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audio-algo-drain/audio/algo/drain/BiQuad.h

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/** @file
* @author Edouard DUPIN
* @copyright 2011, Edouard DUPIN, all right reserved
* @license APACHE v2.0 (see license file)
*/
#ifndef __AUDIO_ALGO_DRAIN_ALGO_BIQUAD_H__
#define __AUDIO_ALGO_DRAIN_ALGO_BIQUAD_H__
#include <etk/memory.h>
#include <audio/algo/drain/BiQuadType.h>
#include <cmath>
namespace audio {
namespace algo {
namespace drain {
template<typename TYPE> class BiQuad {
public:
BiQuad() {
reset();
// reset coefficients
m_a[0] = 1.0;
m_a[1] = 0.0;
m_a[2] = 0.0;
m_b[0] = 0.0;
m_b[1] = 0.0;
}
protected:
TYPE m_x[2]; //!< X history
TYPE m_y[2]; //!< Y histiry
TYPE m_a[3]; //!< A bi-Quad coef
TYPE m_b[2]; //!< B bi-Quad coef
public:
/**
* @brief Set the bi-quad value and type
* @param[in] _type Type of biquad.
* @param[in] _frequencyCut Cut Frequency. [0..sampleRate/2]
* @param[in] _qualityFactor Q factor of quality (good value of 0.707 ==> permit to not ower gain) limit [0.01 .. 10]
* @param[in] _gain Gain to apply (for notch, peak, lowShelf and highShelf) limit : -30, +30
* @param[in] _sampleRate Sample rate of the signal
*/
void setBiquad(enum audio::algo::drain::biQuadType _type, double _frequencyCut, double _qualityFactor, double _gain, float _sampleRate) {
reset();
if (_sampleRate < 1) {
m_a[0] = 1.0;
m_a[1] = 0.0;
m_a[2] = 0.0;
m_b[0] = 0.0;
m_b[1] = 0.0;
return;
}
if (_frequencyCut > _sampleRate/2) {
_frequencyCut = _sampleRate/2;
} else if (_frequencyCut < 0) {
_frequencyCut = 0;
}
if (_qualityFactor < 0.01) {
_qualityFactor = 0.01;
}
double norm;
double V = std::pow(10.0, std::abs(_gain) / 20.0);
double K = std::tan(M_PI * _frequencyCut / _sampleRate);
switch (_type) {
case biQuadType_none:
m_a[0] = 1.0;
m_a[1] = 0.0;
m_a[2] = 0.0;
m_b[0] = 0.0;
m_b[1] = 0.0;
break;
case biQuadType_lowPass:
norm = 1.0 / (1.0 + K / _qualityFactor + K * K);
m_a[0] = K * K * norm;
m_a[1] = m_a[0] * 2.0;
m_a[2] = m_a[0];
m_b[0] = 2.0 * (K * K - 1.0) * norm;
m_b[1] = (1.0 - K / _qualityFactor + K * K) * norm;
break;
case biQuadType_highPass:
norm = 1.0 / (1.0 + K / _qualityFactor + K * K);
m_a[0] = 1.0 * norm;
m_a[1] = m_a[0] * -2.0;
m_a[2] = m_a[0];
m_b[0] = 2.0 * (K * K - 1.0) * norm;
m_b[1] = (1.0 - K / _qualityFactor + K * K) * norm;
break;
case biQuadType_bandPass:
norm = 1.0 / (1.0 + K / _qualityFactor + K * K);
m_a[0] = K / _qualityFactor * norm;
m_a[1] = 0.0;
m_a[2] = m_a[0] * -1.0;
m_b[0] = 2.0 * (K * K - 1.0) * norm;
m_b[1] = (1.0 - K / _qualityFactor + K * K) * norm;
break;
case biQuadType_notch:
norm = 1.0 / (1.0 + K / _qualityFactor + K * K);
m_a[0] = (1.0 + K * K) * norm;
m_a[1] = 2.0 * (K * K - 1.0) * norm;
m_a[2] = m_a[0];
m_b[0] = m_a[1];
m_b[1] = (1.0 - K / _qualityFactor + K * K) * norm;
break;
case biQuadType_peak:
if (_gain >= 0.0) {
norm = 1.0 / (1.0 + 1.0/_qualityFactor * K + K * K);
m_a[0] = (1.0 + V/_qualityFactor * K + K * K) * norm;
m_a[1] = 2.0 * (K * K - 1.0) * norm;
m_a[2] = (1.0 - V/_qualityFactor * K + K * K) * norm;
m_b[0] = m_a[1];
m_b[1] = (1.0 - 1.0/_qualityFactor * K + K * K) * norm;
} else {
norm = 1.0 / (1.0 + V/_qualityFactor * K + K * K);
m_a[0] = (1.0 + 1.0/_qualityFactor * K + K * K) * norm;
m_a[1] = 2.0 * (K * K - 1.0) * norm;
m_a[2] = (1.0 - 1.0/_qualityFactor * K + K * K) * norm;
m_b[0] = m_a[1];
m_b[1] = (1.0 - V/_qualityFactor * K + K * K) * norm;
}
break;
case biQuadType_lowShelf:
if (_gain >= 0) {
norm = 1.0 / (1.0 + M_SQRT2 * K + K * K);
m_a[0] = (1.0 + std::sqrt(2.0*V) * K + V * K * K) * norm;
m_a[1] = 2.0 * (V * K * K - 1.0) * norm;
m_a[2] = (1.0 - std::sqrt(2.0*V) * K + V * K * K) * norm;
m_b[0] = 2.0 * (K * K - 1.0) * norm;
m_b[1] = (1.0 - M_SQRT2 * K + K * K) * norm;
} else {
norm = 1.0 / (1.0 + std::sqrt(2.0*V) * K + V * K * K);
m_a[0] = (1.0 + M_SQRT2 * K + K * K) * norm;
m_a[1] = 2.0 * (K * K - 1.0) * norm;
