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Parallel resonance

This commit is contained in:
yaw-man 2022-08-24 21:54:31 -03:00
parent 7c36a8bf98
commit 54bee81c43
2 changed files with 52 additions and 53 deletions
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49
src/yaw-vowel/filter.cpp
View File

@ -5,20 +5,55 @@ void Resonator::clear()
xp = xpp = yp = ypp = 0;
}
void Resonator::process(float* output, const float* const input, uint32_t frames)
inline float Resonator::process(float x)
{
for(uint32_t i = 0; i < frames; ++i){
float x = static_cast<float>(input[i] * scale);
float y = x - xpp - app * ypp + ap * yp;
output[i] = y;
// Apply biquad filter.
float y = scale * x - xpp - app * ypp + ap * yp;
// Update biquad memory.
xpp = xp;
xp = x;
ypp = yp;
yp = y;
}
return y;
}
void Resonator::set(double _app, double _ap, double _scale)
{
app = _app; ap = _ap; scale = _scale;
app = _app;
ap = _ap;
scale = _scale;
}
Filter::Filter(){};
void Filter::process(float **outputs, const float **inputs, uint32_t frames)
{
for (uint chn = 0; chn < 2; ++chn)
{
for (auto &r : res[chn])
{
for (uint32_t j = 0; j < frames; ++j)
{
outputs[chn][j] += r.process(inputs[chn][j]);
}
}
}
}
// Compute filter coefficients from
// frequency as a proportion of the sample rate
// REMEMBER: THAT'S DOUBLE THE Nyquist RATE, dummy
// and resonance in [0, 1]
void Filter::set(double x, double y, double p)
{
double r = p * 0.049 + 0.95; // Filter unstable at r = 1.
double app = r * r;
double xap = (1.0 + r * r) * cos(M_PI * x);
double yap = (1.0 + r * r) * cos(M_PI * y);
double scale = sqrt(0.5 - 0.5 * r * r);
for (auto &channelFilter : res)
{
channelFilter[0].set(app, xap, scale);
channelFilter[1].set(app, yap, scale);
}
}

46
src/yaw-vowel/filter.h
View File

@ -8,7 +8,7 @@ public:
Resonator():
xp(0), xpp(0), yp(0), ypp(0), app(0), ap(0), scale(1){};
void process(float *output, const float *const input, uint32_t frames);
inline float process(float x);
void clear();
void set(double _app, double _ap, double _scale);
@ -25,46 +25,10 @@ private:
class Filter
{
public:
Filter(){};
void process(float **outputs, const float **inputs, uint32_t frames)
{
for (uint chn = 0; chn < 2; ++chn)
{
for (uint32_t j = 0; j < frames; ++j)
{
outputs[chn][j] = inputs[chn][j];
}
for (auto& r : res[chn])
{
r.process(outputs[chn], outputs[chn], frames);
}
}
}
//Compute filter coefficients from
//frequency as a proportion of the sample rate
//REMEMBER: THAT'S DOUBLE THE Nyquist RATE, dummy
//and resonance in [0, 1]
void set(double x, double y, double p)
{
double r = p * 0.99;
double app = r * r;
double xap = (1.0 + r * r) * cos(M_PI * x);
double yap = (1.0 + r * r) * cos(M_PI * y);
double scale = sqrt(0.5 - 0.5 * r * r);
for (auto& channelFilter : res)
{
channelFilter[0].set(app, xap, scale);
channelFilter[1].set(app, xap, scale);
channelFilter[2].set(app, yap, scale);
channelFilter[3].set(app, yap, scale);
}
}
Filter();
void process(float **outputs, const float **inputs, uint32_t frames);
void set(double x, double y, double p);
private:
std::array<std::array<Resonator, 4>, 2> res;
std::array<std::array<Resonator, 2>, 2> res;
};