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Conference on digital compression technologies and Systems for video Communications

作者： Bakhmutsky, M PHILIPS RES BRIARCLIFF MANORNY

ISBN: (纸本)0819423564

Implementing a high-performance variable length decoder (VLD) presents a major challenge in building an MPEG-2 compliant HDTV video decoder. The capability of the VLD to process macroblocks in real-time can save memory and simplify decoder architectures. For an MPEG-2 main profile, high level compliant HDTV video decoder, this means that the VLD must be able to decode macroblocks at rates exceeding 100 million code words per second. Partitioning the system on the VLD level increases decoder complexity and memory utilization. It is therefore desirable to conceive of a 'one-piece' VLD capable of performing the required operations economically and in real-time. The process of decoding entropy-encoded variable length bit streams is inherently serial in nature. In the VLD, the parallel processing of the bit stream located between the resynchronization points is therefore limited. A unique technique of high-speed parallel bit stream processing is described. This technique is based on a non-traditional two- word bit stream segmentation method optimized for high-speed word length decoding. Applied to the main body of the bit stream, it produces excellent performance results in both consumer and professional profiles of MPEG where decoder partitioning at the VLD level might otherwise be the norm.

关键词： variable length decoder video decoder VLD HDTV MPEG-2

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Three-dimensional compression of video sequences

Three-dimensional compression of video sequences

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作者： Niesen, Joseph William University of Southern California

学位级别：Ph.D.

The two-dimensional, still image compression standard JPEG was extended to three dimensions and used to compress test standard video sequences. The 3-D video compression algorithm was used to compress the black-and-white, digital video sequences 'football' and 'Claire'. For the SIF video sequence 'Claire', a compression ratio of 200 was achieved at a Peak Signal to Noise Ratio (PSNR) of 29 dB, and a compression ratio of 100 was achieved at a PSNR of 35 dB. Ohm has reported 200 times compression ratio for 3-D video compression for similar video sequences. Ohm's PSNR was 27 dB, which is 2 dB more distortion than that achieved in this research. Rate-distortion performance for 'Claire' and for the interlaced, NTSC video sequence 'football' were determined. Reconstructed pictures for each sequence are included in this thesis. The 3-D quantization matrix and the 3-D coefficient transmission order were motivated by the JPEG compression algorithm. The rate-distortion optimization and motion compensation algorithms extended MPEG-2 methods to three dimensions. The 3-D coefficient transmission order strongly effected the rate-distortion performance. Ordering by the increased probability of a coefficient equalling zero is the motive for JPEG's transmission order, and produced the best results. But the overhead required to transmit the transmission order strongly reduced the compression ratio. A nearly optimal transmission ordering was determined based on the root sum square of the temporal frequency and the horizontal spatial frequency. The rate-distortion performance of the nearly optimal transmission order was within 10% of the optimal order's performance. Ordering by spatio-temporal frequency, in the manner of JPEG, produced compression ratios approximately one-half of the nearly optimal transmission order. Poor energy compaction for the vertical spatial frequency coefficients caused the suboptimal performance when coefficient transmission order was based on increasing spati

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Performance analysis of a multi-video traffic communication network

Performance analysis of a multi-video traffic communication ...

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Conference on digital compression technologies and Systems for video Communications

作者： Cheung, RWL Liu, PKC HONG KONG POLYTECH UNIV HONG KONGHONG KONG

ISBN: (纸本)0819423564

In this paper, we investigate a method to find the cell loss probability versus different buffer size for different types of video traffic in a statistical multiplexer. The fluid- flow model has been used to estimate the average cell loss of the video phone traffic. This approach is good for video traffic whose mean and standard variance are small. Conversely, the mean and standard variance for video traffic such as CATV and Studio_TV are comparatively large when those of the video phone traffic are compared. The fluid- flow approach cannot be used in determining the average cell loss probabilities in the video traffic carrying high average mean value because of the unbalancing of the equation roots. Because a motion video source could be represented by a mixture of Gaussian densities and the sequence of coded bit rates can be modeled more accurately by an autoregressive process whose parameters vary in time according to the state of a discrete Markov chain. This implies that the bursty traffic source can be represented by a number of equally virtual sources with relatively small mean and small standard variance. The fluid-flow model works satisfactorily with this virtual source because of its appropriate mean and variance value. When the correlation relationship of these equal virtual sources are properly identified using the discrete-time Markov chain, the result generated by one virtual source can be used to predict the probabilities of total cell loss which could happen to a bursty traffic source. Same technique can be applied to other video traffic whose mean and variance values are comparatively large. Thus, the average cell loss probabilities against different buffer size in a heterogeneous traffic network can be determined.

