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AN AUDIO COMPRESSION SYSTEM USING MODIFIED transform coding AND DYNAMIC BIT ALLOCATION

IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 1993年第3期39卷 255-259页

作者： SUNG, YC YANG, JF Department of Electrical Engineering National Cheng Kung University Taiwan

In this paper, a new digital audio compression system based on the modified transform and dynamic bit allocations is introduced. The modified transformation is proposed for the time-frequency representations of signals and the dynamic bit allocations scheme is used to progressively quantize the transform coefficients according to the rate distortion theory. Computer simulation results show that this proposed system, which achieves high audio quality on the rate 4 bits per sample, possesses low computational complexity suitable for multimedia applications. This coding system can further be operated in case of variable bit rate to allow application specific ancillary data without drastic loss of signal quality.

关键词： Audio compression transform coding Bit rate Audio coding Bandwidth Time frequency analysis Rate distortion theory Computer simulation Computational complexity Multimedia systems

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PERFORMANCE EVALUATION FOR transform coding USING A NONSEPARABLE COVARIANCE MODEL

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IEEE TRANSACTIONS ON COMMUNICATIONS 1978年第2期26卷 310-312页

作者： NATARAJAN, TR AHMED, N KANSAS STATE UNIV DEPT ELECT ENGNMANHATTANKS 66506

Intraframe transform coding of pictures for the case of a nonseparable covariance model is considered. Performances of the Walsh-Hadamard, discrete cosine and Karhunen-Loeve transforms are compared based on the compaction of signal energy in the transform components, and, the degree of decorrelation of the data. The results demonstrate that the performances of the discrete cosine and Karhunen-Loéve transforms compare closely, as is the case with a separable covariance model. The corresponding performance of the Walsh-Hadamard transform is inferior.

关键词： transform coding Image edge detection Detectors Quantization Displays Equations Gray-scale Brightness Image processing Facsimile

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SPECTRAL ENTROPY-ACTIVITY CLASSIFICATION IN ADAPTIVE transform coding

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1992年第5期10卷 913-917页

作者： MESTER, R FRANKE, U DAIMLER BENZ AG W-7000 STUTTGARTGERMANY

Most adaptive transform coding systems are based on a classification of transform blocks into classes of different statistical properties. In this contribution, a two-dimensional feature space for block classification is proposed which discriminates reliably between blocks that require very different processing. In combination with a block "activity" measurement, the introduced "spectral entropy" feature offers the possibility to stabilize the reconstruction quality of transform coding systems for each processed block on a high level.

关键词： transform coding Degradation Adaptive systems Decoding Encoding Pattern recognition Energy measurement Image coding

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COMPARING ORTHONORMAL MATRICES FOR TWO-DIMENSIONAL IMAGE transform coding BY MEANS OF THE GAIN DISTORTION FUNCTION

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SIGNAL PROCESSING 1980年第1期2卷 67-70页

作者： MAUERSBERGER, W Institut für Elektrische Nachrichtentechnik RWTH Aachen West Germany

The gain distortion function is defined as a performance measure for the comparison of orthonormal transforms on the basis of the rate distortion theory. It estimates the number of bits per picture element that can be saved by transform coding. Gain distortion functions were computed for several transforms of the dimension 8 × 8. Zusammenfassung Die Gain-Distortion-Funktion ist als Gütekriterium zum Vergleich orthonormaler transformationen auf der Basis der Rate-Distortion-Theorie definiert. Sie gibt einen Schätzwer für die Anzahl von bits je Bildpunkt, die durch transformationskodierung eingespart werden können. Gain-Distortion-Funktionen werden für mehrere transformationen der Dimension 8 × 8 berechnet.

