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Showing papers on "Video quality published in 1994"


Journal ArticleDOI
TL;DR: A full color video compression strategy, based on 3-D subband coding with camera pan compensation, to generate a single embedded bit stream supporting multiple decoder display formats and a wide, finely gradated range of bit rates is proposed.
Abstract: We propose a full color video compression strategy, based on 3-D subband coding with camera pan compensation, to generate a single embedded bit stream supporting multiple decoder display formats and a wide, finely gradated range of bit rates. An experimental implementation of our algorithm produces a single bit stream, from which suitable subsets are extracted to be compatible with many decoder frame sizes and frame rates and to satisfy transmission bandwidth constraints ranging from several tens of kilobits per second to several megabits per second. Reconstructed video quality from any of these bit stream subsets is often found to exceed that obtained from an MPEG-1 implementation, operated with equivalent bit rate constraints, in both perceptual quality and mean squared error. In addition, when restricted to 2-D, the algorithm produces some of the best results available in still image compression. >

688 citations


Journal ArticleDOI
TL;DR: This paper proposes to model a single video source as a Markov renewal process whose states represent different bit rates, and proposes two novel goodness-of-fit metrics which are directly related to the specific performance aspects that the model wants to predict.
Abstract: Models for predicting the performance of multiplexed variable bit rate video sources are important for engineering a network. However, models of a single source are also important for parameter negotiations and call admittance algorithms. In this paper we propose to model a single video source as a Markov renewal process whose states represent different bit rates. We also propose two novel goodness-of-fit metrics which are directly related to the specific performance aspects that we want to predict from the model. The first is a leaky bucket contour plot which can be used to quantify the burstiness of any traffic type. The second measure applies only to video traffic and measures how well the model can predict the compressed video quality. >

134 citations


Patent
02 Sep 1994
TL;DR: In this paper, a multi-point visual communication system which includes an adaptive filter part for controlling a spatial frequency characteristic of a video signal, a filter selector for selecting a video quality to be transmitted from its own site on the basis of integrated requests received from sites, and a filter control for adaptively controlling a filter characteristic taking both of the video information quantity and situations of a telecommunication network into consideration, is presented.
Abstract: A multi-point visual communication system which includes an adaptive filter part for controlling a spatial frequency characteristic of a video signal, a filter selector for selecting a video quality to be transmitted from its own site on the basis of integrated requests received from sites, and a filter control for adaptively controlling a filter characteristic taking both of a video information quantity and situations of a telecommunication network into consideration, and wherein a video signal processed by the adaptive filter part is subjected to an encoding operation and then transmitted to the telecommunication network. Thereby, the video quality can be selected according to users' requests, and the video quality of the multi-point visual communication can be improved without incurring an excessive increase of a video information quantity. Further, through the video signal processing taking both the video characteristic and the telecommunication network situations into consideration, a comparatively high quality of video transmission can be realized when viewed from an information quantity.

49 citations


Journal ArticleDOI
01 Aug 1994
TL;DR: A multichannel joint rate control algorithm is described and its performance simulated for MPEG encoded video on broadcast satellite (DBS) application indicates significant capacity and/or quality gains over conventional CBR transmission methods.
Abstract: A method to transmit multiplexed digital video that potentially allows for video quality and capacity gains over conventional constant bit-rate (CBR) transmission is described. The method uses a joint rate control algorithm that regulates the encoders during buffer congestion periods using bandwidth re-allocation and source rate control. A multichannel joint rate control algorithm is described and its performance simulated for MPEG encoded video on broadcast satellite (DBS) application. Results indicate significant capacity and/or quality gains over conventional CBR transmission methods. >

