virtualx-engine/servers/audio/effects/eq.cpp

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//
// C++ Interface: eq
//
// Description:
//
//
// Author: reduzio@gmail.com (C) 2006
//
// Copyright: See COPYING file that comes with this distribution
//
//
#include "eq.h"
#include <math.h>
#include "error_macros.h"
#include "math_funcs.h"
#define POW2(v) ((v)*(v))
/* 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(Math_SQRT12);
double th=2.0*Math_PI*frq/mix_rate;
double th_l=2.0*Math_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()
{
}