basic DSP lib (for lua bindings)
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/*
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* Copyright (C) 2016 Robin Gareus <robin@gareus.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#ifndef _dsp_filter_h_
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#define _dsp_filter_h_
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#include <stdint.h>
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#include "ardour/libardour_visibility.h"
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namespace ARDOUR { namespace DSP {
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void memset (float *data, const float val, const uint32_t n_samples);
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void mmult (float *data, float *mult, const uint32_t n_samples);
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class LIBARDOUR_API LowPass {
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public:
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LowPass (double samplerate, float freq);
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void proc (float *data, const uint32_t n_samples);
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void ctrl (float *data, const float val, const uint32_t n_samples);
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void set_cutoff (float freq);
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void reset () { _z = 0.f; }
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private:
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float _rate;
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float _z;
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float _a;
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};
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class LIBARDOUR_API BiQuad {
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public:
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enum Type {
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LowPass,
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HighPass,
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BandPassSkirt,
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BandPass0dB,
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Notch,
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AllPass,
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Peaking,
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LowShelf,
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HighShelf
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};
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BiQuad (double samplerate);
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BiQuad (const BiQuad &other);
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void run (float *data, const uint32_t n_samples);
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void compute (Type, double freq, double Q, double gain);
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void reset () { _z1 = _z2 = 0.0; }
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private:
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double _rate;
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float _z1, _z2;
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double _a1, _a2;
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double _b0, _b1, _b2;
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};
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} } /* namespace */
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#endif
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@ -0,0 +1,229 @@
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/*
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* Copyright (C) 2016 Robin Gareus <robin@gareus.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include <stdlib.h>
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#include <math.h>
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#include "ardour/dsp_filter.h"
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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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using namespace ARDOUR::DSP;
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void
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ARDOUR::DSP::memset (float *data, const float val, const uint32_t n_samples) {
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for (uint32_t i = 0; i < n_samples; ++i) {
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data[i] = val;
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}
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}
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void
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ARDOUR::DSP::mmult (float *data, float *mult, const uint32_t n_samples) {
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for (uint32_t i = 0; i < n_samples; ++i) {
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data[i] *= mult[i];
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}
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}
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LowPass::LowPass (double samplerate, float freq)
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: _rate (samplerate)
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, _z (0)
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{
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set_cutoff (freq);
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}
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void
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LowPass::set_cutoff (float freq)
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{
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_a = 1.f - expf (-2.f * M_PI * freq / _rate);
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}
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void
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LowPass::proc (float *data, const uint32_t n_samples)
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{
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// localize variables
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const float a = _a;
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float z = _z;
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for (uint32_t i = 0; i < n_samples; ++i) {
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data[i] += a * (data[i] - z);
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z = data[i];
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}
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_z = z;
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}
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void
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LowPass::ctrl (float *data, const float val, const uint32_t n_samples)
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{
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// localize variables
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const float a = _a;
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float z = _z;
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for (uint32_t i = 0; i < n_samples; ++i) {
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data[i] += a * (val - z);
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z = data[i];
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}
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_z = z;
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}
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///////////////////////////////////////////////////////////////////////////////
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BiQuad::BiQuad (double samplerate)
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: _rate (samplerate)
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, _z1 (0.0)
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, _z2 (0.0)
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, _a1 (0.0)
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, _a2 (0.0)
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, _b0 (1.0)
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, _b1 (0.0)
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, _b2 (0.0)
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{
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}
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BiQuad::BiQuad (const BiQuad &other)
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: _rate (other._rate)
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, _z1 (0.0)
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, _z2 (0.0)
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, _a1 (other._a1)
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, _a2 (other._a2)
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, _b0 (other._b0)
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, _b1 (other._b1)
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, _b2 (other._b2)
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{
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}
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void
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BiQuad::run (float *data, const uint32_t n_samples)
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{
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for (uint32_t i = 0; i < n_samples; ++i) {
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const float xn = data[i];
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const float z = _b0 * xn + _z1;
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_z1 = _b1 * xn - _a1 * z + _z2;
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_z2 = _b2 * xn - _a2 * z;
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data[i] = z;
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}
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}
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void
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BiQuad::compute (Type type, double freq, double Q, double gain)
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{
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/* Compute biquad filter settings.