45 citations


Proceedings ArticleDOI
13 Nov 1994
TL;DR: Scalable compressed data structures based on a layered substream abstraction are described, with simple, generic scaling operations, for both constant bit rate and constant distortion scaling criteria.
Abstract: We propose a class of scalable video compression algorithms, within which compression performance may be exchanged for end-to-end delay. Each of the algorithms in this class produces a highly scalable bit stream, from which subsets may be extracted for compatibility with a wide range of display frame sizes, frame rates and bit rate constraints. Moreover, with modest end-to-end delay, the reconstructed video quality associated with any of these subsets is often superior to that obtained using an implementation of the inherently non-scalable MPEG-1 compression standard, operated with equivalent resolution and bit rate constraints. We describe scalable compressed data structures based on a layered substream abstraction, with simple, generic scaling operations, for both constant bit rate and constant distortion scaling criteria. >

22 citations


Journal ArticleDOI
TL;DR: The characteristics used to evaluate video coding algorithms and rules for subjective quality evaluations are suggested and frame-differencing techniques for low-bandwidth systems are described.
Abstract: We analyze the characteristics used to evaluate video coding algorithms and suggest rules for subjective quality evaluations.We examine video playback tasks and describe frame-differencing techniques for low-bandwidth systems.

18 citations


Proceedings ArticleDOI
01 Apr 1994
TL;DR: A rate control algorithm for delivery of digital video traffic on local area networks that results on uniform video quality during normal traffic conditions and graceful degradation during periods of congestion is proposed.
Abstract: A rate control algorithm for delivery of digital video traffic on local area networks that results on uniform video quality during normal traffic conditions and graceful degradation during periods of congestion is proposed. The algorithm controls a dual rate-control-mode MPEG-2 encoder. This encoder operates in either variable bit-rate (VBR) or joint rate controlled VBR mode.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

14 citations


Proceedings ArticleDOI
02 May 1994
TL;DR: A full color video compression strategy, based on 3D subband coding with camera pan compensation, to generate a single embedded bit stream supporting multiple decoder display formats and a wide, finely gradated range of bit rates is proposed.
Abstract: We propose a full color video compression strategy, based on 3D subband coding with camera pan compensation, to generate a single embedded bit stream supporting multiple decoder display formats and a wide, finely gradated range of bit rates. An experimental implementation of our algorithm produces a single bit stream, from which suitable subsets are extracted to be compatible with many useful decoder frame sizes and frame rates and to satisfy transmission bandwidth constraints ranging from several tens of kilo-bits per second to several megabits per second. Reconstructed video quality from any of these bit stream subsets is often found to exceed that obtained from an MPEG-1 implementation, operated with equivalent bit rate constraints, in both perceptual quality and mean squared error. In addition, when restricted to two dimensions, the algorithm produces some of the best results available in still image compression.

8 citations


Proceedings ArticleDOI
19 Apr 1994
TL;DR: A full colour video compression strategy, based on 3-D subband coding with camera pan compensation, to generate a single, embedded, compressed bit stream supporting multiple decoder display formats and a wide, finely gradated range of bit rates is proposed.
Abstract: We propose a full colour video compression strategy, based on 3-D subband coding with camera pan compensation, to generate a single, embedded, compressed bit stream supporting multiple decoder display formats and a wide, finely gradated range of bit rates. An experimental implementation of our algorithm produces a single bit stream, from which suitable subsets are extracted to be compatible with many useful decoder frame sizes and frame rates and to satisfy transmission bandwidth constraints ranging from several tens of kilo-bits per second to several mega-bits per second. The reconstructed video quality from any of these bit stream subsets is often found to exceed that obtained from an MPEG-1 implementation, operated with equivalent bit rate constraints, in both perceptual quality and mean squared error. >

6 citations


Proceedings ArticleDOI
02 May 1994
TL;DR: This paper presents formulations of these measurements and describes the implementation of an automated system to capture and test digital video quality, using complex digital image processing techniques to analyze differences between source and processed video sequences.
Abstract: Conventional analog video test measurements are generally not adequate for digital video, especially compressed video. This is because digital video distortion and artifacts often are spatially and temporally discrete phenomena. Most analog measurements assume that errors are of a continuous, linear nature. The only alternative to data has been subjective testing. Formal subjective tests (e.g., CCIR 500) can provide reliable, relative measures of video quality. However, such testing is time-consuming and expensive. Objective testing methods are needed to provide efficient, repeatable measures of video quality. A further advantage of objective testing is that it can provide greater insights into the nature of impairments. Presently, no standardized objective measures exist for digital video. However, pioneering work has been done by NTIA, NASA, ACATS and others to quantify the quality of digital video codecs. We have implemented some of the published measurements and others of our own design on a low-cost workstation. These measures utilize complex digital image processing techniques to analyze differences between source and processed video sequences. This paper presents formulations of these measurements and describes our implementation of an automated system to capture and test digital video quality.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

