Java example source code file (SoftFilter.java)
The SoftFilter.java Java example source code/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package com.sun.media.sound;
/**
* Infinite impulse response (IIR) filter class.
*
* The filters where implemented and adapted using algorithms from musicdsp.org
* archive: 1-RC and C filter, Simple 2-pole LP LP and HP filter, biquad,
* tweaked butterworth RBJ Audio-EQ-Cookbook, EQ filter kookbook
*
* @author Karl Helgason
*/
public final class SoftFilter {
public final static int FILTERTYPE_LP6 = 0x00;
public final static int FILTERTYPE_LP12 = 0x01;
public final static int FILTERTYPE_HP12 = 0x11;
public final static int FILTERTYPE_BP12 = 0x21;
public final static int FILTERTYPE_NP12 = 0x31;
public final static int FILTERTYPE_LP24 = 0x03;
public final static int FILTERTYPE_HP24 = 0x13;
//
// 0x0 = 1st-order, 6 dB/oct
// 0x1 = 2nd-order, 12 dB/oct
// 0x2 = 3rd-order, 18 dB/oct
// 0x3 = 4th-order, 24 db/oct
//
// 0x00 = LP, Low Pass Filter
// 0x10 = HP, High Pass Filter
// 0x20 = BP, Band Pass Filter
// 0x30 = NP, Notch or Band Elimination Filter
//
private int filtertype = FILTERTYPE_LP6;
private final float samplerate;
private float x1;
private float x2;
private float y1;
private float y2;
private float xx1;
private float xx2;
private float yy1;
private float yy2;
private float a0;
private float a1;
private float a2;
private float b1;
private float b2;
private float q;
private float gain = 1;
private float wet = 0;
private float last_wet = 0;
private float last_a0;
private float last_a1;
private float last_a2;
private float last_b1;
private float last_b2;
private float last_q;
private float last_gain;
private boolean last_set = false;
private double cutoff = 44100;
private double resonancedB = 0;
private boolean dirty = true;
public SoftFilter(float samplerate) {
this.samplerate = samplerate;
dirty = true;
}
public void setFrequency(double cent) {
if (cutoff == cent)
return;
cutoff = cent;
dirty = true;
}
public void setResonance(double db) {
if (resonancedB == db)
return;
resonancedB = db;
dirty = true;
}
public void reset() {
dirty = true;
last_set = false;
x1 = 0;
x2 = 0;
y1 = 0;
y2 = 0;
xx1 = 0;
xx2 = 0;
yy1 = 0;
yy2 = 0;
wet = 0.0f;
gain = 1.0f;
a0 = 0;
a1 = 0;
a2 = 0;
b1 = 0;
b2 = 0;
}
public void setFilterType(int filtertype) {
this.filtertype = filtertype;
}
public void processAudio(SoftAudioBuffer sbuffer) {
if (filtertype == FILTERTYPE_LP6)
filter1(sbuffer);
if (filtertype == FILTERTYPE_LP12)
filter2(sbuffer);
if (filtertype == FILTERTYPE_HP12)
filter2(sbuffer);
if (filtertype == FILTERTYPE_BP12)
filter2(sbuffer);
if (filtertype == FILTERTYPE_NP12)
filter2(sbuffer);
if (filtertype == FILTERTYPE_LP24)
filter4(sbuffer);
if (filtertype == FILTERTYPE_HP24)
filter4(sbuffer);
}
public void filter4(SoftAudioBuffer sbuffer) {
float[] buffer = sbuffer.array();
if (dirty) {
filter2calc();
dirty = false;
}
if (!last_set) {
last_a0 = a0;
