53 research outputs found
A Proper version of Synthesis-based Sparse Audio Declipper
Methods based on sparse representation have found great use in the recovery
of audio signals degraded by clipping. The state of the art in declipping has
been achieved by the SPADE algorithm by Kiti\'c et. al. (LVA/ICA2015). Our
recent study (LVA/ICA2018) has shown that although the original S-SPADE can be
improved such that it converges significantly faster than the A-SPADE, the
restoration quality is significantly worse. In the present paper, we propose a
new version of S-SPADE. Experiments show that the novel version of S-SPADE
outperforms its old version in terms of restoration quality, and that it is
comparable with the A-SPADE while being even slightly faster than A-SPADE
Multiple Hankel matrix rank minimization for audio inpainting
Sasaki et al. (2018) presented an efficient audio declipping algorithm, based
on the properties of Hankel-structured matrices constructed from time-domain
signal blocks. We adapt their approach to solve the audio inpainting problem,
where samples are missing in the signal. We analyze the algorithm and provide
modifications, some of them leading to an improved performance. Overall, it
turns out that the new algorithms perform reasonably well for speech signals
but they are not competitive in the case of music signals
A method to study ageing of polydomain ferroelectrics using measurements of nonlinear permittivity
It is known that the permittivity of the ferroelectric films is affected by
several phenomena, which deteriorate the material quality (e.g. the
redistribution of the crystal lattice defects, appearance of the
electrode-adjacent non-ferroelectric layers or the spontaneous polarization
screening due to a free charge injection across the electrode-adjacent layer,
etc.). It is also known that the permittivity of ferroelectric polydomain films
is controlled by the sum of two contributions: the crystal lattice (intrinsic)
contribution and the domain wall movement (extrinsic) contribution. It is the
latter one, which is very sensitive to the aforementioned phenomena and which
plays a key role in the deterioration of the dielectric response of the
ferroelectric polydomain films. In this Article, there is presented a method
for the identification of the process, which is responsible for the
ferroelectric ageing. The method is based on the analysis of the evolution of
both the linear and nonlinear permittivity during ageing. Applicability of the
method is theoretically demonstrated on four ageing scenarios in two
qualitatively different systems where the evolution of the nonlinear
permittivity is controlled, first, by a redistribution of the pinning centers
on the domain wall and, second, by microstructural changes at the interface
between the ferroelectric layer and the electrode. It is shown that each ageing
scenario is characterized by unique trend in the evolution between the linear
and nonlinear part of the permittivity, which can be verified experimentally.Comment: Submitted to Ferroelectric
Audio declipping performance enhancement via crossfading
Some audio declipping methods produce waveforms that do not fully respect the actual process of clipping and allow a deviation on the reliable samples. This article reports what effect on perception it has if the output of such “inconsistent” methods is pushed towards “consistent” solutions by postprocessing. We first propose a simple sample replacement method, then we identify its main weaknesses and propose an improved variant. The experiments show that the vast majority of inconsistent declipping methods significantly benefit from the proposed approach in terms of objective perceptual metrics. In particular, we show that the SS PEW method based on social sparsity combined with the proposed method performs comparable to top methods from the consistent class, but at a computational cost of one order of magnitude lower
Audio Dequantization Using (Co)Sparse (Non)Convex Methods
The paper deals with the hitherto neglected topic of audio dequantization. It reviews the state-of-the-art sparsity-based approaches and proposes several new methods. Convex as well as non-convex approaches are included, and all the presented formulations come in both the synthesis and analysis variants. In the experiments the methods are evaluated using the signal-to-distortion ratio (SDR) and PEMO-Q, a perceptually motivated metric
A new generalized projection and its application to acceleration of audio declipping
In convex optimization, it is often inevitable to work with projectors onto convex sets composed with a linear operator. Such a need arises from both the theory and applications, with signal processing being a prominent and broad field where convex optimization has been used recently. In this article, a novel projector is presented, which generalizes previous results in that it admits to work with a broader family of linear transforms when compared with the state of the art but, on the other hand, it is limited to box-type convex sets in the transformed domain. The new projector is described by an explicit formula, which makes it simple to implement and requires a low computational cost. The projector is interpreted within the framework of the so-called proximal splitting theory. The convenience of the new projector is demonstrated on an example from signal processing, where it was possible to speed up the convergence of a signal declipping algorithm by a factor of more than two
Evidence for dielectric aging due to progressive 180 domain wall pinning in polydomain Pb(Zr0.45Ti0.55)O3 thin films
An evidence that the dielectric ageing in the polydomain Pb(Zr0.45Ti0.55)O3
thin films is controlled by progressive pinning of 180 domain walls is
presented. To provide such a conclusion, we use a general method, which is
based on the study of the time evolution of the nonlinear, but anhysteretic,
dielectric response of the ferroelectric to a weak electric field. A
thermodynamic model of the ferroelectric system where the dielectric response
is controlled by bending movements of pinned 180 domain walls is developed.
Within this model, the nonlinear permittivity of the ferroelectric is expressed
as a function of the microstructural parameters of the domain pattern. It is
shown that using the analysis of the time evolution of the nonlinear
permittivity, it is possible to estimate changes in the concentration of the
pinning centers that block the movements of the 180 domain walls during aging
in polydomain perovskite ferroelectrics.Comment: This version is modifed and corrected according to recently published
Erratum: Phys. Rev. B 79, 219903(E) (2009). 21 pages, 3 figure
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