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92 lines
2.4 KiB
92 lines
2.4 KiB
/*
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Copyright (C) 2000 Jeff Tranter
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tranter@pobox.com
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(C) 1999 Stefan Westerfeld
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stefan@space.twc.de
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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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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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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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#include "artsmodulessynth.h"
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#include "stdsynthmodule.h"
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using namespace Arts;
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/*
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Try this. It's a really nice 4pole. Very Moog like.
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in[x] and out[x] are member variables, init to 0.0
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the controls:
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fc = cutoff, nearly linear [0,1] -> [0, fs/2]
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res = resonance [0, 4] -> [no resonance, self-oscillation]
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*/
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class Synth_MOOG_VCF_impl : virtual public Synth_MOOG_VCF_skel,
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virtual public StdSynthModule
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{
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protected:
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float _frequency, _resonance;
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double freqcorrect;
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double in1, in2, in3, in4;
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double out1, out2, out3, out4;
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public:
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float frequency() { return _frequency; }
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void frequency(float newFrequency) { _frequency = newFrequency; }
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float resonance() { return _resonance; }
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void resonance(float newResonance) { _resonance = newResonance; }
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void streamInit()
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{
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in1 = in2 = in3 = in4 = out1 = out2 = out3 = out4 = 0.0;
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}
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void calculateBlock(unsigned long samples)
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{
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freqcorrect = 1.16 / (double)(samplingRate / 2);
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for (unsigned int i=0; i < samples; i++)
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{
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double input = invalue[i];
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double fc = _frequency;
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double res = _resonance;
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double f = fc * freqcorrect;
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double fb = res * (1.0 - 0.15 * f * f);
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input -= out4 * fb;
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input *= 0.35013 * (f * f) * (f * f);
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out1 = input + 0.3 * in1 + (1 - f) * out1; // Pole 1
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in1 = input;
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out2 = out1 + 0.3 * in2 + (1 - f) * out2; // Pole 2
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in2 = out1;
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out3 = out2 + 0.3 * in3 + (1 - f) * out3; // Pole 3
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in3 = out2;
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out4 = out3 + 0.3 * in4 + (1 - f) * out4; // Pole 4
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in4 = out3;
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outvalue[i] = out4;
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}
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}
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};
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REGISTER_IMPLEMENTATION(Synth_MOOG_VCF_impl);
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