last_a1 = a1;
last_a2 = a2;
last_b1 = b1;
last_b2 = b2;
last_gain = gain;
last_wet = wet;
last_set = true;
}
if (wet > 0 || last_wet > 0) {
int len = buffer.length;
float a0 = this.last_a0;
float a1 = this.last_a1;
float a2 = this.last_a2;
float b1 = this.last_b1;
float b2 = this.last_b2;
float gain = this.last_gain;
float wet = this.last_wet;
float a0_delta = (this.a0 - this.last_a0) / len;
float a1_delta = (this.a1 - this.last_a1) / len;
float a2_delta = (this.a2 - this.last_a2) / len;
float b1_delta = (this.b1 - this.last_b1) / len;
float b2_delta = (this.b2 - this.last_b2) / len;
float gain_delta = (this.gain - this.last_gain) / len;
float wet_delta = (this.wet - this.last_wet) / len;
float x1 = this.x1;
float x2 = this.x2;
float y1 = this.y1;
float y2 = this.y2;
float xx1 = this.xx1;
float xx2 = this.xx2;
float yy1 = this.yy1;
float yy2 = this.yy2;
if (wet_delta != 0) {
for (int i = 0; i < len; i++) {
a0 += a0_delta;
a1 += a1_delta;
a2 += a2_delta;
b1 += b1_delta;
b2 += b2_delta;
gain += gain_delta;
wet += wet_delta;
float x = buffer[i];
float y = (a0*x + a1*x1 + a2*x2 - b1*y1 - b2*y2);
float xx = (y * gain) * wet + (x) * (1 - wet);
x2 = x1;
x1 = x;
y2 = y1;
y1 = y;
float yy = (a0*xx + a1*xx1 + a2*xx2 - b1*yy1 - b2*yy2);
buffer[i] = (yy * gain) * wet + (xx) * (1 - wet);
xx2 = xx1;
xx1 = xx;
yy2 = yy1;
yy1 = yy;
}
} else if (a0_delta == 0 && a1_delta == 0 && a2_delta == 0
&& b1_delta == 0 && b2_delta == 0) {
for (int i = 0; i < len; i++) {
float x = buffer[i];
float y = (a0*x + a1*x1 + a2*x2 - b1*y1 - b2*y2);
float xx = (y * gain) * wet + (x) * (1 - wet);
x2 = x1;
x1 = x;
y2 = y1;
y1 = y;
float yy = (a0*xx + a1*xx1 + a2*xx2 - b1*yy1 - b2*yy2);
buffer[i] = (yy * gain) * wet + (xx) * (1 - wet);
xx2 = xx1;
xx1 = xx;
yy2 = yy1;
yy1 = yy;
}
} else {
for (int i = 0; i < len; i++) {
a0 += a0_delta;
a1 += a1_delta;
a2 += a2_delta;
b1 += b1_delta;
b2 += b2_delta;
gain += gain_delta;
float x = buffer[i];
float y = (a0*x + a1*x1 + a2*x2 - b1*y1 - b2*y2);
float xx = (y * gain) * wet + (x) * (1 - wet);
x2 = x1;
x1 = x;
y2 = y1;
y1 = y;
float yy = (a0*xx + a1*xx1 + a2*xx2 - b1*yy1 - b2*yy2);
buffer[i] = (yy * gain) * wet + (xx) * (1 - wet);
xx2 = xx1;
xx1 = xx;
yy2 = yy1;
yy1 = yy;
}
}
if (Math.abs(x1) < 1.0E-8)
x1 = 0;
if (Math.abs(x2) < 1.0E-8)
x2 = 0;
if (Math.abs(y1) < 1.0E-8)
y1 = 0;
if (Math.abs(y2) < 1.0E-8)
y2 = 0;
this.x1 = x1;
this.x2 = x2;
this.y1 = y1;
this.y2 = y2;
this.xx1 = xx1;
this.xx2 = xx2;
this.yy1 = yy1;
this.yy2 = yy2;
}
this.last_a0 = this.a0;
this.last_a1 = this.a1;
this.last_a2 = this.a2;
this.last_b1 = this.b1;
this.last_b2 = this.b2;
this.last_gain = this.gain;
this.last_wet = this.wet;
}
private double sinh(double x) {
return (Math.exp(x) - Math.exp(-x)) * 0.5;
}
public void filter2calc() {
double resonancedB = this.resonancedB;
if (resonancedB < 0)
resonancedB = 0; // Negative dB are illegal.
if (resonancedB > 30)
resonancedB = 30; // At least 22.5 dB is needed.