m_a[2] = (1.0 - M_SQRT2 * K + K * K) * norm;
m_b[0] = 2.0 * (V * K * K - 1.0) * norm;
m_b[1] = (1.0 - std::sqrt(2.0*V) * K + V * K * K) * norm;
}
break;
case biQuadType_highShelf:
if (_gain >= 0) {
norm = 1.0 / (1.0 + M_SQRT2 * K + K * K);
m_a[0] = (V + std::sqrt(2.0*V) * K + K * K) * norm;
m_a[1] = 2.0 * (K * K - V) * norm;
m_a[2] = (V - std::sqrt(2.0*V) * K + K * K) * norm;
m_b[0] = 2.0 * (K * K - 1.0) * norm;
m_b[1] = (1.0 - M_SQRT2 * K + K * K) * norm;
} else {
norm = 1.0 / (V + std::sqrt(2.0*V) * K + K * K);
m_a[0] = (1.0 + M_SQRT2 * K + K * K) * norm;
m_a[1] = 2.0 * (K * K - 1.0) * norm;
m_a[2] = (1.0 - M_SQRT2 * K + K * K) * norm;
m_b[0] = 2.0 * (K * K - V) * norm;
m_b[1] = (V - std::sqrt(2.0*V) * K + K * K) * norm;
}
break;
}
}
/**
* @brief Set direct Coefficients
*/
void setBiquadCoef(TYPE _a0, TYPE _a1, TYPE _a2, TYPE _b0, TYPE _b1) {
m_a[0] = _a0;
m_a[1] = _a1;
m_a[2] = _a2;
m_b[0] = _b0;
m_b[1] = _b1;
reset();
}
/**
* @brief Get direct Coefficients
*/
void getBiquadCoef(TYPE& _a0, TYPE& _a1, TYPE& _a2, TYPE& _b0, TYPE& _b1) {
_a0 = m_a[0];
_a1 = m_a[1];
_a2 = m_a[2];
_b0 = m_b[0];
_b1 = m_b[1];
}
/**
* @brief Get direct Coefficients
*/
std::vector<TYPE> getCoef() {
std::vector<TYPE> out;
out.push_back(m_a[0]);
out.push_back(m_a[1]);
out.push_back(m_a[2]);
out.push_back(m_b[0]);
out.push_back(m_b[1]);
return out;
}
/**
* @brief Reset bequad filter (only history not value).
*/
void reset() {
m_x[0] = 0;
m_y[1] = 0;
m_x[0] = 0;
m_y[1] = 0;
}
protected:
/**
* @brief process single sample in float.
* @param[in] _sample Sample to process
* @return updataed value
*/
TYPE process(TYPE _sample) {
TYPE result;
// compute
result = m_a[0] * _sample
+ m_a[1] * m_x[0]
+ m_a[2] * m_x[1]
- m_b[0] * m_y[0]
- m_b[1] * m_y[1];
//update history of X
m_x[1] = m_x[0];
m_x[0] = _sample;
//update history of Y
m_y[1] = m_y[0];
m_y[0] = result;
return result;
}
public:
/**
* @brief Porcess function.
* param[in] _input Pointer on the input data.
* param[in,out] _output Poirter on the output data (can be the same as input (inplace availlable).
* param[in] _nbChunk Number of qample to process.
* param[in] _inputOffset Offset to add when read input data.
* param[in] _outputOffset Offset to add when write output data.
*/
void process(const TYPE* _input,
TYPE* _output,
size_t _nbChunk,
int32_t _inputOffset,
int32_t _outputOffset) {
for (size_t iii=0; iii<_nbChunk; ++iii) {
// process in float the biquad.
*_output = process(*_input);
// move to the sample on the same channel.
_input += _inputOffset;
_output += _outputOffset;
}
}
/**
* @brief calculate respond of the filter:
* @param[in] _sampleRate input qample rate
* @retrun list of frequency/power in dB
*/
std::vector<std::pair<float,float> > calculateTheory(double _sampleRate){
std::vector<std::pair<float,float> > out;
double norm;
bool buildLinear = true;
size_t len = 512;
for (size_t iii=0; iii < len; iii++) {
double w;
if (buildLinear == true) {
// 0 to pi, linear scale
w = iii / (len - 1.0) * M_PI;
} else {
// 0.001 to 1, times pi, log scale
w = std::exp(std::log(1.0 / 0.001) * iii / (len - 1.0)) * 0.001 * M_PI;
}
double freq = iii / (len - 1.0) * _sampleRate / 2.0;
double phi = std::pow(std::sin(w/2.0), 2.0);
double y = std::log( std::pow((m_a[0]+m_a[1]+m_a[2]).getDouble(), 2.0)
- 4.0*((m_a[0]*m_a[1]).getDouble() + 4.0*(m_a[0]*m_a[2]).getDouble() + (m_a[1]*m_a[2]).getDouble())*phi
+ 16.0*(m_a[0]*m_a[2]).getDouble()*phi*phi)
- std::log( std::pow(1.0+(m_b[0]+m_b[1]).getDouble(), 2.0)
- 4.0*((m_b[0]).getDouble() + 4.0*(m_b[1]).getDouble() + (m_b[0]*m_b[1]).getDouble())*phi
+ 16.0*m_b[1].getDouble()*phi*phi);
y = y * 10.0 / M_LN10;
if (y <= -200) {
y = -200.0;
}
//APPL_DEBUG("theory = " << freq << " power=" << y);
out.push_back(std::make_pair<float,float>(freq, y));
}
return out;
}
};
}
}
}
#endif
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