Showing papers on "Quadrature mirror filter published in 2018"

Gait Recognition by Cross Wavelet Transform and Graph Model

Abstract: In this paper, a multi-view gait based human recognition system using the fusion of two kinds of features is proposed. We use cross wavelet transform to extract dynamic feature and bipartite graph model to extract static feature which are coefficients of quadrature mirror filter U+0028 QMF U+0029-graph wavelet filter bank. Feature fusion is done after normalization. For normalization of features, min-max rule is used and mean-variance method is used to find weights for normalized features. Euclidean distance between each feature vector and center of the cluster which is obtained by k-means clustering is used as similarity measure in Bayesian framework. Experiments performed on widely used CASIA B gait database show that, the fusion of these two feature sets preserve discriminant information. We report 99.90 U+0025 average recognition rate.

Filters for anisotropic wavelet decompositions

Abstract: Like the continous shearlet transform and their relatives, discrete transformations based on the interplay between several filterbanks with anisotropic dilations provide a high potential to recover directed features in two and more dimensions. Due to simplicity, most of the directional systems constructed so far were using prediction--correction methods based on interpolatory subdivision schemes. In this paper, we give a simple but effective construction for QMF (quadrature mirror filter) filterbanks which are the discrete object between orthogonal wavelet analysis. We also characterize when the filterbank gives rise to the existence of refinable functions and hence wavelets and give a generalized shearlet construction for arbitrary dimensions and arbitrary scalings for which the filterbank construction ensures the existence of an orthogonal wavelet analysis.

Design of Recursive Digital Filters for Subband Coding

Abstract: Direct synthesis of the recursive lowpass prototype filter of quadrature mirror filter bank with nearly perfect reconstruction is described in this paper. Passband attenuation characteristic of this prototype digital filter is placed in the area between Butterworth and Elliptic attenuation characteristics. By complementary filter decomposition technique this filter is decomposed into parallel connection of two allpass filters. Then lowpass/highpass filters are obtained by adding/subtracting of these allpass filters, respectively. The main advantages of this kind of filters are hardware reduction, cost savings and smaller sensitivity to digital word length changing.

Cosine/Sine-Modulated Analysis/Synthesis Filter Banks

Abstract: One of the topics in multi-rate digital signal processing is the theory and design of M-band (or M-channel) analysis and synthesis quadrature mirror filter (QMF) banks for sub-band signal decomposition and coding. They are also called M-band maximally decimated critically sampled QMF banks. The analysis QMF bank consists of M uniform and equally spaced channel filters to decompose the input signal into M sub-band signals. The synthesis QMF bank consists of channel filters to reconstruct the original signal exactly from sub-band signals, or to recover a signal which is nearly perfect approximation of the original signal. Historically, discovering the 2-band QMF banks in 1976 stimulated and started research activities leading to extending the theory of near-perfect and perfect reconstruction QMF banks for arbitrary number of sub-bands, to developing a family of near-perfect modulated filter banks (or pseudo-QMF banks) and perfect reconstruction modulated filter banks based on the concept of time domain aliasing cancellation.

Multirate Digital Signal Processing

Abstract: This chapter deals with Sampling rate conversion, polyphase realization of FIR filters It describes the methodology of decomposing the input signals using Quadrature Mirror Filter It also describes the method of converting Time division multiplexing data into Frequency division multiplexing data using transmultiplexer

Bandwidth Extension of Speech Signals Using Quadrature Mirror Filter (QMF)

Abstract: Telephone networks normally transmit narrowband (NB) speech with a bandwidth restricted to 300 Hz to 3.4 kHz. While human speech comprises frequencies even further than the NB, there is a degradation of speech quality and intelligibility in such networks. This can be enhanced by recovering the speech components existing beyond the telephone bandwidth using Quadrature Mirror Filter (QMF) to give a perceptually superior wideband (WB) speech signal. QMF banks utilized as the fundamental mathematical tools to analyze and synthesize speech signals to coding of speech signal in sub-bands. Utilization of QMF's allows evading the aliasing effects due to samples decimation when signal is divide into sub-bands. In this paper, the performance of bandwidth extension (BWE) of speech through QMF was assessed by objective parameters like Log Spectral Distortion (LSD) and Itakura-Saito distance (ISD) and subjective parameters like Mean opinion score (MOS), Absolute Category Rating (ACR), Comparison Category Rating (CCR) and Perceptual Evaluation of Speech Quality (PESQ) which demonstrates that the recovered WB speech signal provides speech quality compared by original WB speech signal.