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* Based on 'Cookbook formulae for audio EQ biquad filter coefficents'
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* by Robert Bristow-Johnson
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*/
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const double A = pow (10.0, (gain / 40.0));
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const double W0 = (2.0 * M_PI * freq) / _rate;
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const double sinW0 = sin (W0);
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const double cosW0 = cos (W0);
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const double alpha = sinW0 / (2.0 * Q);
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const double beta = sqrt (A) / Q;
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double _a0;
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switch (type) {
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case LowPass:
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_b0 = (1.0 - cosW0) / 2.0;
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_b1 = 1.0 - cosW0;
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_b2 = (1.0 - cosW0) / 2.0;
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_a0 = 1.0 + alpha;
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - alpha;
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break;
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case HighPass:
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_b0 = (1.0 + cosW0) / 2.0;
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_b1 = -(1.0 + cosW0);
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_b2 = (1.0 + cosW0) / 2.0;
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_a0 = 1.0 + alpha;
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - alpha;
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break;
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case BandPassSkirt: /* Constant skirt gain, peak gain = Q */
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_b0 = sinW0 / 2.0;
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_b1 = 0.0;
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_b2 = -sinW0 / 2.0;
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_a0 = 1.0 + alpha;
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - alpha;
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break;
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case BandPass0dB: /* Constant 0 dB peak gain */
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_b0 = alpha;
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_b1 = 0.0;
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_b2 = -alpha;
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_a0 = 1.0 + alpha;
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - alpha;
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break;
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case Notch:
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_b0 = 1.0;
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_b1 = -2.0 * cosW0;
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_b2 = 1.0;
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_a0 = 1.0 + alpha;
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - alpha;
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break;
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case AllPass:
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_b0 = 1.0 - alpha;
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_b1 = -2.0 * cosW0;
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_b2 = 1.0 + alpha;
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_a0 = 1.0 + alpha;
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - alpha;
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break;
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case Peaking:
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_b0 = 1.0 + (alpha * A);
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_b1 = -2.0 * cosW0;
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_b2 = 1.0 - (alpha * A);
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_a0 = 1.0 + (alpha / A);
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_a1 = -2.0 * cosW0;
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_a2 = 1.0 - (alpha / A);
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break;
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case LowShelf:
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_b0 = A * ((A + 1) - ((A - 1) * cosW0) + (beta * sinW0));
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_b1 = (2.0 * A) * ((A - 1) - ((A + 1) * cosW0));
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_b2 = A * ((A + 1) - ((A - 1) * cosW0) - (beta * sinW0));
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_a0 = (A + 1) + ((A - 1) * cosW0) + (beta * sinW0);
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_a1 = -2.0 * ((A - 1) + ((A + 1) * cosW0));
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_a2 = (A + 1) + ((A - 1) * cosW0) - (beta * sinW0);
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break;
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case HighShelf:
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_b0 = A * ((A + 1) + ((A - 1) * cosW0) + (beta * sinW0));
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_b1 = -(2.0 * A) * ((A - 1) + ((A + 1) * cosW0));
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_b2 = A * ((A + 1) + ((A - 1) * cosW0) - (beta * sinW0));
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_a0 = (A + 1) - ((A - 1) * cosW0) + (beta * sinW0);
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_a1 = 2.0 * ((A - 1) - ((A + 1) * cosW0));
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_a2 = (A + 1) - ((A - 1) * cosW0) - (beta * sinW0);
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break;
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default:
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abort(); /*NOTREACHED*/
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break;
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}
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_b0 /= _a0;
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_b1 /= _a0;
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_b2 /= _a0;
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_a1 /= _a0;
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_a2 /= _a0;
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}
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@ -65,6 +65,7 @@ libardour_sources = [
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'delivery.cc',
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'directory_names.cc',
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'diskstream.cc',
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'dsp_filter.cc',
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'ebur128_analysis.cc',
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'element_import_handler.cc',
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'element_importer.cc',
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