, two techniques were further explored. One reduces the temporal redundancy of the input information, essentially by using a switched motion compensation technique. The other takes further advantage of spatial correlations in lossless spatial coding, essentially by using high order entropy coding of the quantized symbols. Two representative motion compensation techniques, the conventional frame-based motion compensation and a new field-adjusted motion compensation (FAMC) currently being proposed at the MPEG2 committee, were analyzed and compared with the proposed switched motion compensation. Based on the mean square prediction error of four test sequences, the new scheme achieves a consistent gain, at twice the processing complexity of the conventional scheme but at only 5% the processing complexity of the FAMC. This forward directional prediction is especially suitable for low delay coding in interactive visual communications, even though it can also incorporate bi-directional prediction to improve performance. The high-order entropy coding technique explored in this paper gives 27% lower rate than conventional run-length/Huffman coding. The required number of high-order entropy code tables is reduced by 97% by our innovative code table reduction technique. Compared to the results we reported before, the required number of code tables is further reduced by about 40% by merging similar codebooks from different components of the video source. The combined scheme using the block-switched motion compensation and high-order entropy coding reduces the total rate by 25% compared with the compression scheme we tested before, and achieves a comparable very good visual quality.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Effect of Multiple Scenes on Objective Video Quality Assessment

Abstract: Presents objective to subjective correlation results when the scores from multiple video test scenes are averaged. It is shown that the prediction errors of the objective video quality model are reduced, yielding objective measurement results that more closely approximate the subjective viewing assessments.

Preliminary Results of One-Way Video Delay Measurement Algorithms

Abstract: Out-of-service measurements can be used to obtain a baseline video system delay. However, in many digital video systems, video delay is dynamic and dependent upon the scene content. This contribution describes an objective measure of video delay that can be made "in-service" and can thus track dynamic changes in the one-way video delay of a transmission channel. The metric correlates motion in the input and output video scene. A block diagram of a potential, real-time implementation is also given.

Objective Measures of Video Impairment: Analysis of 128 Scenes

Abstract: ATIS Committee T1 contribution to standards project “Analog Interface Performance Specifications for Digital Video Teleconferencing/Video Telephony Service and DS3 Television”

Light shield device

Abstract: PURPOSE:To shut off a video noise, etc., appearing on an ineffective screen and to improve video quality by shielding an area on an optical filter, corresponding to an ineffective screen area, from light when the ineffective screen area appears on the screen of a monitor device. CONSTITUTION:A driving control part 6 supplies a driving control signal to a liquid crystal driving circuit 5 according to the kind of a video signal decided by an ID detection part 7 to perform light transmission/shielding control over respective areas A, B, and C of the optical filter 4. Namely, when an output image is of cinema scope size and displayed only at the part on the CRT 3 corresponding to the areas B and C of the optical filter 4, the areas A and D are shielded from light and then video noise light, etc., which is generated possibly at the ineffective screen area part is cut off by the optical filter 44, so that the quality of the image is never spoiled. Further, the mechanism is simplified and the safety and reliability are improved as compared with a case wherein shutters are provided mechanically.

Optimum Er/sup 3+/-doped fiber amplifier design for optical AM video signal distribution systems

Abstract: An investigation into the transmission characteristics of erbium-doped fiber amplifiers for use in optical AM frequency division multiplexing (FDM) video distribution systems is reported. The output signal power and noise characteristics of erbium-doped fibers were measured for different fiber lengths and different pump powers. The experimental results confirm that there exists an optimum amplifier design which gives the maximum distribution number when the pump power and the required video quality are given. >