关键词： video Autoregressive models Multiplexers Differential equations Motion models Picosecond phenomena Statistical analysis Statistical modeling Transition metals video processing

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Lessons learned on reliable transmission of real-time MPEG-2 streams over ATM

Lessons learned on reliable transmission of real-time MPEG-2...

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Conference on digital compression technologies and Systems for video Communications

作者： Basso, A Civanlar, MR Cash, GL AT&T BELL LABS SIGNAL PROC LABRESHOLMDELNJ 07733

ISBN: (纸本)0819423564

This paper describes a system that has been designed and built at AT&T Bell Labs for studying transmission of real- time MPEG-2 video over ATM networks for multi-cast applications. The set-up comprises a hardware real-time MPEG-2 video, audio and system encoder, an ATM network adaptation module for MPEG-2 transport over AAL-5, and ATM switch, a software system decoder and a hardware elementary stream decoder. The MPEG-2 transport stream has been characterized in terms of robustness to errors. This preliminary study showed the higher importance of the structural information of the stream (PES packet headers TS headers, sequence, picture headers, etc.) with respect to the coded video data (motion vectors, DCT coefficients, etc.). A brief study of the current MPEG-2 hardware decoding architectures allowed us to better understand the effects of bit-stream errors on the resulting video quality. In our experiments, while the loss of some structural data such as picture start codes led the hardware decoder to loose synchronization or to freeze, the loss of video data only affected the image quality. Furthermore the recovery times from a loss of synchronization were orders of magnitude higher than the recovery from some video data loss. An error-resilient real-time software transport stream decoder has been developed. In multiplex-wide operations (i.e. operations on the entire transport stream) it takes advantage of ring buffers and manages the timing information appropriately. In video-stream specific operations it uses resynchronization mechanisms at the picture level which exploit the redundancy of the PES and transport stream syntax. Furthermore time data transfers between the system decoder and the elementary stream decoder are employed. Experiments show that proper use of these methods can significantly improve the system performance.

关键词： video Photoemission spectroscopy Asynchronous transfer mode Image quality Computer programming Standards development video compression Image processing Image quality standards Multiplexing

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Medical image compression using block-based transform coding techniques

Medical image compression using block-based transform coding...

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Conference on digital compression technologies and Systems for video Communications

作者： DeNeve, P Philips, W VanOverloop, J Lemahieu, I STATE UNIV GHENT IBITECHMEDISIPELISB-9000 GHENTBELGIUM

ISBN: (纸本)0819423564

The JPEG lossy compression technique in medical imagery has several disadvantages (at higher compression ratios), mainly due to block-distortion. We therefore investigated two methods, the lapped orthogonal transform (LOT) and the DCT/DST coder, for the use on medical image data. These techniques are block-based but they reduce the block- distortion by spreading it out over the entire image. These compression techniques were applied on four different types of medical images (MRI image, x-ray image, angiogram and CT- scan). They were then compared with results from JPEG and variable block size DCT coders. At a first stage, we determined the optimal block size for each image and for each technique. It was found that for a specific image, the optimal block size was independent of the different transform coders. For the x-ray image, the CT-scan and the angiogram an optimal block size of 32 by 32 was found, while for the MRI image the optimal block size was 16 by 16. Afterwards, for all images the rate-distortion curves of the different techniques were calculated, using the optimal block size. The overall conclusion from our experiments is that the LOT is the best transform among the ones being investigated for compressing medical images of many different kinds. However, JPEG should be used for very high image qualities, as it then requires almost the same bit rate as the LOT and as it requires fewer computations than the LOT technique.

关键词： image compression lossy medical JPEG transform coding block-based

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video-on-demand services: Efficient transportation and decompression of variable bit rate video

Video-on-demand services: Efficient transportation and decom...

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作者： Feng, Wu-chi University of Michigan

学位级别：Ph.D.

digital video compression techniques, such as the Motion-JPEG and MPEG compression standards, greatly reduce the network and storage requirements for digital video. These techniques, however, result in variable-bit-rate video which make the efficient handling and decompression of the video difficult. In this dissertation, we examine how variable-bit-rate digital video affects the ability to efficiently transport and decompress these videos. We introduce two new bandwidth smoothing techniques that reduce the resource requirements for the transportation of compressed video across networks: the critical bandwidth allocation algorithm, which, given a fixed buffer size, creates a bandwidth plan for the continuous playback of video that (1) requires no prefetching of data, (2) has the minimum number of bandwidth increases, and (3) minimizes the peak bandwidth requirements, and the optimal bandwidth allocation algorithm, which minimizes the total number of bandwidth changes required for continuous video playback. The use of bandwidth smoothing techniques in video-on-demand services results in plans that are somewhat inflexible. To allow users to have VCR capabilities in bandwidth smoothing environments, we analyze the utility of buffered video for decreasing the required interactions with the server. This buffered video, the VCR-window, allows users to have VCR capabilities within a limited without changing the bandwidth allocation levels. For accesses that cannot be serviced through the smoothing buffer, we show how contingency channels can be used to quickly return users to their original bandwidth allocation plans. Software video decompression algorithms have poor cache utilizations because of the long time between accesses to temporal data. We examine two techniques for reducing cache misses for software video decompression, reducing the working-set size and using software prefetching. To reduce the working-set size, we introduce several techniques that re-order the de

