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5th IEEE Workshop on Multimedia Signal Processing (MMSP 2002)

作者： Franchi, N Fumagalli, M Lancini, R Politecn Milan CEFRIEL I-20133 Milan Italy

ISBN: (纸本)0780377133

This paper proposes a multiple description (MD) video coder, which uses motion-compensated predictions. We suggested a new algorithm of MD named Polyphase DownSampling that describes Intra and Inter frames. Results show that by using the coder scheme and the error environment like those suggested by 161 our MD algorithm improves the performance of the system both in coding efficiency and error-resilience. Moreover our MD coding approach allows the introduction of a multi level scalability. This last topic is the direction follows in the further research.

关键词： video coder multiple descriptions motion-compensated prediction H.263+

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Very low bit rate video coding using virtual SPIHT

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ELECTRONICS LETTERS 2001年第1期37卷 40-42页

作者： Khan, E Ghanbari, M Univ Essex Dept Elect Syst Engn Colchester CO4 3SQ Essex England

A virtual SPIHT (VSPIHT) technique that is based on the SPIHT and virtual zero-tree concepts is proposed. It combines virtually generated zero trees on the top of SPIHT's zero trees to reduce the effective number of zero trees. The simulation results show that the proposed video coder is more efficient compared to SPIHT based video coders, particularly at very low bit rates.

关键词： trees (mathematics) set partitioning in hierarchical trees VSPIHT algorithm Image and video coding video coder virtual SPIHT video signal processing very low bit rate video coding virtual zero-tree concept Combinatorial mathematics video coding decoding

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Scalable wavelet video coding using aliasing-reduced hierarchical motion compensation

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2000年第5期9卷 778-791页

作者： Yang, XG Ramchandran, K Hewlett Packard Labs Imaging Technol Dept Palo Alto CA 94304 USA Univ Calif Berkeley Dept Elect Engn & Comp Sci Berkeley CA 94720 USA

We describe a spatially scalable video coding framework in which motion correspondences between successive video frames are exploited in the wavelet transform domain. The basic motivation for our coder is that motion fields are typically smooth and, therefore, can be efficiently captured through a multiresolutional framework. A wavelet decomposition is applied to each video frame and the coefficients at each level are predicted from the coarser level through backward motion compensation. To remove the aliasing effects caused by downsampling in the transform, a special interpolation filter is designed with the weighted aliasing energy as part of the optimization goal, and motion estimation is carried out with lowpass filtering and interpolation in the estimation loop, Further, to achieve robust motion estimation against quantization noise, we propose a novel backward/forward hybrid motion compensation scheme, and a tree structured dynamic programming algorithm to optimize the backward/forward mode choices. A novel adaptive quantization scheme is applied to code the motion predicted residue wavelet coefficients. Experimental results reveal 0.3-2-dB increase in coded PSNR at low bit rates over the state-of-the-art H.263 standard with all enhancement modes enabled, and similar improvements over MPEG-2 at high bit rates, with a considerable improvement in subjective reconstruction quality, while simultaneously supporting a scalable representation.

关键词： .coders video coder image coding motion vectors previous frame wavelet coefficients aliasing problem

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A very low bit rate video coder based on vector quantization

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IEEE TRANSACTIONS ON IMAGE PROCESSING 1996年第2期5卷 263-273页

作者： CorteReal, L Alves, AP Departamento de Engenharia ElectrotCcnica e de Computadores Faculdade de Engenharia Universidade do Porto Porto Portugal

This work describes a video coder based on a hybrid DPCM-vector quantization algorithm that is suited for bit rates ranging from 8-16 kb/s, The proposed approach involves segmenting difference images into variable-size and variable-shape blocks and performing segmentation and motion compensation simultaneously, The purpose of obtaining motion vectors for variable-size and variable-shape blocks is to improve the quality of motion estimation, particularly in those areas where the edges of moving objects are situated, For the larger blocks, decimation takes place in order to simplify vector quantization, For very active blocks, which are always of small dimension, a specific vector quantizer has been applied, the fuzzy classified vector quantizer (FCVQ), The coding algorithm described displays good performance in the compression of test sequences at the rates of 8 and 16 kb/s;the signal-to-noise ratios obtained are good in both cases, The complexity of the coder implementation is comparable to that of conventional hybrid coders, while the decoder is much simpler in this proposal.

关键词： video coder motion estimation difference image ENcoder Vector quantization Motion compensation quantizer decoders motion vector VARIABLE SIZE

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On the computation of warping-based motion compensation in video sequence coding

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SIGNAL PROCESSING-IMAGE COMMUNICATION 1998年第2期13卷 155-160页

作者： Neri, A Colonnese, S Univ Rome 3 Dept Elect Engn I-00146 Rome Italy Fdn Ugo Bordoni I-00142 Rome Italy

The paper illustrates a method for affine warping-based motion compensation using the computing architecture of H263 advanced prediction (AP) mode, namely, changing the (constant) weighting matrices in the H263 AP algorithm. In particular, we analytically derive a realization of affine image prediction based on a regular mesh in presence of linear resampling. The work shows, by means of analytical derivation and simulation results, an intrinsic similarity relationship between the affine motion model and the H.263 advanced prediction technique. The analysis offers a rational basis to explain the performance of H.263 AP as a coarse approximation of affine prediction. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： affine prediction video coder H.263 advanced prediction motion compensation

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Hierarchical motion estimator (HME) for block-based video coders

