28 lines
635 B
C++
28 lines
635 B
C++
#include "AUD_LowpassCalculator.h"
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#include <cmath>
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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AUD_LowpassCalculator::AUD_LowpassCalculator(float frequency, float Q) :
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m_frequency(frequency),
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m_Q(Q)
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{
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}
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void AUD_LowpassCalculator::recalculateCoefficients(AUD_SampleRate rate, std::vector<float> &b, std::vector<float> &a)
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{
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float w0 = 2 * M_PI * m_frequency / rate;
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float alpha = sin(w0) / (2 * m_Q);
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float norm = 1 + alpha;
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float c = cos(w0);
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a.push_back(1);
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a.push_back(-2 * c / norm);
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a.push_back((1 - alpha) / norm);
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b.push_back((1 - c) / (2 * norm));
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b.push_back((1 - c) / norm);
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b.push_back(b[0]);
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}
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