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#include "eq.h"
// Author: reduzio@gmail.com (C) 2006
#include "globals/error_macros.h"
#include "eq.h"
#include <math.h>
#define POW2(v) ((v) * (v))
#define SQRT12 0.7071067811865475244008443621048490
/* Helper */
static int solve_quadratic(double a, double b, double c, double *r1, double *r2) {
//solves quadractic and returns number of roots
double base = 2 * a;
if (base == 0.0f)
return 0;
double squared = b * b - 4 * a * c;
if (squared < 0.0)
return 0;
squared = sqrt(squared);
*r1 = (-b + squared) / base;
*r2 = (-b - squared) / base;
if (*r1 == *r2)
return 1;
else
return 2;
}
EQ::BandProcess::BandProcess() {
c1 = c2 = c3 = history.a1 = history.a2 = history.a3 = 0;
history.b1 = history.b2 = history.b3 = 0;
}
void EQ::recalculate_band_coefficients() {
#define BAND_LOG(m_f) (log((m_f)) / log(2.))
for (int i = 0; i < band.size(); i++) {
double octave_size;
double frq = band[i].freq;
if (i == 0) {
octave_size = BAND_LOG(band[1].freq) - BAND_LOG(frq);
} else if (i == (band.size() - 1)) {
octave_size = BAND_LOG(frq) - BAND_LOG(band[i - 1].freq);
} else {
double next = BAND_LOG(band[i + 1].freq) - BAND_LOG(frq);
double prev = BAND_LOG(frq) - BAND_LOG(band[i - 1].freq);
octave_size = (next + prev) / 2.0;
}
double frq_l = round(frq / pow(2.0, octave_size / 2.0));
double side_gain2 = POW2(SQRT12);
double th = 2.0 * M_PI * frq / mix_rate;
double th_l = 2.0 * M_PI * frq_l / mix_rate;
double c2a = side_gain2 * POW2(cos(th)) - 2.0 * side_gain2 * cos(th_l) * cos(th) + side_gain2 - POW2(sin(th_l));
double c2b = 2.0 * side_gain2 * POW2(cos(th_l)) + side_gain2 * POW2(cos(th)) - 2.0 * side_gain2 * cos(th_l) * cos(th) - side_gain2 + POW2(sin(th_l));
double c2c = 0.25 * side_gain2 * POW2(cos(th)) - 0.5 * side_gain2 * cos(th_l) * cos(th) + 0.25 * side_gain2 - 0.25 * POW2(sin(th_l));
//printf("band %i, precoefs = %f,%f,%f\n",i,c2a,c2b,c2c);
double r1, r2; //roots
int roots = solve_quadratic(c2a, c2b, c2c, &r1, &r2);
ERR_CONTINUE(roots == 0);
band[i].c1 = 2.0 * ((0.5 - r1) / 2.0);
band[i].c2 = 2.0 * r1;
band[i].c3 = 2.0 * (0.5 + r1) * cos(th);
//printf("band %i, coefs = %f,%f,%f\n",i,(float)bands[i].c1,(float)bands[i].c2,(float)bands[i].c3);
}
}
void EQ::set_preset_band_mode(Preset p_preset) {
band.clear();
#define PUSH_BANDS(m_bands) \
for (int i = 0; i < m_bands; i++) { \
Band b; \
b.freq = bands[i]; \
band.push_back(b); \
}
switch (p_preset) {
case PRESET_6_BANDS: {
static const double bands[] = { 32, 100, 320, 1e3, 3200, 10e3 };
PUSH_BANDS(6);
} break;
case PRESET_8_BANDS: {
static const double bands[] = { 32, 72, 192, 512, 1200, 3000, 7500, 16e3 };
PUSH_BANDS(8);
} break;
case PRESET_10_BANDS: {
static const double bands[] = { 31.25, 62.5, 125, 250, 500, 1e3, 2e3, 4e3, 8e3, 16e3 };
PUSH_BANDS(10);
} break;
case PRESET_21_BANDS: {
static const double bands[] = { 22, 32, 44, 63, 90, 125, 175, 250, 350, 500, 700, 1e3, 1400, 2e3, 2800, 4e3, 5600, 8e3, 11e3, 16e3, 22e3 };
PUSH_BANDS(21);
} break;
case PRESET_31_BANDS: {
static const double bands[] = { 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1e3, 1250, 1600, 2e3, 2500, 3150, 4e3, 5e3, 6300, 8e3, 10e3, 12500, 16e3, 20e3 };
PUSH_BANDS(31);
} break;
};
recalculate_band_coefficients();
}
int EQ::get_band_count() const {
return band.size();
}
float EQ::get_band_frequency(int p_band) {
ERR_FAIL_INDEX_V(p_band, band.size(), 0);
return band[p_band].freq;
}
void EQ::set_bands(const Vector<float> &p_bands) {
band.resize(p_bands.size());
for (int i = 0; i < p_bands.size(); i++) {
band[i].freq = p_bands[i];
}
recalculate_band_coefficients();
}
void EQ::set_mix_rate(float p_mix_rate) {
mix_rate = p_mix_rate;
recalculate_band_coefficients();
}
EQ::BandProcess EQ::get_band_processor(int p_band) const {
EQ::BandProcess band_proc;
ERR_FAIL_INDEX_V(p_band, band.size(), band_proc);
band_proc.c1 = band[p_band].c1;
band_proc.c2 = band[p_band].c2;
band_proc.c3 = band[p_band].c3;
return band_proc;
}
EQ::EQ() {
mix_rate = 44100;
}
EQ::~EQ() {
}
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