1 /*
2 * Copyright 1999-2003 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.sound.sampled;
27
28 /**
29 * A target data line is a type of <code>{@link DataLine}</code> from which
30 * audio data can be read. The most common example is a data line that gets
31 * its data from an audio capture device. (The device is implemented as a
32 * mixer that writes to the target data line.)
33 * <p>
34 * Note that the naming convention for this interface reflects the relationship
35 * between the line and its mixer. From the perspective of an application,
36 * a target data line may act as a source for audio data.
37 * <p>
38 * The target data line can be obtained from a mixer by invoking the
39 * <code>{@link Mixer#getLine getLine}</code>
40 * method of <code>Mixer</code> with an appropriate
41 * <code>{@link DataLine.Info}</code> object.
42 * <p>
43 * The <code>TargetDataLine</code> interface provides a method for reading the
44 * captured data from the target data line's buffer.Applications
45 * that record audio should read data from the target data line quickly enough
46 * to keep the buffer from overflowing, which could cause discontinuities in
47 * the captured data that are perceived as clicks. Applications can use the
48 * <code>{@link DataLine#available available}</code> method defined in the
49 * <code>DataLine</code> interface to determine the amount of data currently
50 * queued in the data line's buffer. If the buffer does overflow,
51 * the oldest queued data is discarded and replaced by new data.
52 *
53 * @author Kara Kytle
54 * @see Mixer
55 * @see DataLine
56 * @see SourceDataLine
57 * @since 1.3
58 */
59 public interface TargetDataLine extends DataLine {
60
61
62 /**
63 * Opens the line with the specified format and requested buffer size,
64 * causing the line to acquire any required system resources and become
65 * operational.
66 * <p>
67 * The buffer size is specified in bytes, but must represent an integral
68 * number of sample frames. Invoking this method with a requested buffer
69 * size that does not meet this requirement may result in an
70 * IllegalArgumentException. The actual buffer size for the open line may
71 * differ from the requested buffer size. The value actually set may be
72 * queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>
73 * <p>
74 * If this operation succeeds, the line is marked as open, and an
75 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the
76 * line's listeners.
77 * <p>
78 * Invoking this method on a line that is already open is illegal
79 * and may result in an <code>IllegalStateException</code>.
80 * <p>
81 * Some lines, once closed, cannot be reopened. Attempts
82 * to reopen such a line will always result in a
83 * <code>LineUnavailableException</code>.
84 *
85 * @param format the desired audio format
86 * @param bufferSize the desired buffer size, in bytes.
87 * @throws LineUnavailableException if the line cannot be
88 * opened due to resource restrictions
89 * @throws IllegalArgumentException if the buffer size does not represent
90 * an integral number of sample frames,
91 * or if <code>format</code> is not fully specified or invalid
92 * @throws IllegalStateException if the line is already open
93 * @throws SecurityException if the line cannot be
94 * opened due to security restrictions
95 *
96 * @see #open(AudioFormat)
97 * @see Line#open
98 * @see Line#close
99 * @see Line#isOpen
100 * @see LineEvent
101 */
102 public void open(AudioFormat format, int bufferSize) throws LineUnavailableException;
103
104
105 /**
106 * Opens the line with the specified format, causing the line to acquire any
107 * required system resources and become operational.
108 *
109 * <p>
110 * The implementation chooses a buffer size, which is measured in bytes but
111 * which encompasses an integral number of sample frames. The buffer size
112 * that the system has chosen may be queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>
113 * <p>
114 * If this operation succeeds, the line is marked as open, and an
115 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the
116 * line's listeners.
117 * <p>
118 * Invoking this method on a line that is already open is illegal
119 * and may result in an <code>IllegalStateException</code>.
120 * <p>
121 * Some lines, once closed, cannot be reopened. Attempts
122 * to reopen such a line will always result in a
123 * <code>LineUnavailableException</code>.
124 *
125 * @param format the desired audio format
126 * @throws LineUnavailableException if the line cannot be
127 * opened due to resource restrictions
128 * @throws IllegalArgumentException if <code>format</code>
129 * is not fully specified or invalid
130 * @throws IllegalStateException if the line is already open
131 * @throws SecurityException if the line cannot be
132 * opened due to security restrictions
133 *
134 * @see #open(AudioFormat, int)
135 * @see Line#open
136 * @see Line#close
137 * @see Line#isOpen
138 * @see LineEvent
139 */
140 public void open(AudioFormat format) throws LineUnavailableException;
141
142
143 /**
144 * Reads audio data from the data line's input buffer. The requested
145 * number of bytes is read into the specified array, starting at
146 * the specified offset into the array in bytes. This method blocks until
147 * the requested amount of data has been read. However, if the data line
148 * is closed, stopped, drained, or flushed before the requested amount has
149 * been read, the method no longer blocks, but returns the number of bytes
150 * read thus far.
151 * <p>
152 * The number of bytes that can be read without blocking can be ascertained
153 * using the <code>{@link DataLine#available available}</code> method of the
154 * <code>DataLine</code> interface. (While it is guaranteed that
155 * this number of bytes can be read without blocking, there is no guarantee
156 * that attempts to read additional data will block.)
157 * <p>
158 * The number of bytes to be read must represent an integral number of
159 * sample frames, such that:
160 * <br>
161 * <center><code>[ bytes read ] % [frame size in bytes ] == 0</code></center>
162 * <br>
163 * The return value will always meet this requirement. A request to read a
164 * number of bytes representing a non-integral number of sample frames cannot
165 * be fulfilled and may result in an IllegalArgumentException.
166 *
167 * @param b a byte array that will contain the requested input data when
168 * this method returns
169 * @param off the offset from the beginning of the array, in bytes
170 * @param len the requested number of bytes to read
171 * @return the number of bytes actually read
172 * @throws IllegalArgumentException if the requested number of bytes does
173 * not represent an integral number of sample frames.
174 * or if <code>len</code> is negative.
175 * @throws ArrayIndexOutOfBoundsException if <code>off</code> is negative,
176 * or <code>off+len</code> is greater than the length of the array
177 * <code>b</code>.
178 *
179 * @see SourceDataLine#write
180 * @see DataLine#available
181 */
182 public int read(byte[] b, int off, int len);
183
184 /**
185 * Obtains the number of sample frames of audio data that can be read from
186 * the target data line without blocking. Note that the return value
187 * measures sample frames, not bytes.
188 * @return the number of sample frames currently available for reading
189 * @see SourceDataLine#availableWrite
190 */
191 //public int availableRead();
192 }
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