1 /*
2 * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package com.sun.media.sound;
27
28 /**
29 * A simple look-ahead volume limiter with very fast attack and fast release.
30 * This filter is used for preventing clipping.
31 *
32 * @author Karl Helgason
33 */
34 public final class SoftLimiter implements SoftAudioProcessor {
35
36 float lastmax = 0;
37 float gain = 1;
38 float[] temp_bufferL;
39 float[] temp_bufferR;
40 boolean mix = false;
41 SoftAudioBuffer bufferL;
42 SoftAudioBuffer bufferR;
43 SoftAudioBuffer bufferLout;
44 SoftAudioBuffer bufferRout;
45 float controlrate;
46
47 @Override
48 public void init(float samplerate, float controlrate) {
49 this.controlrate = controlrate;
50 }
51
52 @Override
53 public void setInput(int pin, SoftAudioBuffer input) {
54 if (pin == 0)
55 bufferL = input;
56 if (pin == 1)
57 bufferR = input;
58 }
59
60 @Override
61 public void setOutput(int pin, SoftAudioBuffer output) {
62 if (pin == 0)
63 bufferLout = output;
64 if (pin == 1)
65 bufferRout = output;
66 }
67
68 @Override
69 public void setMixMode(boolean mix) {
70 this.mix = mix;
71 }
72
73 @Override
74 public void globalParameterControlChange(int[] slothpath, long param,
75 long value) {
76 }
77
78 double silentcounter = 0;
79
80 @Override
81 public void processAudio() {
82 if (this.bufferL.isSilent()
83 && (this.bufferR == null || this.bufferR.isSilent())) {
84 silentcounter += 1 / controlrate;
85
86 if (silentcounter > 60) {
87 if (!mix) {
88 bufferLout.clear();
89 if (bufferRout != null) bufferRout.clear();
90 }
91 return;
92 }
93 } else
94 silentcounter = 0;
95
96 float[] bufferL = this.bufferL.array();
97 float[] bufferR = this.bufferR == null ? null : this.bufferR.array();
98 float[] bufferLout = this.bufferLout.array();
99 float[] bufferRout = this.bufferRout == null
100 ? null : this.bufferRout.array();
101
102 if (temp_bufferL == null || temp_bufferL.length < bufferL.length)
103 temp_bufferL = new float[bufferL.length];
104 if (bufferR != null)
105 if (temp_bufferR == null || temp_bufferR.length < bufferR.length)
106 temp_bufferR = new float[bufferR.length];
107
108 float max = 0;
109 int len = bufferL.length;
110
111 if (bufferR == null) {
112 for (int i = 0; i < len; i++) {
113 if (bufferL[i] > max)
114 max = bufferL[i];
115 if (-bufferL[i] > max)
116 max = -bufferL[i];
117 }
118 } else {
119 for (int i = 0; i < len; i++) {
120 if (bufferL[i] > max)
121 max = bufferL[i];
122 if (bufferR[i] > max)
123 max = bufferR[i];
124 if (-bufferL[i] > max)
125 max = -bufferL[i];
126 if (-bufferR[i] > max)
127 max = -bufferR[i];
128 }
129 }
130
131 float lmax = lastmax;
132 lastmax = max;
133 if (lmax > max)
134 max = lmax;
135
136 float newgain = 1;
137 if (max > 0.99f)
138 newgain = 0.99f / max;
139 else
140 newgain = 1;
141
142 if (newgain > gain)
143 newgain = (newgain + gain * 9) / 10f;
144
145 float gaindelta = (newgain - gain) / len;
146 if (mix) {
147 if (bufferR == null) {
148 for (int i = 0; i < len; i++) {
149 gain += gaindelta;
150 float bL = bufferL[i];
151 float tL = temp_bufferL[i];
152 temp_bufferL[i] = bL;
153 bufferLout[i] += tL * gain;
154 }
155 } else {
156 for (int i = 0; i < len; i++) {
157 gain += gaindelta;
158 float bL = bufferL[i];
159 float bR = bufferR[i];
160 float tL = temp_bufferL[i];
161 float tR = temp_bufferR[i];
162 temp_bufferL[i] = bL;
163 temp_bufferR[i] = bR;
164 bufferLout[i] += tL * gain;
165 bufferRout[i] += tR * gain;
166 }
167 }
168
169 } else {
170 if (bufferR == null) {
171 for (int i = 0; i < len; i++) {
172 gain += gaindelta;
173 float bL = bufferL[i];
174 float tL = temp_bufferL[i];
175 temp_bufferL[i] = bL;
176 bufferLout[i] = tL * gain;
177 }
178 } else {
179 for (int i = 0; i < len; i++) {
180 gain += gaindelta;
181 float bL = bufferL[i];
182 float bR = bufferR[i];
183 float tL = temp_bufferL[i];
184 float tR = temp_bufferR[i];
185 temp_bufferL[i] = bL;
186 temp_bufferR[i] = bR;
187 bufferLout[i] = tL * gain;
188 bufferRout[i] = tR * gain;
189 }
190 }
191
192 }
193 gain = newgain;
194 }
195
196 @Override
197 public void processControlLogic() {
198 }
199 }