关键词： Image coding transform coding rate distortion theory

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PERFORMANCE OF transform coding FOR CARRIER CHROMINANCE SIGNALS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1984年第3期32卷 324-327页

作者： MURAKAMI, H YAMAMOTO, H KDD Laboratories Tokyo Japan

This paper describes the results of theoretical studies made on performance of various kinds of intrafield two-dimensional transform codings (Hadamard, cosine, and slant) for carrier chrominance signals, by introducing a new measure (transform coefficients of zero variance) for such coding performances. In addition, a comparative study of the performance of these transform codings is performed for different sampling frequencies (2f_{sc}, 3f_{sc}, 4f_{sc}) with the same transmission rate, taking into account the tradeoff between the number of bits assigned to a picture element at each sampling frequency and the autocorrelation between adjacent picture elements.

关键词： transform coding Autocorrelation Frequency Error correction Error correction codes Sampling methods Signal processing Signal Processing Society Communications Society Performance evaluation

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UNIFIED REPRESENTATION OF DIFFERENTIAL PULSE-CODE MODULATION (DPCM) AND transform coding SYSTEMS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1974年第5期CO22卷 692-696页

作者： HABIBI, A HERSHEL, RS UNIV SO CALIF DEPT ELECT ENGNLOS ANGELESCA 90007

We consider a transform coding system that uses a lower-triangular transformation to uncorrelate the data. Based on this transformation we propose a generalized differential pulse code modulation (DPCM) system and show that at high bit rates it performs almost as well as coding by the method of principal components (Karhunen-Loeve transformation). This study connects the transform coding system to the DPCM encoder by showing that the proposed system simplifies to a standard DPCM encoder for Markov data.

关键词： Pulse modulation Modulation coding transform coding Covariance matrix Vectors Signal generators Contracts Markov processes Bit rate Quantization

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FedTC: Enabling Communication-Efficient Federated Learning via transform coding

FedTC: Enabling Communication-Efficient Federated Learning v...

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IEEE Conference on Computer Communications (IEEE INFOCOM)

作者： Guan, Yixuan Liu, Xuefeng Niu, Jianwei Ren, Tao Beihang Univ State Key Lab Virtual Real Technol & Syst Sch Comp Sci & Engn Beijing Peoples R China Zhongguancun Lab Beijing Peoples R China Chinese Acad Sci State Key Lab Intelligent Game Inst Software Beijing Peoples R China Zhengzhou Univ Zhengzhou Univ Res Inst Ind Technol Sch Informat Engn Zhengzhou Peoples R China

ISBN: (纸本)9798350383515;9798350383508

Federated learning (FL) enables distributed training via periodically synchronizing model updates among participants. Communication overhead becomes a dominant constraint of FL since participating clients usually suffer from limited bandwidth. To tackle this issue, top-k based gradient compression techniques are broadly explored in FL context, manifesting powerful capabilities in reducing gradient volumes via picking significant entries. However, previous studies are primarily conducted on the raw gradients where massive spatial redundancies exist and positions of non-zero (top-k) entries vary greatly between gradients, which both impede the achievement of deeper compressions. Top-k may also degrade the performance of trained models due to biased gradient estimations. Targeting the above issues, we propose FedTC, a novel transform coding based compression framework. FedTC transforms gradients into a new domain with more compact energy distributions, which facilitates reducing spatial redundancies and biases in subsequent sparsification. Furthermore, non-zero entries across clients from different rounds become highly aligned in the transform domain, motivating us to partition the gradients into smaller entry blocks with various alignment levels to better exploit these alignments. Lastly, positions and values of non-zero entries are independently compressed in a block-wise manner with our customized designs, through which a higher compression ratio is achieved. Theoretical analysis and extensive experiments consistently demonstrate the effectiveness of our approach.

关键词： Federated Learning Communication Overhead Gradient Compression transform coding

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Optimal transform coding of Gaussian mixtures for joint classification/reconstruction

Optimal transform coding of Gaussian mixtures for joint clas...

