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/*
* Schism Tracker - a cross-platform Impulse Tracker clone
* copyright (c) 2003-2005 Storlek <storlek@rigelseven.com>
* copyright (c) 2005-2008 Mrs. Brisby <mrs.brisby@nimh.org>
* copyright (c) 2009 Storlek & Mrs. Brisby
* copyright (c) 2010-2012 Storlek
* URL: http://schismtracker.org/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "sndfile.h"
#include "cmixer.h"
#include <math.h>
#define EQ_BANDWIDTH 2.0
#define EQ_ZERO 0.000001
typedef struct {
float a0, a1, a2, b1, b2;
float x1, x2, y1, y2;
float gain, center_frequency;
int enabled;
} eq_band;
//static REAL f2ic = (REAL)(1 << 28);
//static REAL i2fc = (REAL)(1.0 / (1 << 28));
static eq_band eq[MAX_EQ_BANDS * 2] =
{
// Default: Flat EQ
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 120, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 600, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1200, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3000, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6000, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 10000, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 120, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 600, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1200, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3000, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6000, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 10000, 0},
};
static void eq_filter(eq_band *pbs, float *pbuffer, unsigned int count)
{
for (unsigned int i = 0; i < count; i++) {
float x = pbuffer[i];
float y = pbs->a1 * pbs->x1 +
pbs->a2 * pbs->x2 +
pbs->a0 * x +
pbs->b1 * pbs->y1 +
pbs->b2 * pbs->y2;
pbs->x2 = pbs->x1;
pbs->y2 = pbs->y1;
pbs->x1 = x;
pbuffer[i] = y;
pbs->y1 = y;
}
}
void eq_mono(song_t *csf, int *buffer, unsigned int count)
{
mono_mix_to_float(buffer, csf->mix_buffer_float, count);
for (unsigned int b = 0; b < MAX_EQ_BANDS; b++)
{
if (eq[b].enabled && eq[b].gain != 1.0f)
eq_filter(&eq[b], csf->mix_buffer_float, count);
}
float_to_mono_mix(csf->mix_buffer_float, buffer, count);
}
// XXX: I rolled the two loops into one. Make sure this works.
void eq_stereo(song_t *csf, int *buffer, unsigned int count)
{
stereo_mix_to_float(buffer, csf->mix_buffer_float, csf->mix_buffer_float + MIXBUFFERSIZE, count);
for (unsigned int b = 0; b < MAX_EQ_BANDS; b++) {
int br = b + MAX_EQ_BANDS;
// Left band
if (eq[b].enabled && eq[b].gain != 1.0f)
eq_filter(&eq[b], csf->mix_buffer_float, count);
// Right band
if (eq[br].enabled && eq[br].gain != 1.0f)
eq_filter(&eq[br], csf->mix_buffer_float + MIXBUFFERSIZE, count);
}
float_to_stereo_mix(csf->mix_buffer_float, csf->mix_buffer_float + MIXBUFFERSIZE, buffer, count);
}
void initialize_eq(int reset, float freq)
{
//float fMixingFreq = (REAL)mix_frequency;
// Gain = 0.5 (-6dB) .. 2 (+6dB)
for (unsigned int band = 0; band < MAX_EQ_BANDS * 2; band++) {
float k, k2, r, f;
float v0, v1;
int b = reset;
if (!eq[band].enabled) {
eq[band].a0 = 0;
eq[band].a1 = 0;
eq[band].a2 = 0;
eq[band].b1 = 0;
eq[band].b2 = 0;
eq[band].x1 = 0;
eq[band].x2 = 0;
eq[band].y1 = 0;
eq[band].y2 = 0;
continue;
}
f = eq[band].center_frequency / freq;
if (f > 0.45f)
eq[band].gain = 1;
//if (f > 0.25)
// f = 0.25;
//k = tan(PI * f);
k = f * 3.141592654f;
k = k + k * f;
//if (k > (float) 0.707)
// k = (float) 0.707;
k2 = k*k;
v0 = eq[band].gain;
v1 = 1;
if (eq[band].gain < 1.0) {
v0 *= 0.5f / EQ_BANDWIDTH;
v1 *= 0.5f / EQ_BANDWIDTH;
}
else {
v0 *= 1.0f / EQ_BANDWIDTH;
v1 *= 1.0f / EQ_BANDWIDTH;
}
r = (1 + v0 * k + k2) / (1 + v1 * k + k2);
if (r != eq[band].a0) {
eq[band].a0 = r;
b = 1;
}
r = 2 * (k2 - 1) / (1 + v1 * k + k2);
if (r != eq[band].a1) {
eq[band].a1 = r;
b = 1;
}
r = (1 - v0 * k + k2) / (1 + v1 * k + k2);
if (r != eq[band].a2) {
eq[band].a2 = r;
b = 1;
}
r = -2 * (k2 - 1) / (1 + v1 * k + k2);
if (r != eq[band].b1) {
eq[band].b1 = r;
b = 1;
}
r = -(1 - v1 * k + k2) / (1 + v1 * k + k2);
if (r != eq[band].b2) {
eq[band].b2 = r;
b = 1;
}
if (b) {
eq[band].x1 = 0;
eq[band].x2 = 0;
eq[band].y1 = 0;
eq[band].y2 = 0;
}
}
}
void set_eq_gains(const unsigned int *gainbuff, unsigned int gains, const unsigned int *freqs,
int reset, int mix_freq)
{
for (unsigned int i = 0; i < MAX_EQ_BANDS; i++) {
float g, f = 0;
if (i < gains) {
unsigned int n = gainbuff[i];
//if (n > 32)
// n = 32;
g = 1.0 + (((double) n) / 64.0);
if (freqs)
f = (float)(int) freqs[i];
}
else {
g = 1;
}
eq[i].gain =
eq[i + MAX_EQ_BANDS].gain = g;
eq[i].center_frequency =
eq[i + MAX_EQ_BANDS].center_frequency = f;
/* don't enable bands outside... */
if (f > 20.0f &&
i < gains) {
eq[i].enabled =
eq[i + MAX_EQ_BANDS].enabled = 1;
}
else {
eq[i].enabled =
eq[i + MAX_EQ_BANDS].enabled = 0;
}
}
initialize_eq(reset, mix_freq);
}
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