An improved algorithm for fast motion estimation based on the block-matching algorithm is presented for use in a block-based video coding system. To achieve enhanced motion estimation performance, an adaptive search p...
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An improved algorithm for fast motion estimation based on the block-matching algorithm is presented for use in a block-based video coding system. To achieve enhanced motion estimation performance, an adaptive search pattern length for each iteration for the current macro-block is proposed. In addition, search points that must be checked are determined by means of directional information from the error surface, thus reducing intermediate searches. The proposed algorithm is tested with several sequences and excellent performance is verified.
Spatio-temporal encoding in transmit and receive modes is of major importance in the development of ultrasound imaging devices. Classically, the assumption of constant sound speed in the medium allows one to restrict ...
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Spatio-temporal encoding in transmit and receive modes is of major importance in the development of ultrasound imaging devices. Classically, the assumption of constant sound speed in the medium allows one to restrict the beamforming process to the application of a cylindrical time-delay law on the elements of a multiple-transducer array. Here is proposed an iterative time-reversal method capable of taking into account all the heterogeneities of the medium, concerning density, speed of sound, and absorption variations. It will be shown that this iterative focusing process converges toward a spatio-temporal inverse filter focusing, the first step of the process being a time-reversal focusing on the targeted point. This method can be seen as a calibration process and has been successfully applied to transskull focusing and intraplate echoes suppression. It is leading the way to promising applications such as high-resolution ultrasonic brain imaging and high-resolution focusing through complex reverberating media, in nondestructive testing and telecommunications. This work highlights the advantages of using spatio-temporal coding to focus through complex media. Such codes require the use of fully programmable, multichannel electronics to implement this technique in real time.
We introduce FreeLence, a novel and simple single-rate compression coder for triangle manifold meshes. Our method uses free valences and exploits geometric information for connectivity encoding. Furthermore, we introd...
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We introduce FreeLence, a novel and simple single-rate compression coder for triangle manifold meshes. Our method uses free valences and exploits geometric information for connectivity encoding. Furthermore, we introduce a novel linear prediction scheme for geometry compression of 3D meshes. Together these approaches yield a significant entropy reduction for mesh encoding with an average of 20-30% over leading single-rate region-growing coders, both for connectivity and geometry.
The problem of optimising the structure of the encoder/decoder pair in a discrete communication system, with an additive distortion measure, is formulated in terms of a quadratic programming (QP) problem. This new for...
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The problem of optimising the structure of the encoder/decoder pair in a discrete communication system, with an additive distortion measure, is formulated in terms of a quadratic programming (QP) problem. This new formulation benefits from the following special features: it optimises the joint effects of the source/channel coding on the end-to-end distortion;and the encoder and the decoder structures are not restricted to being the inverse of each other. A method which obtains an epsilon-minimiser approximation of an optimum point of a general QP problem is discussed. Some simulation results based on this method are also given.
Recently clock and data synchronisation issues have prompted a rethink of how data should be communicated within embedded microprocessor systems, leading to the development of early standards for serial transmission o...
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Recently clock and data synchronisation issues have prompted a rethink of how data should be communicated within embedded microprocessor systems, leading to the development of early standards for serial transmission of data using packets;these feature a symbol for delineating the end of a packet. Bounds are investigated on the potential advantage, in terms of extra data compression, if compression took place in conjunction with packetisation. The Shannon formula for a binary data source is re-derived, showing how the formula varies when compressing relatively small chunks of data into packets. Simulation results suggest that a non-trivial amount of extra compression can be obtained in this way, and that the advantage is greater for data with lower original entropy.
In this article a new coding scheme, complement block coding (CBC), is proposed to reduce the PAPR of OFDM signals. This method utilizes the complement bits that are added to the original information bits, which can e...
