001 /*
002 * Copyright 1999-2003 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package javax.sound.sampled;
027
028 /**
029 * A target data line is a type of <code>{@link DataLine}</code> from which
030 * audio data can be read. The most common example is a data line that gets
031 * its data from an audio capture device. (The device is implemented as a
032 * mixer that writes to the target data line.)
033 * <p>
034 * Note that the naming convention for this interface reflects the relationship
035 * between the line and its mixer. From the perspective of an application,
036 * a target data line may act as a source for audio data.
037 * <p>
038 * The target data line can be obtained from a mixer by invoking the
039 * <code>{@link Mixer#getLine getLine}</code>
040 * method of <code>Mixer</code> with an appropriate
041 * <code>{@link DataLine.Info}</code> object.
042 * <p>
043 * The <code>TargetDataLine</code> interface provides a method for reading the
044 * captured data from the target data line's buffer.Applications
045 * that record audio should read data from the target data line quickly enough
046 * to keep the buffer from overflowing, which could cause discontinuities in
047 * the captured data that are perceived as clicks. Applications can use the
048 * <code>{@link DataLine#available available}</code> method defined in the
049 * <code>DataLine</code> interface to determine the amount of data currently
050 * queued in the data line's buffer. If the buffer does overflow,
051 * the oldest queued data is discarded and replaced by new data.
052 *
053 * @author Kara Kytle
054 * @version 1.27 07/05/05
055 * @see Mixer
056 * @see DataLine
057 * @see SourceDataLine
058 * @since 1.3
059 */
060 public interface TargetDataLine extends DataLine {
061
062 /**
063 * Opens the line with the specified format and requested buffer size,
064 * causing the line to acquire any required system resources and become
065 * operational.
066 * <p>
067 * The buffer size is specified in bytes, but must represent an integral
068 * number of sample frames. Invoking this method with a requested buffer
069 * size that does not meet this requirement may result in an
070 * IllegalArgumentException. The actual buffer size for the open line may
071 * differ from the requested buffer size. The value actually set may be
072 * queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>
073 * <p>
074 * If this operation succeeds, the line is marked as open, and an
075 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the
076 * line's listeners.
077 * <p>
078 * Invoking this method on a line that is already open is illegal
079 * and may result in an <code>IllegalStateException</code>.
080 * <p>
081 * Some lines, once closed, cannot be reopened. Attempts
082 * to reopen such a line will always result in a
083 * <code>LineUnavailableException</code>.
084 *
085 * @param format the desired audio format
086 * @param bufferSize the desired buffer size, in bytes.
087 * @throws LineUnavailableException if the line cannot be
088 * opened due to resource restrictions
089 * @throws IllegalArgumentException if the buffer size does not represent
090 * an integral number of sample frames,
091 * or if <code>format</code> is not fully specified or invalid
092 * @throws IllegalStateException if the line is already open
093 * @throws SecurityException if the line cannot be
094 * opened due to security restrictions
095 *
096 * @see #open(AudioFormat)
097 * @see Line#open
098 * @see Line#close
099 * @see Line#isOpen
100 * @see LineEvent
101 */
102 public void open(AudioFormat format, int bufferSize)
103 throws LineUnavailableException;
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)
141 throws LineUnavailableException;
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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