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 source data line is a data line to which data may be written. It acts as
030 * a source to its mixer. An application writes audio bytes to a source data line,
031 * which handles the buffering of the bytes and delivers them to the mixer.
032 * The mixer may mix the samples with those from other sources and then deliver
033 * the mix to a target such as an output port (which may represent an audio output
034 * device on a sound card).
035 * <p>
036 * Note that the naming convention for this interface reflects the relationship
037 * between the line and its mixer. From the perspective of an application,
038 * a source data line may act as a target for audio data.
039 * <p>
040 * A source data line can be obtained from a mixer by invoking the
041 * <code>{@link Mixer#getLine getLine}</code> method of <code>Mixer</code> with
042 * an appropriate <code>{@link DataLine.Info}</code> object.
043 * <p>
044 * The <code>SourceDataLine</code> interface provides a method for writing
045 * audio data to the data line's buffer. Applications that play or mix
046 * audio should write data to the source data line quickly enough to keep the
047 * buffer from underflowing (emptying), which could cause discontinuities in
048 * the audio that are perceived as clicks. Applications can use the
049 * <code>{@link DataLine#available available}</code> method defined in the
050 * <code>DataLine</code> interface to determine the amount of data currently
051 * queued in the data line's buffer. The amount of data which can be written
052 * to the buffer without blocking is the difference between the buffer size
053 * and the amount of queued data. If the delivery of audio output
054 * stops due to underflow, a <code>{@link LineEvent.Type#STOP STOP}</code> event is
055 * generated. A <code>{@link LineEvent.Type#START START}</code> event is generated
056 * when the audio output resumes.
057 *
058 * @author Kara Kytle
059 * @version 1.27 07/05/05
060 * @see Mixer
061 * @see DataLine
062 * @see TargetDataLine
063 * @since 1.3
064 */
065 public interface SourceDataLine extends DataLine {
066
067 /**
068 * Opens the line with the specified format and suggested buffer size,
069 * causing the line to acquire any required
070 * system resources and become operational.
071 * <p>
072 * The buffer size is specified in bytes, but must represent an integral
073 * number of sample frames. Invoking this method with a requested buffer
074 * size that does not meet this requirement may result in an
075 * IllegalArgumentException. The actual buffer size for the open line may
076 * differ from the requested buffer size. The value actually set may be
077 * queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>.
078 * <p>
079 * If this operation succeeds, the line is marked as open, and an
080 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the
081 * line's listeners.
082 * <p>
083 * Invoking this method on a line which is already open is illegal
084 * and may result in an <code>IllegalStateException</code>.
085 * <p>
086 * Note that some lines, once closed, cannot be reopened. Attempts
087 * to reopen such a line will always result in a
088 * <code>LineUnavailableException</code>.
089 *
090 * @param format the desired audio format
091 * @param bufferSize the desired buffer size
092 * @throws LineUnavailableException if the line cannot be
093 * opened due to resource restrictions
094 * @throws IllegalArgumentException if the buffer size does not represent
095 * an integral number of sample frames,
096 * or if <code>format</code> is not fully specified or invalid
097 * @throws IllegalStateException if the line is already open
098 * @throws SecurityException if the line cannot be
099 * opened due to security restrictions
100 *
101 * @see #open(AudioFormat)
102 * @see Line#open
103 * @see Line#close
104 * @see Line#isOpen
105 * @see LineEvent
106 */
107 public void open(AudioFormat format, int bufferSize)
108 throws LineUnavailableException;
109
110 /**
111 * Opens the line with the specified format, causing the line to acquire any
112 * required system resources and become operational.
113 *
114 * <p>
115 * The implementation chooses a buffer size, which is measured in bytes but
116 * which encompasses an integral number of sample frames. The buffer size
117 * that the system has chosen may be queried by subsequently calling
118 * <code>{@link DataLine#getBufferSize}</code>.
119 * <p>
120 * If this operation succeeds, the line is marked as open, and an
121 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the
122 * line's listeners.
123 * <p>
124 * Invoking this method on a line which is already open is illegal
125 * and may result in an <code>IllegalStateException</code>.
126 * <p>
127 * Note that some lines, once closed, cannot be reopened. Attempts
128 * to reopen such a line will always result in a
129 * <code>LineUnavailableException</code>.
130 *
131 * @param format the desired audio format
132 * @throws LineUnavailableException if the line cannot be
133 * opened due to resource restrictions
134 * @throws IllegalArgumentException if <code>format</code>
135 * is not fully specified or invalid
136 * @throws IllegalStateException if the line is already open
137 * @throws SecurityException if the line cannot be
138 * opened due to security restrictions
139 *
140 * @see #open(AudioFormat, int)
141 * @see Line#open
142 * @see Line#close
143 * @see Line#isOpen
144 * @see LineEvent
145 */
146 public void open(AudioFormat format)
147 throws LineUnavailableException;
148
149 /**
150 * Writes audio data to the mixer via this source data line. The requested
151 * number of bytes of data are read from the specified array,
152 * starting at the given offset into the array, and written to the data
153 * line's buffer. If the caller attempts to write more data than can
154 * currently be written (see <code>{@link DataLine#available available}</code>),
155 * this method blocks until the requested amount of data has been written.
156 * This applies even if the requested amount of data to write is greater
157 * than the data line's buffer size. However, if the data line is closed,
158 * stopped, or flushed before the requested amount has been written,
159 * the method no longer blocks, but returns the number of bytes
160 * written thus far.
161 * <p>
162 * The number of bytes that can be written without blocking can be ascertained
163 * using the <code>{@link DataLine#available available}</code> method of the
164 * <code>DataLine</code> interface. (While it is guaranteed that
165 * this number of bytes can be written without blocking, there is no guarantee
166 * that attempts to write additional data will block.)
167 * <p>
168 * The number of bytes to write must represent an integral number of
169 * sample frames, such that:
170 * <br>
171 * <center><code>[ bytes written ] % [frame size in bytes ] == 0</code></center>
172 * <br>
173 * The return value will always meet this requirement. A request to write a
174 * number of bytes representing a non-integral number of sample frames cannot
175 * be fulfilled and may result in an <code>IllegalArgumentException</code>.
176 *
177 * @param b a byte array containing data to be written to the data line
178 * @param len the length, in bytes, of the valid data in the array
179 * (in other words, the requested amount of data to write, in bytes)
180 * @param off the offset from the beginning of the array, in bytes
181 * @return the number of bytes actually written
182 * @throws IllegalArgumentException if the requested number of bytes does
183 * not represent an integral number of sample frames,
184 * or if <code>len</code> is negative
185 * @throws ArrayIndexOutOfBoundsException if <code>off</code> is negative,
186 * or <code>off+len</code> is greater than the length of the array
187 * <code>b</code>.
188 *
189 * @see TargetDataLine#read
190 * @see DataLine#available
191 */
192 public int write(byte[] b, int off, int len);
193
194 /**
195 * Obtains the number of sample frames of audio data that can be written to
196 * the mixer, via this data line, without blocking. Note that the return
197 * value measures sample frames, not bytes.
198 * @return the number of sample frames currently available for writing
199 * @see TargetDataLine#availableRead
200 */
201 //public int availableWrite();
202 }
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