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Scalable wavelet video coding using aliasing-reduced hierarchical motion compensation

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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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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Wavelet-based video coding with early-predicted zerotrees

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IET IMAGE PROCESSING 2007年第1期1卷 95-102页

作者： Khan, E. Ghanbari, M. Aligarh Muslim Univ Dept Elect Engn Aligarh Uttar Pradesh India Univ Essex Dept Elect Syst Engn Colchester CO4 3SQ Essex England

The coding efficiency of DCT-based standard video codecs is significantly improved by skipped macroblocks. A similar concept is proposed for zerotree-based wavelet video coders. In a pyramidal wavelet transforrn, the wavelet coefficients are linked through spatial orientation trees. For each transformed frame, a method is proposed to identify those trees that are likely to be zerotrees throughout the coding process at a given bit budget. These trees are called the early-predicted zerotrees. These trees are then excluded from the subsequent quantisation and encoding processes. The tree classification is based on average energy of coefficients in the tree. The proposed technique is general and can be applied to any zerotree-based coding algorithm, but it is more advantageous to improve the perfomance of those zerotree-based video coding algorithms that use longer trees, such as virtual set partitioning in hierarchical trees (V-SPIHT). Simulation results demonstrate that the proposed technique can improve the performance of V-SPIHT-based video coder by up to 0.5 dB (on average) and can reduce the computational complexity by up to 80% (i.e. five times faster), for various test video sequences.

关键词： video coder complexity classes Wavelet coefficients tree sort code efficiency video codecs set partitioning video coding

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Motion vector based error concealment algorithms for video decoder

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IEICE TRANSACTIONS ON COMMUNICATIONS 2004年第6期E87B卷 1648-1659页

作者： Chen, MJ Chen, CS Hsu, CT Department of Electrical Engineering National Dong-Hwa University Taiwan

Compressed video bitstream is sensitive to errors that may degrade the reconstructed images severely even the bit error rate is small. One approach to combat the impact of error is error concealment at the decoder without increasing the bit rate and changing the encoder. We propose motion vector based error concealment algorithms to recover the motion vector per pixel instead of that per block according to the relation of neighboring motion vectors. The displacement per pixel can be estimated more accurately by using the tendency of neighboring motion vectors. Besides, we use not only the relation among motion vectors, but also the pixels. The pixels of the error block are divided into different parts according to their consistency with neighboring blocks and the displacement at each pixel of these parts is interpolated by relative motion vectors. From simulation results, the proposed motion vector based methods provide better reconstruction quality for damaged images than other methods.

关键词： error concealment motion vector video coder video communication

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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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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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VERY-LOW BIT-RATE video CODING USING 3D SUBBAND APPROACH

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR video TECHNOLOGY 1994年第3期4卷 309-316页

作者： NGAN, KN CHOOI, WL MONASH UNIV DEPT ELECT & COMP SYST ENGNCLAYTONVIC 3168AUSTRALIA

A video coder for very low bit rate applications is designed and simulated. It employs subband analysis technique to first split the video signal into four temporal subbands, Motion detection is performed to classify the co-sited macroblocks of the subbands into temporal activity (TA) macroblocks or no temporal activity (NTA) macroblocks. Far the TA macroblocks, motion classification is carried out by further dividing the four temporal subbands into 16 spatiotemporal subbands. The base temporal subband (LL(t)) is coded using a H.261-like (European COST 211 ter SIM3) coder with the motion estimation replaced by a reduced-motion search algorithm. The higher temporal subbands (LH(t), HL(t), HHt) are vector-quantized. The NTA-macroblocks (except in the baseband) are not coded at all. Simulation results are presented at 9.6 kbits per second (kbps) at five frames per second (fps) for a typical videoconferencing sequence. Comparisons are made with results obtained by the SIM3 coder.

关键词： image coding image sequences motion estimation teleconferencing vector quantisation video signals 3D subband approach 9.6 kbit/s European COST 211 ter SIM3 H.261-like coder SIM3 coder motion classification motion detection reduced-motion search algorithm Teleconference video coder image coding Subbands subband image sequences video signals Motion detection Vector quantization motion estimation

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Power-Aware Multimedia: Concepts and Design Perspectives

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IEEE CIRCUITS AND SYSTEMS MAGAZINE 2007年第2期7卷 26-34页

作者： Lian, Chung-Jr Chien, Shao-Yi Lin, Chia-Ping Tseng, Po-Chih Chen, Liang-Gee Natl Taiwan Univ Grad Inst Elect Engn DSP IC Design Lab Taipei 10764 Taiwan Natl Taiwan Univ Dept Elect Engn Taipei 10764 Taiwan

Mobile multimedia is a rising trend. A mobile device is light, thin, and small, but it is expected to be very powerful to support increasing multimedia functions, such as photos capture and display, real-time video communications, and movies and TV watching. To support these high computing and high bandwidth operations on a mobile device with limited energy, the power-aware design concept is expected to be introduced for further power optimization. A power-aware system is not only a conventional low power design, but also a design that can adaptively adjust its power consumption to specific conditions, such as different battery status, signal content, user preferences, and operating environments. In this article, we focus on the introduction of power-aware concepts and considerations to the architecture design of a video coder, followed by discussions of exiting power aware Motion Estimation and Discrete Cosine Transform designs. Although these modules are dedicated architectures optimized for real-time processing, they can provide power scalability by embedding some reconfigurable points inside.

关键词： discrete cosine transforms low-power electronics mobile communication motion estimation multimedia communication video codecs discrete cosine transform low power design mobile multimedia power optimization power scalability power-aware video coder discrete cosine transforms video codecs mobile communication MULTI-MEDIA SYSTEM motion estimation low-power electronics Building design

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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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Design of a novel Architecture of 3-D Discrete Wavelet Transform for Image Processing through video Compression 3

Design of a novel Architecture of 3-D Discrete Wavelet Trans...

引用

3rd International Conference on Communications and Signal Processing (ICCSP)

作者： Challa, Komala Vani Krishna, Puram Vamshi Rao, Chintapanti Nageswar VV Coll Engn Dept Elect & Commun Engn Tisaiyenvillai Tamil Nadu India Siddhartha Inst Sci & Technol Dept Elect & Commun Engn Tirupati Andhra Pradesh India

ISBN: (纸本)9781479933587

This paper presents a low power and high speed 3D-DWT (three-dimensional discrete wavelet transform) architecture for image compression. With the recent expansion of multimedia applications and the need for delivering compressed bit streams over heterogeneous networks, scalability has become an important feature for video coders. The 3-D discrete wavelet transform provides a natural spatial resolution and frame rate scalability. Scalability is achieved in tern poral and spatial resolutions, as well as in quality. The advantages of this scheme when they are compared with those of existing ones are in terms of complexity, low power, high throughput, low latency and minimum storage requirement. The proposed architecture has been successfully implemented on Xilinx Spartan 3E series field-programmable gate array, suitable for real-time compression.

关键词： Discrete Wavelet Transform (DWT) Image Compression video coder VLSI Architecture

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