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In this article a new coding scheme, complement block coding (CBC), is proposed to reduce the PAPR of OFDM signals. This method utilizes the complement bits that are added to the original information bits, which can effectively reduce the PAPR of OFDM signals with random frame size N and the coding rate R <= (N - k)/N, where k is a positive integer and k <= N/2. The performance results obtained with CBC are given and compared with that of some well known schemes, such as simple block coding, modified simple block coding, simple odd parity code, and cyclic coding, for the same purpose. The results show that at the same coding rate 3/4, CBC can achieve almost the same performance as SBC and MSBC, but with lower complexity, and the same performance can be obtained with a higher coding rate using CBC. The PAPR reductions of CBC with coding rate (N - 1)IN are almost the same as with a coding rate less than (N - I)IN, but almost the twice as these of SOPC when N >= 16. Moreover, we can find that PAPR is the lowest for all block codes using CBC with coding rate 3/4. So modified CBC (MCBC) is also proposed and analyzed, combined with the subblock processing technique to make CBC effective for OFDM systems with large frame sizes. The flexibility in coding rate choice and low complexity make the proposed CBC more suitable for random frame size with high coding rate and can also provide error detection.
The advancements in channel coding theory over the past decades have been accomplished by considering of additive white Gaussian noise (AWGN) channels. Much less is known about the consequences when the standard AWGN ...
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The advancements in channel coding theory over the past decades have been accomplished by considering of additive white Gaussian noise (AWGN) channels. Much less is known about the consequences when the standard AWGN assumption is not fulfilled in realistic environments and, more importantly, the appropriate countermeasures. The paper investigates the robustness of turbo codes decoded by existing quadratic-type algorithms in heavy-tailed, non-Gaussian noise channels. It illustrates that impulsive noise constitutes a major impairment in turbo decoding by studying the a posteriori probabilities computed by the constituent decoders, in addition to a formal account in terms of error probability performance. It is found that the performance of turbo codes is extremely sensitive to the shape of the underlying noise density function, being considerably degraded when this function departs from Gaussianity into a heavy-tailed distribution. A robust variant of existing decoders for reliable decoding of turbo codes to heavy-tailed noise is proposed and studied. The robustness is achieved by the enforcement of a non-quadratic soft metric into the decoder for good estimation of the transition probabilities and reliable extraction of extrinsic information.
A number of approaches have been proposed for enhancing/extracting a given speech in a noisy environment, in the aim of, for example, enhancing the speech recognition rate. The speech enhancement can be carried out by...
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A number of approaches have been proposed for enhancing/extracting a given speech in a noisy environment, in the aim of, for example, enhancing the speech recognition rate. The speech enhancement can be carried out by either using single or multiple channel measurements. Some of those approaches explore the harmonicity of speech, and others make use of the redundancy among the channels, usually by independent component analysis. To enhance one speech from a single channel, we propose here to use the characteristics of speech through the concept of efficient coding, which mimics the way the auditory cortex code information. This is carried out in a supervized fashion. Simulations and real world measurements show that this technique can be used efficiently to enhance a given speech signal. (C) 2005 Elsevier B.V. All rights reserved.
Test access mechanism (TAM) optimisation and test data compression lead to a reduction in test data volume and testing time for SOCs. In this paper, we integrate for the first time both these approaches into a single ...
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Test access mechanism (TAM) optimisation and test data compression lead to a reduction in test data volume and testing time for SOCs. In this paper, we integrate for the first time both these approaches into a single test methodology. We show how an integrated test architecture based on TAMs and test data decoders can be designed. The proposed approach offers considerable savings in test resource requirements. Two case studies using the integrated test architecture are presented. Experimental results on test data volume reduction, savings in test application time and the low test pin overheads for a benchmark SOC demonstrate the effectiveness of this approach.
1. Moving beyond today's silicon integrated chip technology will requireshrinking logic and memory circuits to the scale of a few nanometers. Large arrays of intersectingnanowires called crossbars provide the basi...
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1. Moving beyond today's silicon integrated chip technology will requireshrinking logic and memory circuits to the scale of a few nanometers. Large arrays of intersectingnanowires called crossbars provide the basis for one of the best candidate technologies fornanocomputing success. 2. The nanowires that comprise crossbars are so small that atomic defects andflaws in their manufacture are unavoidable and serious. Building redundancy into the circuitry andusingcodingtheory techniques compensate forthe many imperfections.
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