5 citations


Proceedings ArticleDOI
19 Apr 1994
TL;DR: Simulation results demonstrate that this hybrid coding system provides a subjectively superior video quality than traditional DCT coding systems: the corona effect is significantly reduced and the visible difference is most noticeable at low bit rates.
Abstract: This paper proposes a hybrid DCT/quadtree coding technique to compress motion compensated difference (MCD) images for video conferencing applications. The hybrid scheme is developed primarily to eliminate the visually annoying "corona" effect caused by the traditional DCT coding of subimage blocks containing edge components. In this coding framework, the quadtree segmentation scheme is selected to compress edge blocks because of its ability to describe geometrical structures accurately. For quadtree coded blocks, each segmented subregion is represented by its associated sample mean, which is quantized and transmitted along with the segmentation pattern information to the receiver for reconstruction. The remaining subimage blocks are coded using the DCT. Simulation results demonstrate that this hybrid coding system provides a subjectively superior video quality than traditional DCT coding systems: the corona effect is significantly reduced and the visible difference is most noticeable at low bit rates. >

Proceedings ArticleDOI
02 May 1994
TL;DR: The characteristics used to evaluate software-only video codec algorithms, namely: image fidelity, bandwidth, bandwidth efficiency, ease-of-decoding, memory consumption, compression to decompression asymmetry, scalability, and delay are examined.
Abstract: Software-only video codecs can provide good playback performance in desktop computers with a 486 or 68040 CPU running at 33 MHz without special hardware assistance. Typically, playback of compressed video can be categorized into three tasks: the actual decoding of the video stream, color conversion, and the transfer of decoded video data from system RAM to video RAM. By current standards, good playback performance is the decoding and display of video streams of 320 by 240 (or larger) compressed frames at 15 (or greater) frames-per- second. Software-only video codecs have evolved by modifying and tailoring existing compression methodologies to suit video playback in desktop computers. In this paper we examine the characteristics used to evaluate software-only video codec algorithms, namely: image fidelity (i.e., image quality), bandwidth (i.e., compression) ease-of-decoding (i.e., playback performance), memory consumption, compression to decompression asymmetry, scalability, and delay. We discuss the tradeoffs among these variables and the compromises that can be made to achieve low numerical complexity for software-only playback. Frame- differencing approaches are described since software-only video codecs typically employ them to enhance playback performance. To complement other papers that appear in this session of the Proceedings, we review methods derived from binary pattern image coding since these methods are amenable for software-only playback. In particular, we introduce a novel approach called pixel distribution image coding.

02 Dec 1994
TL;DR: The metrics presented here can be used to assist in the selection of appropriate video test scenes for subjective and objective performance tests of digital video compression systems.
Abstract: Describes two objective measurements that can be used to quantify the spatial and temporal information content of a video test scene. Test scene coding difficulty (and hence video quality) often depend on the spatial and temporal information complexity of the source video. The metrics presented here can be used to assist in the selection of appropriate video test scenes for subjective and objective performance tests of digital video compression systems.