An Iterative Reweighted Minimax Algorithm for the Design of FRM-based Two-channel QMF Banks

Abstract: The optimal design of two-channel FIR quadrature mirror filter (QMF) banks based on the Frequency-Response-Masking (FRM) technique is studied in this paper. An iterative algorithm is proposed to design a prototype filter. In each iteration of the algorithm, the prototype filter is optimized in the constrained weighted minimax sense with the weighting function being updated for reducing the reconstruction error of the filter banks. Further, we give an alternating variable approach to solving these constrained weighted minimax design problems of FRM filters. Specifically, it converts the nonlinear best approximation problem into a series of linear best approximation subproblems and solves each one using an efficient Goldfarb-Idnani based algorithm. The proposed filter banks have lower overall arithmetic complexity compared with the conventional ones. An example is presented and the simulation results show the proposed method performs better than an existing method.

Improved Design of Two-Channel Quadrature Mirror Filter Using Explicit Toeplitz Expressions

Abstract: Design of quadrature mirror filter banks based on all-pass filters in the least-squares sense can be reduced to solve a set of linear equations associated with desired phases. This paper proposes explicit formula for Toeplitz and Hankel matrices that required in solving the set of linear equations such that the filter coefficients can be derived by using efficient algorithm.

Spectral Band Replication Compression Technology: Efficient Implementations of Complex Exponential- and Cosine-Modulated QMF Banks

Abstract: Spectral Band Replication (SBR) is an enhancement compression technology. The SBR is a bandwidth extension method which significantly improves the compression efficiency of perceptual audio and speech coding schemes. There are two versions of the SBR technology: Standard SBR and Low Delay SBR (LD-BR). Central to the operation of standard SBR and LD-SBR are dedicated complex exponential-modulated and real-valued cosine-modulated quadrature mirror filter (QMF) banks as the basic mathematical tools to analyze and synthesize audio signals. This chapter presents the complete unified efficient implementations of complex exponential-modulated and real-valued cosine-modulated QMF banks used both in the standard SBR and LD-SBR encoder and decoder. In general, for each QMF bank is presented: Definition in its equivalent block transform with a common parameter M representing the number of sub-bands, its general symmetry property in the frequency or time domain, and the derivation of a fast algorithm for its efficient implementation. All the fast algorithms are analyzed in detail in terms of the arithmetic complexity, regularity, and structural simplicity for a potential real-time low-cost implementation in hardware or software.

Quadrature mirror filter based processing data time matching

Abstract: FIELD: acoustics.SUBSTANCE: invention relates to the processing data time matching means based on the quadrature mirror filter. Determining the audio signal reconstructed frame by the received data stream access block. Wherein the access block contains the signal waveform data and metadata. Wherein the signa waveform data and metadata are associated with the same audio signal reconstructed frame. By the waveform data generating plurality of sub-band signals forms. By the metadata generating the decoded metadata. Time matching the plurality of sub-band signals forms and decoded metadata. By the time matched plurality of sub-band signals forms and decoded metadata generating the audio signal recovered frame.EFFECT: reduction in the sound encoding and decoding delay.37 cl, 6 dwg, 1 tbl

Efficient Implementations of Cosine-Modulated Pseudo-QMF and MLT (MDCT) Filter Banks in MP3

Abstract: The MPEG-1 and MPEG-2 audio have been the first international audio coding standards specifying the digital format for high quality compression of audio signals. For the time-to-frequency transformation of an audio signal and vice versa, the MPEG-1/2 in layers I and II has adopted a near perfect reconstruction cosine-modulated polyphase quadrature mirror filter (QMF) banks, also referred to as the pseudo-QMF banks. In layer III (known as MP3) it has additionally adopted the perfect reconstruction modulated lapped transform (MLT) which is actually the modified discrete cosine transform (MDCT) associated with the sine windowing function. This chapter describes and compares various efficient implementations of the forward and backward MLT (MDCT) in the MP3 audio coding standard developed in the time period 1990–2012, including the efficient implementation of pseudo-QMF banks for completeness. The efficient MLT (MDCT) implementations are discussed in the context of complete (fast) analysis/synthesis MLT (MDCT) filter banks in the MP3 encoder and decoder. In general, for each efficient forward/backward MLT (MDCT) block transforms implementation are presented: complete formulae or (block) sparse matrix factorizations, the corresponding signal flow graph for short audio block, and the total arithmetic complexity as well as the useful comments related to improving the arithmetic complexity and a possible structural simplification of the algorithm. Finally, the fast analysis and synthesis MLT (MDCT) filter banks for MP3 encoder and decoder are discussed in detail. Appendices provide all the necessary supporting efficient optimized short-length computational modules and tools for completing efficient forward/backward MLT (MDCT) implementations.