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 1997年第4期43卷 1320-1330页

作者： Accame, M De Natale, FGB Giusto, DD Univ Genoa Dept Biophys & Elect Engn I-16145 Genoa Italy Univ Cagliari Dept Elect & Elect Engn I-09123 Cagliari Italy

A hierarchical block-based motion estimation strategy for video sequence coding is proposed, which allows to reduce both the computational load and the number of transmitted motion vectors, The estimation is performed by first computing a coarse motion field at the lowest resolution of a Gaussian pyramid and then propagating and refining it till the maximum resolution, Main innovations concern the adaptive vector propagation and updating strategy, which allow an efficient recovery from wrong estimates while maintaining a low computational load, The advantages of the proposed method are manifold: first, it is able to decrease the computation of even two orders magnitude for an equivalent compensation;second, it generates a lower number of motion vectors, resulting in a lower information rate;third, it produces a more homogeneous motion field, thus easing a successive segmentation.

关键词： video coder MMP12 gene Hierarchical Information rates motion vector Propagating

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Adaptive rate controlling for reliable video communication over wireless packet networks

Adaptive rate controlling for reliable video communication o...

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International Conference on Image Processing

作者： Rajugopal, GR Hafez, RHM Carleton Univ Ottawa Canada

ISBN: (纸本)0818681837

This paper investigates the adaptive dynamic rate controlled video transmission for robust video communication under packet wireless environment. The video coder comprises of wavelet transform (WT), multi-resolution motion estimation (MRME) and robust zero tree coder The robust zero tree coder is a modification of the basic coder proposed by Shapiro to adopt coefficient level partitioning so as to slice out erroneous parts at the receiver and use the rest effectively. The adaptive dynamic rate controlling is required to adapt the video communication to the channel conditions so as to provide higher channel protection when the channel is severe and, improve the source rate and provide better performance when the conditions are favorable. The system evaluation is carried our under narrowband and broadband channel conditions. Both objective and subjective results are shown at 64 Kbps.

关键词： video communications Packet switched networks rate control source rate ENcoder waterway protection video coder rate adaptive system evaluation video transmission Narrowband wireless

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Rate control feedback mechanism for packet video networks

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ELECTRONICS LETTERS 1996年第8期32卷 716-717页

作者： Sadka, AH Eryurtlu, F Kondoz, AM Centre for Satellite Engineering Research University of Surrey Guildford United Kingdom

The authors incorporate a newly proposed late control feedback mechanism (RCFM) in an H.263 video coder. RCFM adapts to network conditions to locally drop video packets and then discard corresponding macroblocks (MBs) from any further prediction process. The proposed RCFM regulates the output bitrate of an H.263 codec while keeping all encoder parameters fixed and maintaining a good QoS.

关键词： video coder codecs rate control Writers feedback mechanism Packet

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MPEG-2 video compression

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ELECTRONICS & COMMUNICATION ENGINEERING JOURNAL 1995年第6期7卷 257-264页

作者： Tudor, PN Res. & Dev. Dept. BBC Tadworth UK

MPEG-2 is an extension of the MPEG-1 international standard for digital compression of audio and video signals. MPEG-1 was designed to code progressively scanned video at bit rates up to about 1.5 Mbit/s for applications such as CD-i (compact disc interactive). MPEG-2 is directed at broadcast formats at higher data rates;it provides extra algorithmic 'tools' for efficiently coding interlaced video, supports a wide range of bit rates and provides for multichannel surround sound coding. This tutorial paper introduces the principles used for compressing video according to the MPEG-2 standard, outlines the general structure of a video coder and decoder, and describes the subsets ('profiles') of the toolkit and the sets of constraints on parameter values ('levels') defined to date.

关键词： video codec video decoder video coder Codecs, coders and decoders video codecs Codes video signal compression television standards bit rates interlaced video coding digital compression compact disc interactive audio coding MPEG-2 standard MPEG-2 video compression SNR profiles parameter values Optical information, image and video signal processing audio signal compression 1.5 Mbit/s algorithmic tools Radio and television broadcasting MPEG-1 international standard multichannel surround sound coding video coding CD-I progressively scanned video

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Chroma coding for video at very low bit rates

Chroma coding for video at very low bit rates

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International Conference on Image Processing

作者： Karam, L Podilchuk, C AT&T BELL LABS SIGNAL PROC RES DEPTMURRAY HILLNJ 07974

ISBN: (纸本)0780331222

Color pictures are usually compressed in a luminance-chrominance coordinate space. We consider the problem of encoding the chrominance information for very low bit rate video coding systems aimed at bit rates in the range 8 to 40 kbps. The challenge is that the chrominance components typically get less than 10 to 20% of the total very low bit rate allocated for the video data. We found that it is sufficient to encode the chrominance information at 1/8 of the luminance resolution in both the horizontal and vertical directions. While, for many of the previous coding methods, the compression is performed independently for the luminance and chrominance coordinates, we propose a coding scheme which exploits the coded luminance data in coding and retrieving the chrominance components. The proposed video coder is an improved extension of an existing luminance-only coder so that color motion video can be coded at very low bit rates under fixed frame and bit rate constraints. It is based on a hybrid waveform coding technique with an implicit model-based component. Very good results were obtained for head-and-shoulders sequences even with chroma rates of less than 7% of the total very low bit rate. In addition, subjective tests indicate that the coded chrominance information improves the visual perception of noisy image features.

关键词： chromatic information chrominance components coding luminance video data Chroma videotapes video coder fixed frames Noisy Image Chromaticity labeling scheme

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