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Image resizing and enhanced digital video compression

EDN

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EDN 1996年第1期41卷 145-&页

作者： Ngo, C Genesis Microchip Inc Markam Canada

The introduction of the digital-audio compact disc led to the establishment of a new standard in audio recording and reproduction quality. The wide and rapid acceptance of digital audio indicate a public demand for high-quality sound. At present, the industry is undergoing a similar transition from analog to digital in video. This change is being brought about by two vital technologies;digital image resizing and video compression. digital image resizing limits the bandwidth requirements, while video compression reduces the amount of video data for storage purposes. The two technologies are working together to make the transition to digital video possible.

关键词： Image processing

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Multiresolution transform and its application to video coding

Multiresolution transform and its application to video codin...

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digital compression technologies and Systems for video Communications

作者： Bonneau, Robert Columbia Univ. New York NY USA

ISBN: (纸本)0819423564

Traditional wavelet edge detection and encoding schemes preserve shape features of objects effectively at a variety of spatial scales and also allow an efficient means of image and video compression. However these schemes also remove texture from imagery and thus image reproduction quality suffers. Fractal encoding techniques on the other hand generate high compression ratios but tend to introduce blocky artifacts in imagery. Thus we describe a video encoding method that combines the shape preserving capability of wavelets with the compression qualities of fractal compression for a hybrid multiresolution technique that achieves high compression, selective and accurate feature preservation, and is computationally efficient.

关键词： Image coding

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Software-embedded data retrieval and error concealment scheme for MPEG-2 video sequences

Software-embedded data retrieval and error concealment schem...

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digital video compression: algorithms and technologies 1996

作者： Le Buhan, Corinne Swiss Federal Inst. of Technology Lausanne Ecublens Switz

ISBN: (纸本)0819420425

This paper considers the problem of data recovery and reconstruction in erroneous MPEG-2 video sequences. The basic resynchronization point in MPEG-2 video bitstream is the slice header, a slice usually denoting a full row of macroblocks. When an error occurs, the rest of the damaged slice is lost up to the next slice. In order to improve the efficiency of conventional error concealment schemes, we propose to exploit the error detection information to force the decoding of error-free bits immediately after a lost area, before reaching either the next resynchronization point or the next erroneous area. This early resynchronization is achieved by trying to decode variable length codes until some macroblocks are recognized. In order to retrieve differentially coded data such as DC coefficients and macroblocks positions, a specific algorithm has been designed which uses not only available AC coefficients and neighboring data, but also differential values decoded from the early-resynchronized bitstream. This algorithm has been embedded in an MPEG-2 software decoder, combined with classical spatial and temporal error concealment techniques to interpolate the remaining lost areas. Simulation results show that up to 70% of the lost macroblocks can be retrieved in an intraframe coded picture. This retrieval along with temporal propagation yields a gain of several dBs as well as a visual enhancement over the whole sequence.

关键词： video signal processing

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Method for matching compressed video to ATM networks

Method for matching compressed video to ATM networks

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Proceedings of the 1995 IEEE International Conference on Image Processing. Part 3 (of 3)

作者： Safranek, Robert J. Kalmanek, Charles R. Garg, Rahul AT&T Bell Lab Murray Hill United States

Over the last few years three technologies have reached the stage of maturation where then can become synergistic. These are wideband, high speed networking high quality video compression (MPEG-I and II), and high capacity affordable digital storage media. This paper addresses the interaction of these three technologies. In particular, it examines the problem of taking a compressed video data stream that is stored on a server, and transmitting it over an ATM channel which has a capacity smaller than that required by the data stream. The conventional approach to this problem would be to transcode by decoding the video data, and then re-encoding so as to meet the channel constraints. Currently this is not a cost effective solution since, while MPEG decoders are relatively inexpensive, encoders are not. Our approach to this problem is to partially decompress the video bitstream. Then, perform the transcoding in the quantized data domain. Finally, a valid bitstream is reassembled and transmitted. This approach has the advantage providing nearly identical quality as the traditional transcoding approach, at a fraction of the hardware cost.

关键词： Image compression

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