219 lines
4.2 KiB
C++
219 lines
4.2 KiB
C++
//
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// C++ Interface: eq
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//
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// Description:
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//
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//
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// Author: reduzio@gmail.com (C) 2006
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//
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// Copyright: See COPYING file that comes with this distribution
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//
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//
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#include "eq.h"
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#include <math.h>
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#include "error_macros.h"
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#define POW2(v) ((v)*(v))
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/* Helper */
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static int solve_quadratic(double a,double b,double c,double *r1, double *r2) {
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//solves quadractic and returns number of roots
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double base=2*a;
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if (base == 0.0f)
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return 0;
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double squared=b*b-4*a*c;
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if (squared<0.0)
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return 0;
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squared=sqrt(squared);
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*r1=(-b+squared)/base;
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*r2=(-b-squared)/base;
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if (*r1==*r2)
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return 1;
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else
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return 2;
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}
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EQ::BandProcess::BandProcess() {
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c1=c2=c3=history.a1=history.a2=history.a3=0;
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history.b1=history.b2=history.b3=0;
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}
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void EQ::recalculate_band_coefficients() {
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#define BAND_LOG( m_f ) ( log((m_f)) / log(2) )
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for (int i=0;i<band.size();i++) {
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double octave_size;
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double frq=band[i].freq;
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if (i==0) {
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octave_size=BAND_LOG(band[1].freq)-BAND_LOG(frq);
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} else if (i==(band.size()-1)) {
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octave_size=BAND_LOG(frq)-BAND_LOG(band[i-1].freq);
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} else {
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double next=BAND_LOG(band[i+1].freq)-BAND_LOG(frq);
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double prev=BAND_LOG(frq)-BAND_LOG(band[i-1].freq);
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octave_size=(next+prev)/2.0;
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}
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double frq_l=round(frq/pow(2.0,octave_size/2.0));
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double side_gain2=POW2(1.0/M_SQRT2);
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double th=2.0*M_PI*frq/mix_rate;
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double th_l=2.0*M_PI*frq_l/mix_rate;
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double c2a=side_gain2 * POW2(cos(th))
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- 2.0 * side_gain2 * cos(th_l) * cos(th)
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+ side_gain2
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- POW2(sin(th_l));
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double c2b=2.0 * side_gain2 * POW2(cos(th_l))
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+ side_gain2 * POW2(cos(th))
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- 2.0 * side_gain2 * cos(th_l) * cos(th)
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- side_gain2
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+ POW2(sin(th_l));
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double c2c=0.25 * side_gain2 * POW2(cos(th))
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- 0.5 * side_gain2 * cos(th_l) * cos(th)
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+ 0.25 * side_gain2
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- 0.25 * POW2(sin(th_l));
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//printf("band %i, precoefs = %f,%f,%f\n",i,c2a,c2b,c2c);
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double r1,r2; //roots
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int roots=solve_quadratic(c2a,c2b,c2c,&r1,&r2);
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ERR_CONTINUE( roots==0 );
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band[i].c1=2.0 * ((0.5-r1)/2.0);
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band[i].c2=2.0 * r1;
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band[i].c3=2.0 * (0.5+r1) * cos(th);
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//printf("band %i, coefs = %f,%f,%f\n",i,(float)bands[i].c1,(float)bands[i].c2,(float)bands[i].c3);
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}
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}
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void EQ::set_preset_band_mode(Preset p_preset) {
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band.clear();
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#define PUSH_BANDS(m_bands) \
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for (int i=0;i<m_bands;i++) { \
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Band b; \
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b.freq=bands[i];\
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band.push_back(b);\
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}
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switch (p_preset) {
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case PRESET_6_BANDS: {
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static const double bands[] = { 32 , 100 , 320 , 1e3, 3200, 10e3 };
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PUSH_BANDS(6);
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} break;
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case PRESET_8_BANDS: {
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static const double bands[] = { 32,72,192,512,1200,3000,7500,16e3 };
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PUSH_BANDS(8);
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} break;
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case PRESET_10_BANDS: {
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static const double bands[] = { 31.25, 62.5, 125 , 250 , 500 , 1e3, 2e3, 4e3, 8e3, 16e3 };
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PUSH_BANDS(10);
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} break;
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case PRESET_21_BANDS: {
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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 };
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PUSH_BANDS(21);
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} break;
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case PRESET_31_BANDS: {
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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 };
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PUSH_BANDS(31);
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} break;
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};
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recalculate_band_coefficients();
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}
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int EQ::get_band_count() const {
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return band.size();
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}
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float EQ::get_band_frequency(int p_band) {
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ERR_FAIL_INDEX_V(p_band,band.size(),0);
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return band[p_band].freq;
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}
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void EQ::set_bands(const Vector<float>& p_bands) {
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band.resize(p_bands.size());
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for (int i=0;i<p_bands.size();i++) {
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band[i].freq=p_bands[i];
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}
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recalculate_band_coefficients();
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}
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void EQ::set_mix_rate(float p_mix_rate) {
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mix_rate=p_mix_rate;
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recalculate_band_coefficients();
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}
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EQ::BandProcess EQ::get_band_processor(int p_band) const {
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EQ::BandProcess band_proc;
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ERR_FAIL_INDEX_V(p_band,band.size(),band_proc);
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band_proc.c1=band[p_band].c1;
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band_proc.c2=band[p_band].c2;
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band_proc.c3=band[p_band].c3;
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return band_proc;
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}
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EQ::EQ()
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{
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mix_rate=44100;
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}
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EQ::~EQ()
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{
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}
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