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Data Compression Conference 2003 (DCC2003)

作者： Jana, S Moulin, P Univ Illinois Beckman Inst Coordinate Sci Lab Urbana IL 61801 USA

ISBN: (纸本)0769518966

In a variety of applications, classification systems operate on compressed signals. This paper explores the design of optimal transform coders optimizing a joint classification/reconstruction criterion, where classification accuracy is measured using the Chernoff bound on probability of misclassification and reconstruction quality is measured using mean-squared error (MSE) distortion. Under a high-rate assumption, we show local optimality properties of the Karhunen-Loeve transform (KLT) for a certain class of Gaussian mixtures under a joint classification/MSE measure, and derive analytical expressions for optimal bit-allocation. This generalizes classical optimality properties of the KLT for Gaussian sources under the MSE criterion.

关键词： Bit rate Compression algorithms Data compression Decorrelation Design optimization Distortion measurement Image coding Image reconstruction Karhunen-Loeve transforms transform coding

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On Interframe transform coding

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IEEE Transactions on Communications 1977年第11期25卷 1323-1329页

作者： Natarajan, T. Raj Texas Instruments Incorporated Dallas TX 75222 United States Department of Electrical Engineering Kansas State University Manhattan KS 66506 United States

This paper is concerned with interframe coding of monochrome pictures using 3-dimensional transforms. First, an algorithm which enables the vector processing of 3-dimensional arrays is derived. Next, this algorithm is used in an interframe transform coding experiment. Picture data (6 bits/pel) is processed in (4 × 4 × 4) blocks using the Walsh-Hadamard transform (WHT), and the discrete cosine transform (DCT). The corresponding reconstructed pictures (1 bit/pel) are included. Copyright © 1977 by The Institute of Electrical and Electronics Engineers, Inc.

关键词： transform coding Discrete transforms Discrete cosine transforms Charge coupled devices TV broadcasting Charge-coupled image sensors Error correction Error correction codes Instruments Degradation

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Orthonormal Matrix Codebook Design for Adaptive transform coding

Orthonormal Matrix Codebook Design for Adaptive Transform Co...

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Data Compression Conference (DCC)

作者： Boragolla, Rashmi Yahampath, Pradeepa Univ Manitoba Dept Elect & Comp Engn 75 Chancellors Circle Winnipeg MB R3T 5V6 Canada

ISBN: (纸本)9781665478939

We present a novel algorithm for designing a transform codebook for adaptive transform coding a non-stationary source, where the codebook contains a set of or-thonormal transform matrices. The non-stationary source is modeled by a block-wise (locally) stationary process so that all vectors in a given block can be coded using a single transform-matrix chosen from the codebook. The transform-matrix codebook is designed such that the mean-square error (MSE) of coding locally stationary blocks, averaged over the ensemble of blocks (AMSE) is minimized. First, a sequence of training vectors from the non-stationary source (such as blocks of pixels extracted from images) is segmented into locally stationary blocks of vectors. Our design algorithm starts with an initial codebook and iteratively updates the codebook for the training set, similar to the well-known generalized Lloyd algorithm for vector quantizer design. Each iteration consists of two steps: 1) the training set is partitioned into subsets by encoding the training set using the current transform codebook, and 2) the code-book is updated by computing a centroid transform-matrix for each subset. A major difference compared to the standard Lloyd algorithm however is the requirement to enforce an orthonormality constraint on the matrices in the codebook during the computation of centroids. This is accomplished by mapping the constrained problem in Euclidean space to an unconstrained problem on the Stiefel manifold. Gradient-descent on the Stiefel manifold is then used to compute the centroids. Essential to the implementation of manifold gradient-descent is an expression for the AMSE which is differentiable with respect to the transform matrix. Towards this end, we present two expressions whose matrix derivatives can be analytically obtained: 1) an approximate high-rate expression assuming Gaussian distributed source vectors, and 2) an exact finite-rate expression assuming Laplace distributed transform coefficients.

关键词： Training Manifolds Image segmentation Adaptation models transform coding transforms Mean square error methods

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