Dima353/openal-soft
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Make BiquadFilter a templated class

Browse Source 
With explicit instantiations for float and double
This commit is contained in:
Chris Robinson
2019-01-06 00:53:02 -08:00
parent 03aeb7edf6
commit 607e778344
2 changed files with 51 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Alc/filters/biquad.cpp
+24 -20
View File
@@ -10,19 +10,20 @@
#include "biquad.h"
void BiquadFilter::setParams(BiquadType type, float gain, float f0norm, float rcpQ)
template<typename Real>
void BiquadFilterR<Real>::setParams(BiquadType type, Real gain, Real f0norm, Real rcpQ)
{
// Limit gain to -100dB
assert(gain > 0.00001f);
const float w0{F_TAU * f0norm};
const float sin_w0{std::sin(w0)};
const float cos_w0{std::cos(w0)};
const float alpha{sin_w0/2.0f * rcpQ};
const Real w0{F_TAU * f0norm};
const Real sin_w0{std::sin(w0)};
const Real cos_w0{std::cos(w0)};
const Real alpha{sin_w0/2.0f * rcpQ};
float sqrtgain_alpha_2;
float a[3]{ 1.0f, 0.0f, 0.0f };
float b[3]{ 1.0f, 0.0f, 0.0f };
Real sqrtgain_alpha_2;
Real a[3]{ 1.0f, 0.0f, 0.0f };
Real b[3]{ 1.0f, 0.0f, 0.0f };
/* Calculate filter coefficients depending on filter type */
switch(type)
@@ -73,7 +74,7 @@ void BiquadFilter::setParams(BiquadType type, float gain, float f0norm, float rc
break;
case BiquadType::BandPass:
b[0] = alpha;
b[1] = 0;
b[1] = 0.0f;
b[2] = -alpha;
a[0] = 1.0f + alpha;
a[1] = -2.0f * cos_w0;
@@ -88,18 +89,18 @@ void BiquadFilter::setParams(BiquadType type, float gain, float f0norm, float rc
b2 = b[2] / a[0];
}
void BiquadFilter::process(float *dst, const float *src, int numsamples)
template<typename Real>
void BiquadFilterR<Real>::process(Real *dst, const Real *src, int numsamples)
{
ASSUME(numsamples > 0);
const float b0{this->b0};
const float b1{this->b1};
const float b2{this->b2};
const float a1{this->a1};
const float a2{this->a2};
float z1{this->z1};
float z2{this->z2};
const Real b0{this->b0};
const Real b1{this->b1};
const Real b2{this->b2};
const Real a1{this->a1};
const Real a2{this->a2};
Real z1{this->z1};
Real z2{this->z2};
/* Processing loop is Transposed Direct Form II. This requires less storage
* compared to Direct Form I (only two delay components, instead of a four-
@@ -109,9 +110,9 @@ void BiquadFilter::process(float *dst, const float *src, int numsamples)
*
* See: http://www.earlevel.com/main/2003/02/28/biquads/
*/
auto proc_sample = [b0,b1,b2,a1,a2,&z1,&z2](float input) noexcept -> float
auto proc_sample = [b0,b1,b2,a1,a2,&z1,&z2](Real input) noexcept -> Real
{
float output = input*b0 + z1;
Real output = input*b0 + z1;
z1 = input*b1 - output*a1 + z2;
z2 = input*b2 - output*a2;
return output;
@@ -121,3 +122,6 @@ void BiquadFilter::process(float *dst, const float *src, int numsamples)
this->z1 = z1;
this->z2 = z2;
}
template class BiquadFilterR<float>;
template class BiquadFilterR<double>;
Alc/filters/biquad.h
+27 -16
View File
@@ -34,13 +34,14 @@ enum class BiquadType {
BandPass,
};
class BiquadFilter {
template<typename Real>
class BiquadFilterR {
/* Last two delayed components for direct form II. */
float z1{0.0f}, z2{0.0f};
Real z1{0.0f}, z2{0.0f};
/* Transfer function coefficients "b" (numerator) */
float b0{1.0f}, b1{0.0f}, b2{0.0f};
Real b0{1.0f}, b1{0.0f}, b2{0.0f};
/* Transfer function coefficients "a" (denominator; a0 is pre-applied). */
float a1{0.0f}, a2{0.0f};
Real a1{0.0f}, a2{0.0f};
public:
void clear() noexcept { z1 = z2 = 0.0f; }
@@ -59,9 +60,9 @@ public:
* transition band. Can be generated from calc_rcpQ_from_slope
* or calc_rcpQ_from_bandwidth as needed.
*/
void setParams(BiquadType type, float gain, float f0norm, float rcpQ);
void setParams(BiquadType type, Real gain, Real f0norm, Real rcpQ);
void copyParamsFrom(const BiquadFilter &other)
void copyParamsFrom(const BiquadFilterR &other)
{
b0 = other.b0;
b1 = other.b1;
@@ -71,7 +72,7 @@ public:
}
void process(float *dst, const float *src, int numsamples);
void process(Real *dst, const Real *src, int numsamples);
void passthru(int numsamples) noexcept
{
@@ -88,19 +89,21 @@ public:
}
/* Rather hacky. It's just here to support "manual" processing. */
std::pair<float,float> getComponents() const noexcept
std::pair<Real,Real> getComponents() const noexcept
{ return {z1, z2}; }
void setComponents(float z1_, float z2_) noexcept
void setComponents(Real z1_, Real z2_) noexcept
{ z1 = z1_; z2 = z2_; }
float processOne(const float in, float &z1_, float &z2_) const noexcept
Real processOne(const Real in, Real &z1_, Real &z2_) const noexcept
{
float out{in*b0 + z1_};
Real out{in*b0 + z1_};
z1_ = in*b1 - out*a1 + z2_;
z2_ = in*b2 - out*a2;
return out;
}
};
using BiquadFilter = BiquadFilterR<float>;
/**
* Calculates the rcpQ (i.e. 1/Q) coefficient for shelving filters, using the
* reference gain and shelf slope parameter.
@@ -108,19 +111,27 @@ public:
* \param slope 0 < slope <= 1
*/
inline float calc_rcpQ_from_slope(float gain, float slope)
{
return std::sqrt((gain + 1.0f/gain)*(1.0f/slope - 1.0f) + 2.0f);
}
{ return std::sqrt((gain + 1.0f/gain)*(1.0f/slope - 1.0f) + 2.0f); }
inline double calc_rcpQ_from_slope(double gain, double slope)
{ return std::sqrt((gain + 1.0/gain)*(1.0/slope - 1.0) + 2.0); }
/**
* Calculates the rcpQ (i.e. 1/Q) coefficient for filters, using the normalized
* reference frequency and bandwidth.
* \param f0norm 0 < f0norm < 0.5.
* \param bandwidth 0 < bandwidth
*/
inline ALfloat calc_rcpQ_from_bandwidth(float f0norm, float bandwidth)
inline float calc_rcpQ_from_bandwidth(float f0norm, float bandwidth)
{
float w0 = F_TAU * f0norm;
const float w0{F_TAU * f0norm};
return 2.0f*std::sinh(std::log(2.0f)/2.0f*bandwidth*w0/std::sin(w0));
}
inline double calc_rcpQ_from_bandwidth(double f0norm, double bandwidth)
{
const double w0{F_TAU * f0norm};
return 2.0*std::sinh(std::log(2.0)/2.0*bandwidth*w0/std::sin(w0));
}
#endif /* FILTERS_BIQUAD_H */