92 lines
2.7 KiB
C++
92 lines
2.7 KiB
C++
/*
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* SpectralCentroidprint -- Audio fingerprinting toolkit
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* Copyright (C) 2010 Lukas Lalinsky <lalinsky@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
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* USA
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*/
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#include <limits>
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#include <math.h>
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#include "fft_frame.h"
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#include "utils.h"
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#include "spectral_centroid.h"
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using namespace std;
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using namespace Chromaprint;
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SpectralCentroid::SpectralCentroid(int num_bands, int min_freq, int max_freq, int frame_size, int sample_rate, FeatureVectorConsumer *consumer)
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: m_bands(num_bands + 1),
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m_features(num_bands),
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m_consumer(consumer)
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{
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PrepareBands(num_bands, min_freq, max_freq, frame_size, sample_rate);
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}
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SpectralCentroid::~SpectralCentroid()
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{
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}
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void SpectralCentroid::PrepareBands(int num_bands, int min_freq, int max_freq, int frame_size, int sample_rate)
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{
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double min_bark = FreqToBark(min_freq);
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double max_bark = FreqToBark(max_freq);
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double band_size = (max_bark - min_bark) / num_bands;
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int min_index = FreqToIndex(min_freq, frame_size, sample_rate);
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//int max_index = FreqToIndex(max_freq, frame_size, sample_rate);
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m_bands[0] = min_index;
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double prev_bark = min_bark;
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for (int i = min_index, b = 0; i < frame_size / 2; i++) {
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double freq = IndexToFreq(i, frame_size, sample_rate);
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double bark = FreqToBark(freq);
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if (bark - prev_bark > band_size) {
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b += 1;
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prev_bark = bark;
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m_bands[b] = i;
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if (b >= num_bands) {
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break;
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}
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}
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}
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}
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void SpectralCentroid::Reset()
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{
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}
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void SpectralCentroid::Consume(const FFTFrame &frame)
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{
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for (int i = 0; i < NumBands(); i++) {
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int first = FirstIndex(i);
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int last = LastIndex(i);
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double numerator = 0.0;
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double denominator = 0.0;
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for (int j = first; j < last; j++) {
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double s = frame.Energy(j);
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numerator += j * s;
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denominator += s;
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}
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double centroid = numerator / denominator;
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if (centroid != centroid)
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centroid = (first + last) / 2.0; // handle NaN
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m_features[i] = (centroid - first) / (last - first);
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}
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m_consumer->Consume(m_features);
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}
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