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Diffstat (limited to 'Alc/filters/biquad.cpp')
-rw-r--r-- | Alc/filters/biquad.cpp | 127 |
1 files changed, 0 insertions, 127 deletions
diff --git a/Alc/filters/biquad.cpp b/Alc/filters/biquad.cpp deleted file mode 100644 index 6a3cef64..00000000 --- a/Alc/filters/biquad.cpp +++ /dev/null @@ -1,127 +0,0 @@ - -#include "config.h" - -#include "biquad.h" - -#include <algorithm> -#include <cassert> -#include <cmath> - -#include "opthelpers.h" - - -template<typename Real> -void BiquadFilterR<Real>::setParams(BiquadType type, Real gain, Real f0norm, Real rcpQ) -{ - // Limit gain to -100dB - assert(gain > 0.00001f); - - const Real w0{al::MathDefs<Real>::Tau() * f0norm}; - const Real sin_w0{std::sin(w0)}; - const Real cos_w0{std::cos(w0)}; - const Real alpha{sin_w0/2.0f * rcpQ}; - - 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) - { - case BiquadType::HighShelf: - sqrtgain_alpha_2 = 2.0f * std::sqrt(gain) * alpha; - b[0] = gain*((gain+1.0f) + (gain-1.0f)*cos_w0 + sqrtgain_alpha_2); - b[1] = -2.0f*gain*((gain-1.0f) + (gain+1.0f)*cos_w0 ); - b[2] = gain*((gain+1.0f) + (gain-1.0f)*cos_w0 - sqrtgain_alpha_2); - a[0] = (gain+1.0f) - (gain-1.0f)*cos_w0 + sqrtgain_alpha_2; - a[1] = 2.0f* ((gain-1.0f) - (gain+1.0f)*cos_w0 ); - a[2] = (gain+1.0f) - (gain-1.0f)*cos_w0 - sqrtgain_alpha_2; - break; - case BiquadType::LowShelf: - sqrtgain_alpha_2 = 2.0f * std::sqrt(gain) * alpha; - b[0] = gain*((gain+1.0f) - (gain-1.0f)*cos_w0 + sqrtgain_alpha_2); - b[1] = 2.0f*gain*((gain-1.0f) - (gain+1.0f)*cos_w0 ); - b[2] = gain*((gain+1.0f) - (gain-1.0f)*cos_w0 - sqrtgain_alpha_2); - a[0] = (gain+1.0f) + (gain-1.0f)*cos_w0 + sqrtgain_alpha_2; - a[1] = -2.0f* ((gain-1.0f) + (gain+1.0f)*cos_w0 ); - a[2] = (gain+1.0f) + (gain-1.0f)*cos_w0 - sqrtgain_alpha_2; - break; - case BiquadType::Peaking: - gain = std::sqrt(gain); - b[0] = 1.0f + alpha * gain; - b[1] = -2.0f * cos_w0; - b[2] = 1.0f - alpha * gain; - a[0] = 1.0f + alpha / gain; - a[1] = -2.0f * cos_w0; - a[2] = 1.0f - alpha / gain; - break; - - case BiquadType::LowPass: - b[0] = (1.0f - cos_w0) / 2.0f; - b[1] = 1.0f - cos_w0; - b[2] = (1.0f - cos_w0) / 2.0f; - a[0] = 1.0f + alpha; - a[1] = -2.0f * cos_w0; - a[2] = 1.0f - alpha; - break; - case BiquadType::HighPass: - b[0] = (1.0f + cos_w0) / 2.0f; - b[1] = -(1.0f + cos_w0); - b[2] = (1.0f + cos_w0) / 2.0f; - a[0] = 1.0f + alpha; - a[1] = -2.0f * cos_w0; - a[2] = 1.0f - alpha; - break; - case BiquadType::BandPass: - b[0] = alpha; - b[1] = 0.0f; - b[2] = -alpha; - a[0] = 1.0f + alpha; - a[1] = -2.0f * cos_w0; - a[2] = 1.0f - alpha; - break; - } - - a1 = a[1] / a[0]; - a2 = a[2] / a[0]; - b0 = b[0] / a[0]; - b1 = b[1] / a[0]; - b2 = b[2] / a[0]; -} - -template<typename Real> -void BiquadFilterR<Real>::process(Real *dst, const Real *src, int numsamples) -{ - ASSUME(numsamples > 0); - - 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- - * sample history; the last two inputs and outputs), and works better for - * floating-point which favors summing similarly-sized values while being - * less bothered by overflow. - * - * See: http://www.earlevel.com/main/2003/02/28/biquads/ - */ - auto proc_sample = [b0,b1,b2,a1,a2,&z1,&z2](Real input) noexcept -> Real - { - Real output = input*b0 + z1; - z1 = input*b1 - output*a1 + z2; - z2 = input*b2 - output*a2; - return output; - }; - std::transform(src, src+numsamples, dst, proc_sample); - - this->z1 = z1; - this->z2 = z2; -} - -template class BiquadFilterR<float>; -template class BiquadFilterR<double>; |