if (filtertype == FILTERTYPE_LP24 || filtertype == FILTERTYPE_HP24)
resonancedB *= 0.6;
if (filtertype == FILTERTYPE_BP12) {
wet = 1;
double r = (cutoff / samplerate);
if (r > 0.45)
r = 0.45;
double bandwidth = Math.PI * Math.pow(10.0, -(resonancedB / 20));
double omega = 2 * Math.PI * r;
double cs = Math.cos(omega);
double sn = Math.sin(omega);
double alpha = sn * sinh((Math.log(2)*bandwidth*omega) / (sn * 2));
double b0 = alpha;
double b1 = 0;
double b2 = -alpha;
double a0 = 1 + alpha;
double a1 = -2 * cs;
double a2 = 1 - alpha;
double cf = 1.0 / a0;
this.b1 = (float) (a1 * cf);
this.b2 = (float) (a2 * cf);
this.a0 = (float) (b0 * cf);
this.a1 = (float) (b1 * cf);
this.a2 = (float) (b2 * cf);
}
if (filtertype == FILTERTYPE_NP12) {
wet = 1;
double r = (cutoff / samplerate);
if (r > 0.45)
r = 0.45;
double bandwidth = Math.PI * Math.pow(10.0, -(resonancedB / 20));
double omega = 2 * Math.PI * r;
double cs = Math.cos(omega);
double sn = Math.sin(omega);
double alpha = sn * sinh((Math.log(2)*bandwidth*omega) / (sn*2));
double b0 = 1;
double b1 = -2 * cs;
double b2 = 1;
double a0 = 1 + alpha;
double a1 = -2 * cs;
double a2 = 1 - alpha;
double cf = 1.0 / a0;
this.b1 = (float)(a1 * cf);
this.b2 = (float)(a2 * cf);
this.a0 = (float)(b0 * cf);
this.a1 = (float)(b1 * cf);
this.a2 = (float)(b2 * cf);
}
if (filtertype == FILTERTYPE_LP12 || filtertype == FILTERTYPE_LP24) {
double r = (cutoff / samplerate);
if (r > 0.45) {
if (wet == 0) {
if (resonancedB < 0.00001)
wet = 0.0f;
else
wet = 1.0f;
}
r = 0.45;
} else
wet = 1.0f;
double c = 1.0 / (Math.tan(Math.PI * r));
double csq = c * c;
double resonance = Math.pow(10.0, -(resonancedB / 20));
double q = Math.sqrt(2.0f) * resonance;
double a0 = 1.0 / (1.0 + (q * c) + (csq));
double a1 = 2.0 * a0;
double a2 = a0;
double b1 = (2.0 * a0) * (1.0 - csq);
double b2 = a0 * (1.0 - (q * c) + csq);
this.a0 = (float)a0;
this.a1 = (float)a1;
this.a2 = (float)a2;
this.b1 = (float)b1;
this.b2 = (float)b2;
}
if (filtertype == FILTERTYPE_HP12 || filtertype == FILTERTYPE_HP24) {
double r = (cutoff / samplerate);
if (r > 0.45)
r = 0.45;
if (r < 0.0001)
r = 0.0001;
wet = 1.0f;
double c = (Math.tan(Math.PI * (r)));
double csq = c * c;
double resonance = Math.pow(10.0, -(resonancedB / 20));
double q = Math.sqrt(2.0f) * resonance;
double a0 = 1.0 / (1.0 + (q * c) + (csq));
double a1 = -2.0 * a0;
double a2 = a0;
double b1 = (2.0 * a0) * (csq - 1.0);
double b2 = a0 * (1.0 - (q * c) + csq);
this.a0 = (float)a0;
this.a1 = (float)a1;
this.a2 = (float)a2;
this.b1 = (float)b1;
this.b2 = (float)b2;
}
}
public void filter2(SoftAudioBuffer sbuffer) {
float[] buffer = sbuffer.array();
if (dirty) {
filter2calc();
dirty = false;
}
if (!last_set) {
last_a0 = a0;
last_a1 = a1;
last_a2 = a2;
last_b1 = b1;
last_b2 = b2;
last_q = q;
last_gain = gain;
last_wet = wet;
last_set = true;
}
if (wet > 0 || last_wet > 0) {
int len = buffer.length;
float a0 = this.last_a0;
float a1 = this.last_a1;
float a2 = this.last_a2;
float b1 = this.last_b1;
float b2 = this.last_b2;
float gain = this.last_gain;
float wet = this.last_wet;
float a0_delta = (this.a0 - this.last_a0) / len;
float a1_delta = (this.a1 - this.last_a1) / len;
float a2_delta = (this.a2 - this.last_a2) / len;
float b1_delta = (this.b1 - this.last_b1) / len;
float b2_delta = (this.b2 - this.last_b2) / len;
float gain_delta = (this.gain - this.last_gain) / len;
float wet_delta = (this.wet - this.last_wet) / len;
