1 files changed, 91 insertions, 0 deletions
diff --git a/arts/modules/synth/synth_moog_vcf_impl.cc b/arts/modules/synth/synth_moog_vcf_impl.cc
new file mode 100644
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+++ b/arts/modules/synth/synth_moog_vcf_impl.cc
@@ -0,0 +1,91 @@
+/*
+
+	Copyright (C) 2000 Jeff Tranter
+			           tranter@pobox.com
+
+			  (C) 1999 Stefan Westerfeld
+                       stefan@space.twc.de
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+    */
+
+#include "artsmodulessynth.h"
+#include "stdsynthmodule.h"
+
+using namespace Arts;
+
+/*
+Try this. It's a really nice 4pole. Very Moog like.
+
+in[x] and out[x] are member variables, init to 0.0
+the controls:
+
+fc = cutoff, nearly linear [0,1] -> [0, fs/2]
+res = resonance [0, 4] -> [no resonance, self-oscillation]
+*/
+
+class Synth_MOOG_VCF_impl : virtual public Synth_MOOG_VCF_skel,
+							virtual public StdSynthModule
+{
+protected:
+	float _frequency, _resonance;
+	double freqcorrect;
+	double in1, in2, in3, in4;
+	double out1, out2, out3, out4;
+
+public:
+	float frequency() { return _frequency; }
+	void frequency(float newFrequency) { _frequency = newFrequency; }
+
+	float resonance() { return _resonance; }
+	void resonance(float newResonance) { _resonance = newResonance; }
+
+	void streamInit()
+	{
+		in1 = in2 = in3 = in4 = out1 = out2 = out3 = out4 = 0.0;
+	}
+	
+	void calculateBlock(unsigned long samples)
+	{
+		freqcorrect = 1.16 / (double)(samplingRate / 2);
+
+		for	(unsigned int i=0; i < samples; i++)
+		{
+			double input = invalue[i];
+			double fc = _frequency;
+			double res = _resonance;
+			double f = fc * freqcorrect;
+			double fb = res * (1.0 - 0.15 * f * f);
+
+			input -= out4 * fb;
+			input *= 0.35013 * (f * f) * (f * f);
+			
+			out1 = input + 0.3 * in1 + (1 - f) * out1; // Pole 1
+			in1  = input;
+			out2 = out1 + 0.3 * in2 + (1 - f) * out2;  // Pole 2
+			in2  = out1;
+			out3 = out2 + 0.3 * in3 + (1 - f) * out3;  // Pole 3
+			in3  = out2;
+			out4 = out3 + 0.3 * in4 + (1 - f) * out4;  // Pole 4
+			in4  = out3;
+			
+			outvalue[i] = out4;
+		}
+	}
+
+};
+
+REGISTER_IMPLEMENTATION(Synth_MOOG_VCF_impl);