4,956 research outputs found
Modern Methods of Time-Frequency Warping of Sound Signals
Tato práce se zabĂ˝vá reprezentacĂ nestacionárnĂch harmonickĂ˝ch signálĹŻ s ÄŤasovÄ› promÄ›nnĂ˝mi komponentami. PrimárnÄ› je zaměřena na Harmonickou transformaci a jeji variantu se subkvadratickou vĂ˝poÄŤetnĂ sloĹľitostĂ, Rychlou harmonickou transformaci. V tĂ©to práci jsou prezentovány dva algoritmy vyuĹľĂvajĂcĂ Rychlou harmonickou transformaci. Prvni pouĹľĂvá jako metodu odhadu zmÄ›ny základnĂho kmitoÄŤtu sbĂranĂ© logaritmickĂ© spektrum a druhá pouĹľĂvá metodu analĂ˝zy syntĂ©zou. Oba algoritmy jsou pouĹľity k analĂ˝ze Ĺ™eÄŤovĂ©ho segmentu pro porovnánĂ vystupĹŻ. Nakonec je algoritmus vyuĹľĂvajĂcĂ metody analĂ˝zy syntĂ©zou pouĹľit na reálnĂ© zvukovĂ© signály, aby bylo moĹľnĂ© změřit zlepšenĂ reprezentace kmitoÄŤtovÄ› modulovanĂ˝ch signálĹŻ za pouĹľitĂ HarmonickĂ© transformace.This thesis deals with representation of non-stationary harmonic signals with time-varying components. Its main focus is aimed at Harmonic Transform and its variant with subquadratic computational complexity, the Fast Harmonic Transform. Two algorithms using the Fast Harmonic Transform are presented. The first uses the gathered log-spectrum as fundamental frequency change estimation method, the second uses analysis-by-synthesis approach. Both algorithms are used on a speech segment to compare its output. Further the analysis-by-synthesis algorithm is applied on several real sound signals to measure the increase in the ability to represent real frequency-modulated signals using the Harmonic Transform.
Spectral analysis for nonstationary audio
A new approach for the analysis of nonstationary signals is proposed, with a
focus on audio applications. Following earlier contributions, nonstationarity
is modeled via stationarity-breaking operators acting on Gaussian stationary
random signals. The focus is on time warping and amplitude modulation, and an
approximate maximum-likelihood approach based on suitable approximations in the
wavelet transform domain is developed. This paper provides theoretical analysis
of the approximations, and introduces JEFAS, a corresponding estimation
algorithm. The latter is tested and validated on synthetic as well as real
audio signal.Comment: IEEE/ACM Transactions on Audio, Speech and Language Processing,
Institute of Electrical and Electronics Engineers, In pres
Analysis and application of digital spectral warping in analog and mixed-signal testing
Spectral warping is a digital signal processing transform which shifts the frequencies contained within a signal along the frequency axis. The Fourier transform coefficients of a warped signal correspond to frequency-domain 'samples' of the original signal which are unevenly spaced along the frequency axis. This property allows the technique to be efficiently used for DSP-based analog and mixed-signal testing. The analysis and application of spectral warping for test signal generation, response analysis, filter design, frequency response evaluation, etc. are discussed in this paper along with examples of the software and hardware implementation
An Improved Observation Model for Super-Resolution under Affine Motion
Super-resolution (SR) techniques make use of subpixel shifts between frames
in an image sequence to yield higher-resolution images. We propose an original
observation model devoted to the case of non isometric inter-frame motion as
required, for instance, in the context of airborne imaging sensors. First, we
describe how the main observation models used in the SR literature deal with
motion, and we explain why they are not suited for non isometric motion. Then,
we propose an extension of the observation model by Elad and Feuer adapted to
affine motion. This model is based on a decomposition of affine transforms into
successive shear transforms, each one efficiently implemented by row-by-row or
column-by-column 1-D affine transforms.
We demonstrate on synthetic and real sequences that our observation model
incorporated in a SR reconstruction technique leads to better results in the
case of variable scale motions and it provides equivalent results in the case
of isometric motions
Implementing 3D Warping Method In Wavelet Domain
A wide class of operations on images can be performed directly in the wavelet domain by operating on coefficients of the wavelet transforms of the images and other matrices defined by these operations. Operating in the wavelet domain enables one to perform these operations progressively in a coarse-to-fine fashion, operate on different resolutions, manipulate features at different scales, and localize the operation in both the spatial and the frequency domains. Performing such operations in the wavelet domain and then reconstructing the result is also often more efficient than performing the same operation in the standard direct fashion. Performing 3D warping in the wavelet domain is in many cases faster than their direct computation. In this paper we demonstrate our approach both on still and sequences of images
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