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SVF class

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This commit is contained in:
Gordon JC Pearce 2024-08-29 23:15:10 +01:00
parent 43f6d53a56
commit 5e18d3437f
2 changed files with 60 additions and 77 deletions
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93
plugin/barrverb.cpp
View File

@ -17,8 +17,38 @@
*/
#include "barrverb.hpp"
#include "rom.h"
SVF::SVF(float cutoff = 0, float q = 0, float samplerate = 0) {
z1 = z2 = 0;
setFreq(cutoff, q, samplerate);
}
void SVF::setFreq(float cutoff, float q, float samplerate) {
z1 = z2 = 0;
printf("called with %f %f %f\n", cutoff, q, samplerate);
w = 2 * tan(3.14159 * (cutoff / samplerate));
a = w / q;
b = w * w;
// corrected SVF params, per Fons Adriaensen
c1 = (a + b) / (1 + a / 2 + b / 4);
c2 = b / (a + b);
d0 = c1 * c2 / 4;
printf("c1 %f c2 %f d0 %f\n", c1, c2, d0);
}
inline float SVF::lpStep(float in) {
x = in - z1 - z2;
z2 += c2 * z1;
z1 += c1 * x;
return d0 * x + z2;
}
START_NAMESPACE_DISTRHO
BarrVerb::BarrVerb() : Plugin(kParameterCount, 64, 0) { // one parameter, 64 programs, no states
@ -28,52 +58,8 @@ BarrVerb::BarrVerb() : Plugin(kParameterCount, 64, 0) { // one parameter, 64 pr
bzero(lowpass, sizeof(float) * getBufferSize());
bzero(ram, sizeof(int16_t) * 16384);
/*
// calculate SVF params
// hardcoded values for now
float fc = 5019;
float F = fc / 48000; // assume 48kHz
float w = 2 * tan(3.14159 * F);
float a = w / 0.7845; // 1dB Chebyshev, 2-pole
float b = w * w;
// "corrected" SVF params, per Fons Adriaensen
c1_1 = (a + b) / (1 + a / 2 + b / 4);
c2_1 = b / (a + b);
d0_1 = c1_1 * c2_1 / 4;
fc = 9433;
F = fc / 48000; // assume 48kHz
w = 2 * tan(3.14159 * F);
a = w / 3.5594; // 1dB Chebyshev, 2-pole
b = w * w;
c1_2 = (a + b) / (1 + a / 2 + b / 4);
c2_2 = b / (a + b);
d0_2 = c1_2 * c2_2 / 4;*/
// calculate SVF params
// hardcoded values for now
float fc = 10000;
float F = fc / 48000; // assume 48kHz
float w = 2 * tan(3.14159 * F);
float a = w / 0.5412; // Butterworth 4-pole first stage
float b = w * w;
// "corrected" SVF params, per Fons Adriaensen
c1_1 = (a + b) / (1 + a / 2 + b / 4);
c2_1 = b / (a + b);
d0_1 = c1_1 * c2_1 / 4;
fc = 10000;
F = fc / 48000; // assume 48kHz
w = 2 * tan(3.14159 * F);
a = w / 1.3065; // Butterworth 4-pole second stage
b = w * w;
c1_2 = (a + b) / (1 + a / 2 + b / 4);
c2_2 = b / (a + b);
d0_2 = c1_2 * c2_2 / 4;
f1.setFreq(5916, .6572, getSampleRate());
f2.setFreq(9458, 2.536, getSampleRate());
}
// Initialisation functions
@ -114,7 +100,6 @@ void BarrVerb::initAudioPort(bool input, uint32_t index, AudioPort &port) {
}
void BarrVerb::initProgramName(uint32_t index, String &programName) {
programName = prog_name[index & 0x3f].c_str();
}
@ -138,22 +123,11 @@ void BarrVerb::deactivate() {
void BarrVerb::run(const float **inputs, float **outputs, uint32_t frames) {
// actual effects here
float x;
uint16_t opcode;
for (uint32_t i = 0; i < frames; i++) {
// smash to mono
lowpass[i] = (inputs[0][i] + inputs[1][i]) / 2;
// 10kHz lowpass filter, 2x oversampling
x = lowpass[i] - in_z1 - in_z2;
in_z2 += c2_1 * in_z1;
in_z1 += c1_1 * x;
x = (d0_1 * x + in_z2) - in_z12 - in_z22;
in_z22 += c2_2 * in_z12;
in_z12 += c1_2 * x;
lowpass[i] = d0_2 * x + in_z22;
lowpass[i] = f2.lpStep(f1.lpStep((inputs[0][i] + inputs[1][i]) / 2));
}
// now run the DSP
@ -186,7 +160,6 @@ void BarrVerb::run(const float **inputs, float **outputs, uint32_t frames) {
if (ai > 2047) ai = 2047;
if (ai < -2047) ai = -2047;
if (step == 0x00) {
// load RAM from ADC
ram[ptr] = (int)(lowpass[i] * 2048);

18
plugin/barrverb.hpp
View File

@ -21,6 +21,18 @@
#include "DistrhoPlugin.hpp"
class SVF {
public:
SVF(float cutoff, float q, float samplerate);
void setFreq(float cutoff, float q, float samplerate);
float lpStep(float in);
private:
float w, a, b;
float c1, c2, d0;
float z1, z2, x;
};
START_NAMESPACE_DISTRHO
class BarrVerb : public Plugin {
@ -49,19 +61,17 @@ class BarrVerb : public Plugin {
void setParameterValue(uint32_t index, float value) override;
float getParameterValue(uint32_t index) const override;
void initProgramName(uint32_t index, String &programName) override;
void loadProgram(uint32_t index) override;
// Processing
void activate() override;
void deactivate() override;
void run(const float **inputs, float **outputs, uint32_t frames) override;
private:
float c1_1, c2_1, d0_1, c1_2, c2_2, d0_2, in_z1, in_z2, in_z12,in_z22, out_z1, out_z2;
// float c1_1, c2_1, d0_1, c1_2, c2_2, d0_2, in_z1, in_z2, in_z12,in_z22, out_z1, out_z2;
SVF f1, f2;
int16_t ai, li, acc;
uint16_t ptr;