Proceedings ArticleDOI
H. Harasaki1, M. Yano1
01 May 1994
TL;DR: The experimental results show that the negative impact to video quality, i.e. increase of the average quantizer step size, of the solution is small, thus proving the effectiveness of the proposed method.
Abstract: This paper proposes an interleaved forward error correction method for variable bit rate (VBR) video coding and quantitatively evaluates the performance under a practical usage parameter control (UPC) environment using hardware experimental VBR video coder. The proposed method is to have a timeout mechanism in the ATM adaptation layer specification (AAL) that flushes an interleave matrix which is only partially filled. The timeout flush operation is only activated when a variable bit rate video coder does not generate enough amount of bit within a given time period due to an inactive scene. The interleaving delay can be upper bounded by choosing the timeout values. This approach does not require any modification to video coders, since the regulation of the maximum delay is supported solely as an AAL function. The experimental results show that the negative impact to video quality, i.e. increase of the average quantizer step size, of the solution is small, thus proving the effectiveness of the proposed method. >

Proceedings ArticleDOI
14 Nov 1994
TL;DR: Adaptive 2-layered coding, two-step detection, and a two- step recovery with macroblock-based error concealment are proposed to keep the picture quality high by compensating for cell loss in an H.261 framework.
Abstract: The paper to address the issue of cell loss and its consequent effect on video quality in an H.261 framework, and possible compensative measures. Adaptive 2-layered coding, two-step detection, and a two-step recovery with macroblock-based error concealment are proposed to keep the picture quality high by compensating for cell loss. The simulation performance of the proposed system, which includes DCT-based layered coding with temporal error concealment, is compared with 1-layered and fixed 2-layered coding techniques. It is shown that good resilience and SNR improvement can be achieved even at quite high error rates by this system in particular for video sequences with high activity content. >

Proceedings ArticleDOI
02 May 1994
TL;DR: In this paper, a hybrid DCT/Quadtree coding technique was proposed to compress motion compensated difference images for video conferencing applications to eliminate the visually annoying "corona" effect caused by the traditional DCT coding of subimage blocks containing edge components.
Abstract: This paper proposes a hybrid DCT/Quadtree coding technique to compress motion compensated difference images for video conferencing applications. The hybrid scheme is developed primarily to eliminate the visually annoying `corona' effect caused by the traditional DCT coding of subimage blocks containing edge components. In this coding framework, the quadtree segmentation scheme is selected to compress edge blocks because of its ability to describe geometrical structures accurately. For quadtree coded blocks, each segmented subregion is represented by its associated sample mean, which is quantized and transmitted along with the segmentation pattern information to the receiver for reconstruction. The remaining subimage blocks are coded using the DCT. Simulation results demonstrate that this hybrid coding system provides a subjectively superior video quality than traditional DCT coding systems: the corona effect is virtually eliminated and the visible difference is most noticeable at low bit rates.

Journal ArticleDOI
TL;DR: Three new techniques to improve the function and performance of digital video-on-demand systems are proposed : multiple readouts of video programs within a few seconds from a disk drive, variable-bit-rate video storage for consistent video quality and efficient multiple readout, and audio-and-video synchronization that is compatible with a variety of communication networks and video decoding speeds.
Abstract: Digital video-on-demand is becoming important, in conjunction with the digitazation of communications and advances in video compression techniques. This paper proposes three new techniques to improve the function and performance of digital video-on-demand systems : multiple readouts of video programs within a few seconds from a disk drive, variable-bit-rate video storage for consistent video quality and efficient multiple readouts, and audio-and-video synchronization that is compatible with a variety of communication networks and video decoding speeds. A new system architecture is also proposed to employ these techniques and video packet transmission. The feasibility of these techniques is experimentally verified. A response time of under one second is achieved from a program request to program initiation on a terminal. In addition, simultaneous access to a video storage server is possible from four terminals if the maximum video bit rate is 2.8 Mbps.

Proceedings ArticleDOI
14 Nov 1994
TL;DR: A new 3-D segmentation-based coding technique is proposed, which can transmit a reasonable quality of video through very low bit rate channel and is robust to intra frame coding such as scene changes and frame refreshments.
Abstract: A new 3-D segmentation-based coding technique is proposed, which can transmit a reasonable quality of video through very low bit rate channel. Also, its bit rate regulation is robust to intra frame coding such as scene changes and frame refreshments. Through the experiments, a visually acceptable video quality can be obtained at less than 64 kbps. >

