1 /*
2 * Copyright (c) 2002-2021, City of Paris
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright notice
10 * and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright notice
13 * and the following disclaimer in the documentation and/or other materials
14 * provided with the distribution.
15 *
16 * 3. Neither the name of 'Mairie de Paris' nor 'Lutece' nor the names of its
17 * contributors may be used to endorse or promote products derived from
18 * this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 *
32 * License 1.0
33 */
34 package fr.paris.lutece.plugins.captcha.modules.jcaptcha.service.sound.filter;
35
36 import javax.sound.sampled.AudioFormat;
37 import javax.sound.sampled.AudioInputStream;
38
39 /**
40 * A abstract class designed to filter sound samples. Since SoundFilters may use internal buffering of samples, a new SoundFilter object should be created for
41 * every sound played. However, SoundFilters can be reused after they are finished by called the reset() method.
42 * <p>
43 *
44 * @see FilteredSoundStream
45 */
46 public abstract class SoundFilter
47 {
48 protected static final int SAMPLE_SIZE_16_BIT = 16;
49 protected static final int SAMPLE_SIZE_8_BIT = 8;
50
51 /**
52 * Resets this SoundFilter. Does nothing by default.
53 */
54 public void reset( )
55 {
56 // do nothing
57 }
58
59 /**
60 * Gets the remaining size, in bytes, that this filter plays after the sound is finished. An example would be an echo that plays longer than it's original
61 * sound. This method returns 0 by default.
62 *
63 * @return remaining size
64 */
65 public int getRemainingSize( )
66 {
67 return 0;
68 }
69
70 /**
71 * Filters an array of samples. Samples should be in 16-bit, signed, little-endian format. This method should be implemented by subclasses.
72 *
73 * @param samples
74 * the samples
75 * @param offset
76 * the offset
77 * @param length
78 * the length
79 * @param sampleSizeInBits
80 * the sample size in bits
81 */
82 public abstract void filter( byte [ ] samples, int offset, int length, int sampleSizeInBits );
83
84 /**
85 * Convenience method for getting a 8-bit sample from a byte array. Samples should be in 8-bit, unsigned, little-endian format.
86 *
87 * @param buffer
88 * the buffer
89 * @param position
90 * the position
91 * @return 8 bit sample
92 */
93 public static short get8bitSample( byte [ ] buffer, int position )
94 {
95 return (short) ( buffer [position] & 0xff );
96 }
97
98 /**
99 * Convenience method for setting a 8-bit sample in a byte array. Samples should be in 8-bit, unsigned, little-endian format.
100 *
101 * @param buffer
102 * the buffer
103 * @param position
104 * the position
105 * @param sample
106 * the sample
107 *
108 */
109 public static void set8bitSample( byte [ ] buffer, int position, short sample )
110 {
111 buffer [position] = (byte) ( sample & 0xff );
112 }
113
114 /**
115 * Convenience method for getting a 16-bit sample from a byte array. Samples should be in 16-bit, signed, little-endian format.
116 *
117 * @param buffer
118 * the buffer
119 * @param position
120 * the position
121 *
122 * @return 16 bit sample
123 *
124 */
125 public static short get16bitSample( byte [ ] buffer, int position )
126 {
127 return (short) ( ( ( buffer [position + 1] & 0xff ) << 8 ) | ( buffer [position] & 0xff ) );
128 }
129
130 /**
131 * Convenience method for setting a 16-bit sample in a byte array. Samples should be in 16-bit, signed, little-endian format.
132 *
133 * @param buffer
134 * the buffer
135 * @param position
136 * the position
137 * @param sample
138 * the sample
139 *
140 */
141 public static void set16bitSample( byte [ ] buffer, int position, short sample )
142 {
143 buffer [position] = (byte) ( sample & 0xff );
144 buffer [position + 1] = (byte) ( ( sample >> 8 ) & 0xff );
145 }
146
147 /**
148 * Return the audio format corresponding to the input stream Overrided by the filters that mofify AudioFormat
149 *
150 * @param audioInputStream
151 * the audio input stream
152 * @return the audio format corresponding to the input stream
153 */
154 public AudioFormat getAudioFormat( AudioInputStream audioInputStream )
155 {
156 return audioInputStream.getFormat( );
157 }
158 }