64 lines
1.7 KiB
C++
64 lines
1.7 KiB
C++
/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
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/*
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pYIN - A fundamental frequency estimator for monophonic audio
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Centre for Digital Music, Queen Mary, University of London.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version. See the file
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COPYING included with this distribution for more information.
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*/
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#ifndef _MEAN_FILTER_H_
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#define _MEAN_FILTER_H_
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class MeanFilter
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{
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public:
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/**
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* Construct a non-causal mean filter with filter length flen,
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* that replaces each sample N with the mean of samples
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* [N-floor(F/2) .. N+floor(F/2)] where F is the filter length.
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* Only odd F are supported.
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*/
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MeanFilter(int flen) : m_flen(flen) { }
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~MeanFilter() { }
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/**
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* Filter the n samples in "in" and place the results in "out"
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*/
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void filter(const double *in, double *out, const int n) {
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filterSubsequence(in, out, n, n, 0);
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}
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/**
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* Filter the n samples starting at the given offset in the
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* m-element array "in" and place the results in the n-element
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* array "out"
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*/
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void filterSubsequence(const double *in, double *out,
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const int m, const int n,
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const int offset) {
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int half = m_flen/2;
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for (int i = 0; i < n; ++i) {
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double v = 0;
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int n = 0;
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for (int j = -half; j <= half; ++j) {
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int ix = i + j + offset;
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if (ix >= 0 && ix < m) {
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v += in[ix];
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++n;
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}
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}
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out[i] = v / n;
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}
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}
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private:
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int m_flen;
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};
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#endif
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