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// Copyright (C) 2010-2016 Lukas Lalinsky
// Distributed under the MIT license, see the LICENSE file for details.
#include <limits>
#include <cmath>
#include "fft_frame.h"
#include "utils.h"
#include "chroma.h"
#include "debug.h"
namespace chromaprint {
static const int NUM_BANDS = 12;
inline double FreqToOctave(double freq, double base = 440.0 / 16.0)
{
return log(freq / base) / log(2.0);
}
Chroma::Chroma(int min_freq, int max_freq, int frame_size, int sample_rate, FeatureVectorConsumer *consumer)
: m_interpolate(false),
m_notes(frame_size),
m_notes_frac(frame_size),
m_features(NUM_BANDS),
m_consumer(consumer)
{
PrepareNotes(min_freq, max_freq, frame_size, sample_rate);
}
Chroma::~Chroma()
{
}
void Chroma::PrepareNotes(int min_freq, int max_freq, int frame_size, int sample_rate)
{
m_min_index = std::max(1, FreqToIndex(min_freq, frame_size, sample_rate));
m_max_index = std::min(frame_size / 2, FreqToIndex(max_freq, frame_size, sample_rate));
for (int i = m_min_index; i < m_max_index; i++) {
double freq = IndexToFreq(i, frame_size, sample_rate);
double octave = FreqToOctave(freq);
double note = NUM_BANDS * (octave - floor(octave));
m_notes[i] = (char)note;
m_notes_frac[i] = note - m_notes[i];
}
}
void Chroma::Reset()
{
}
void Chroma::Consume(const FFTFrame &frame)
{
fill(m_features.begin(), m_features.end(), 0.0);
for (int i = m_min_index; i < m_max_index; i++) {
int note = m_notes[i];
double energy = frame[i];
if (m_interpolate) {
int note2 = note;
double a = 1.0;
if (m_notes_frac[i] < 0.5) {
note2 = (note + NUM_BANDS - 1) % NUM_BANDS;
a = 0.5 + m_notes_frac[i];
}
if (m_notes_frac[i] > 0.5) {
note2 = (note + 1) % NUM_BANDS;
a = 1.5 - m_notes_frac[i];
}
m_features[note] += energy * a;
m_features[note2] += energy * (1.0 - a);
}
else {
m_features[note] += energy;
}
}
m_consumer->Consume(m_features);
}
}; // namespace chromaprint
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