float x1 = this.x1;
float x2 = this.x2;
float y1 = this.y1;
float y2 = this.y2;
if (wet_delta != 0) {
for (int i = 0; i < len; i++) {
a0 += a0_delta;
a1 += a1_delta;
a2 += a2_delta;
b1 += b1_delta;
b2 += b2_delta;
gain += gain_delta;
wet += wet_delta;
float x = buffer[i];
float y = (a0*x + a1*x1 + a2*x2 - b1*y1 - b2*y2);
buffer[i] = (y * gain) * wet + (x) * (1 - wet);
x2 = x1;
x1 = x;
y2 = y1;
y1 = y;
}
} else if (a0_delta == 0 && a1_delta == 0 && a2_delta == 0
&& b1_delta == 0 && b2_delta == 0) {
for (int i = 0; i < len; i++) {
float x = buffer[i];
float y = (a0*x + a1*x1 + a2*x2 - b1*y1 - b2*y2);
buffer[i] = y * gain;
x2 = x1;
x1 = x;
y2 = y1;
y1 = y;
}
} else {
for (int i = 0; i < len; i++) {
a0 += a0_delta;
a1 += a1_delta;
a2 += a2_delta;
b1 += b1_delta;
b2 += b2_delta;
gain += gain_delta;
float x = buffer[i];
float y = (a0*x + a1*x1 + a2*x2 - b1*y1 - b2*y2);
buffer[i] = y * gain;
x2 = x1;
x1 = x;
y2 = y1;
y1 = y;
}
}
if (Math.abs(x1) < 1.0E-8)
x1 = 0;
if (Math.abs(x2) < 1.0E-8)
x2 = 0;
if (Math.abs(y1) < 1.0E-8)
y1 = 0;
if (Math.abs(y2) < 1.0E-8)
y2 = 0;
this.x1 = x1;
this.x2 = x2;
this.y1 = y1;
this.y2 = y2;
}
this.last_a0 = this.a0;
this.last_a1 = this.a1;
this.last_a2 = this.a2;
this.last_b1 = this.b1;
this.last_b2 = this.b2;
this.last_q = this.q;
this.last_gain = this.gain;
this.last_wet = this.wet;
}
public void filter1calc() {
if (cutoff < 120)
cutoff = 120;
double c = (7.0 / 6.0) * Math.PI * 2 * cutoff / samplerate;
if (c > 1)
c = 1;
a0 = (float)(Math.sqrt(1 - Math.cos(c)) * Math.sqrt(0.5 * Math.PI));
if (resonancedB < 0)
resonancedB = 0;
if (resonancedB > 20)
resonancedB = 20;
q = (float)(Math.sqrt(0.5) * Math.pow(10.0, -(resonancedB / 20)));
gain = (float)Math.pow(10, -((resonancedB)) / 40.0);
if (wet == 0.0f)
if (resonancedB > 0.00001 || c < 0.9999999)
wet = 1.0f;
}
public void filter1(SoftAudioBuffer sbuffer) {
if (dirty) {
filter1calc();
dirty = false;
}
if (!last_set) {
last_a0 = a0;
last_q = q;
last_gain = gain;
last_wet = wet;
last_set = true;
}
if (wet > 0 || last_wet > 0) {
float[] buffer = sbuffer.array();
int len = buffer.length;
float a0 = this.last_a0;
float q = this.last_q;
float gain = this.last_gain;
float wet = this.last_wet;
float a0_delta = (this.a0 - this.last_a0) / len;
float q_delta = (this.q - this.last_q) / len;
float gain_delta = (this.gain - this.last_gain) / len;
float wet_delta = (this.wet - this.last_wet) / len;
float y2 = this.y2;
float y1 = this.y1;
if (wet_delta != 0) {
for (int i = 0; i < len; i++) {
a0 += a0_delta;
q += q_delta;
gain += gain_delta;
wet += wet_delta;
float ga0 = (1 - q * a0);
y1 = ga0 * y1 + (a0) * (buffer[i] - y2);
y2 = ga0 * y2 + (a0) * y1;
buffer[i] = y2 * gain * wet + buffer[i] * (1 - wet);
}
} else if (a0_delta == 0 && q_delta == 0) {
float ga0 = (1 - q * a0);
for (int i = 0; i < len; i++) {
y1 = ga0 * y1 + (a0) * (buffer[i] - y2);
y2 = ga0 * y2 + (a0) * y1;
buffer[i] = y2 * gain;
}
} else {
for (int i = 0; i < len; i++) {
a0 += a0_delta;
q += q_delta;
gain += gain_delta;
float ga0 = (1 - q * a0);
y1 = ga0 * y1 + (a0) * (buffer[i] - y2);
y2 = ga0 * y2 + (a0) * y1;
buffer[i] = y2 * gain;
}
}
if (Math.abs(y2) < 1.0E-8)
y2 = 0;
if (Math.abs(y1) < 1.0E-8)
y1 = 0;
this.y2 = y2;
this.y1 = y1;
}
this.last_a0 = this.a0;
this.last_q = this.q;
this.last_gain = this.gain;
this.last_wet = this.wet;
}
}
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