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/*************************************************************************** |
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* * |
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* LinuxSampler - modular, streaming capable sampler * |
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* * |
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* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck * |
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* Copyright (C) 2005 Christian Schoenebeck * |
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* Copyright (C) 2006 Christian Schoenebeck and Andreas Persson * |
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* * |
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* This program is free software; you can redistribute it and/or modify * |
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* it under the terms of the GNU General Public License as published by * |
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* the Free Software Foundation; either version 2 of the License, or * |
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* (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., 59 Temple Place, Suite 330, Boston, * |
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* MA 02111-1307 USA * |
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***************************************************************************/ |
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|
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#ifndef __LS_GIG_FILTER_H__ |
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#define __LS_GIG_FILTER_H__ |
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|
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#include "../../common/global.h" |
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|
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#include <gig.h> |
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|
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namespace LinuxSampler { namespace gig { |
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|
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class FilterBase { |
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public: |
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virtual float Apply(float x) = 0; |
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virtual void SetParameters(float f1, float f2, float scale) = 0; |
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virtual ~FilterBase() {} |
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|
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virtual void Reset() { |
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y1 = y2 = y3 = x1 = x2 = x3 = 0; |
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} |
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|
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private: |
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float y1, y2, y3; |
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|
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protected: |
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float a1, a2, a3, x1, x2, x3; |
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|
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void KillDenormal(float& f) { |
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f += 1e-18f; |
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f -= 1e-18f; |
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} |
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|
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float ApplyA(float x) { |
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float y = x - a1 * y1 - a2 * y2 - a3 * y3; |
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KillDenormal(y); |
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y3 = y2; |
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y2 = y1; |
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y1 = y; |
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return y; |
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} |
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}; |
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|
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class LowpassFilter : public FilterBase { |
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protected: |
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float b0; |
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public: |
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float Apply(float x) { |
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return ApplyA(b0 * x); |
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} |
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|
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void SetParameters(float f1, float f2, float scale) { |
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float f1_2 = f1 * f1; |
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b0 = f1_2 * scale; |
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a1 = f2; |
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a2 = f1_2 - 1; |
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a3 = -f2; |
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} |
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}; |
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|
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class BandpassFilter : public FilterBase { |
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float b0, b2; |
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public: |
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float Apply(float x) { |
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float y = ApplyA(b0 * x + b2 * x2); |
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x2 = x1; |
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x1 = x; |
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return y; |
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} |
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|
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void SetParameters(float f1, float f2, float scale) { |
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b0 = f1 * scale; |
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b2 = -b0; |
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a1 = f2; |
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a2 = f1 * f1 - 1; |
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a3 = -f2; |
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} |
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}; |
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|
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class HighpassFilter : public FilterBase { |
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float scale; |
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public: |
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float Apply(float x) { |
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float y = ApplyA(-x + x1 + x2 - x3); |
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x3 = x2; |
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x2 = x1; |
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x1 = x; |
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return y * scale; |
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} |
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|
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void SetParameters(float f1, float f2, float scale) { |
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a1 = f2; |
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a2 = f1 * f1 - 1; |
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a3 = -f2; |
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this->scale = scale; |
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} |
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}; |
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|
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class BandrejectFilter : public FilterBase { |
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float scale, b2; |
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public: |
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float Apply(float x) { |
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float y = ApplyA(x - x1 + b2 * x2 + x3); |
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x3 = x2; |
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x2 = x1; |
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x1 = x; |
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return y * scale; |
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} |
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|
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void SetParameters(float f1, float f2, float scale) { |
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b2 = f1 * f1 - 1; |
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a1 = f2; |
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a2 = b2; |
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a3 = -f2; |
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this->scale = scale; |
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} |
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}; |
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|
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class LowpassTurboFilter : public LowpassFilter { |
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float b20, y21, y22, y23; |
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public: |
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float Apply(float x) { |
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float y = b20 * LowpassFilter::Apply(x) |
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- a1 * y21 - a2 * y22 - a3 * y23; |
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KillDenormal(y); |
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y23 = y22; |
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y22 = y21; |
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y21 = y; |
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|
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return y; |
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} |
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|
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void SetParameters(float f1, float f2, float scale) { |
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LowpassFilter::SetParameters(f1, f2, scale); |
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b20 = b0 * 0.5; |
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} |
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|
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void Reset() { |
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LowpassFilter::Reset(); |
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y21 = y22 = y23 = 0; |
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} |
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}; |
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|
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/** |
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* These are filters similar to the ones from Gigasampler. |
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*/ |
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class Filter { |
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protected: |
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HighpassFilter HPFilter; |
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BandpassFilter BPFilter; |
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LowpassFilter LPFilter; |
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BandrejectFilter BRFilter; |
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LowpassTurboFilter LPTFilter; |
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FilterBase* pFilter; |
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|
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public: |
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Filter() { |
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// set filter type to 'lowpass' by default |
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pFilter = &LPFilter; |
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} |
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|
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void SetType(::gig::vcf_type_t FilterType) { |
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switch (FilterType) { |
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case ::gig::vcf_type_highpass: |
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pFilter = &HPFilter; |
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break; |
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case ::gig::vcf_type_bandreject: |
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pFilter = &BRFilter; |
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break; |
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case ::gig::vcf_type_bandpass: |
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pFilter = &BPFilter; |
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break; |
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case ::gig::vcf_type_lowpassturbo: |
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pFilter = &LPTFilter; |
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break; |
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default: |
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pFilter = &LPFilter; |
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} |
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} |
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|
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void SetParameters(float cutoff, float resonance, float fs) { |
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float f1 = cutoff * 0.0075279; |
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float f2 = f1 - 1 + resonance * cutoff * (-5.5389e-5 + 1.1982e-7 * cutoff); |
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float scale = resonance < 51 ? 1.0f : 1.3762f - 0.0075073f * resonance; |
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pFilter->SetParameters(f1, f2, scale); |
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} |
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|
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void Reset() { |
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HPFilter.Reset(); |
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BPFilter.Reset(); |
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LPFilter.Reset(); |
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BRFilter.Reset(); |
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LPTFilter.Reset(); |
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} |
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|
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float Apply(float in) { |
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return pFilter->Apply(in); |
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} |
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}; |
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|
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}} //namespace LinuxSampler::gig |
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|
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#endif // __LS_GIG_FILTER_H__ |