17 Jan 1994
TL;DR: This contribution presents one minor correction to the recommended value for the fraction above threshold in contribution T1A1.5/93-152, a method for estimating the video delay uncertainty of the automated time alignment algorithm, and an improved motion spike detector that could be used for computing parameters p10 and p11 in T1
Abstract: Contribution T1A15/93-152 summarized the methods of measurement for objective video quality parameters based on the Sobel-filtered image and the motion difference image that were submitted prior to conducting the T1A1 subjective experiment (this experiment collected 625 mean opinion scores - ie, 25 test scenes passed through 25 different video transmission systems that ranged in bit rate from 64 kb/sec to 45 Mb/sec) This contribution presents (1) one minor correction to the recommended value for the fraction above threshold in contribution T1A15/93-152, and (2) a method for estimating the video delay uncertainty of the automated time alignment algorithm presented in section 3 of contribution T1A15/93-152 (non-zero video delay uncertainty may result when dynamic time warping, or variable video delay, is present in the video transmission system, or when there is a substantial number of dropped video frames), (3) a method for using this video delay uncertainty in the computation of the parameters presented in T1A15/93-152, and (4) an improved motion spike detector that could be used for computing parameters p10 and p11 in T1A15/93-152

Proceedings Article
11 Feb 1994
TL;DR: It is shown that better resilience and SNR improvement can be achieved by this layered coding system compared with a 1-layered system with the same detection and recovery mechanism in the decoder.
Abstract: It is the objective of this paper to examine layered coding as a means of compensating for cell loss and its consequent effect on video quality in a H261 framework Fixed 2-layered coding, two-step detection, and a two-step recovery with macro block-based temporal error concealment are proposed to keep picture quality high in the presence of cell loss In the first part of this paper it is shown that better resilience and SNR improvement can be achieved by this system compared with a 1-layered system with the same detection and recovery mechanism in the decoder In the second part, the sensitivity of the gain to the several parameters is investigated by simulation including cell loss rate ratio (CLRR), error burst length (BL), and quantisation factor (Q) The results show a relatively linear relationship between the gain and the cell loss rate ratio and higher gain with longer error burst length There also exists an optimum quantisation factor for 2-layered video coding in an ATM environment

Proceedings ArticleDOI
16 Sep 1994
TL;DR: The extraction step is based on morphological tools and the selection is performed according to explicit perceptual criteria and the results at very low bit-rates validate the use of perceptual factors in advanced second generation coding techniques.
Abstract: Small visual features are often meaningful for the subjective quality of the coded images in very-low bit-rate video systems. If some significant features of the original images are coded, large improvements in the perceived quality can be achieved at low cost. Perceptual factors must be taken into account in order to select only the most significant features for coding. Perceptual coding is the key issue in second generation video coding systems in order to reach the lowest bit-rates with acceptable quality. In this paper, some solutions are proposed for the extraction, selection and coding of small image features in video sequences. The extraction step is based on morphological tools and the selection is performed according to explicit perceptual criteria. The selected features are motion compensated and then coded with an efficient technique derived from the READ coding (2D run-length) taking references in the temporal dimension. The results at very low bit-rates validate the use of perceptual factors in advanced second generation coding techniques.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Book ChapterDOI
01 Jan 1994
TL;DR: The hardware implementation of a codec for HDTV with flexible bit rates between 34 and 68 Mbit/s is described, which is part of the FLASH-TV satellite transmission system for HD TV contribution, which adapts its user bit rate automatically to transmission conditions and/or scene complexity.
Abstract: This paper describes the hardware implementation of a codec for HDTV with flexible bit rates between 34 and 68 Mbit/s. This codec is part of the FLASH-TV satellite transmission system for HDTV contribution, which adapts its user bit rate automatically to transmission conditions and/or scene complexity. The HDTV codec implements an extension of the CCIR Recommendation 723 (motion compensated DCT) to low bit rate HDTV compression and flexible bit rate real time operation. In addition to the high video quality achieved by the compression algorithm, this HDTV coding system offers a wide range of services and interfacing possibilities. Furthermore, its architecture is designed to ensure compatibility between current and future generation of HDTV equipment. The system will be available for field trials by the end of 93. A short description of the FLASH TV system and of the modem used is also given in this paper.