1 /* 2 * Copyright (c) 1999, 2003, 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 javax.sound.sampled; 27 28 29 /** 30 * A source data line is a data line to which data may be written. It acts as 31 * a source to its mixer. An application writes audio bytes to a source data line, 32 * which handles the buffering of the bytes and delivers them to the mixer. 33 * The mixer may mix the samples with those from other sources and then deliver 34 * the mix to a target such as an output port (which may represent an audio output 35 * device on a sound card). 36 * <p> 37 * Note that the naming convention for this interface reflects the relationship 38 * between the line and its mixer. From the perspective of an application, 39 * a source data line may act as a target for audio data. 40 * <p> 41 * A source data line can be obtained from a mixer by invoking the 42 * <code>{@link Mixer#getLine getLine}</code> method of <code>Mixer</code> with 43 * an appropriate <code>{@link DataLine.Info}</code> object. 44 * <p> 45 * The <code>SourceDataLine</code> interface provides a method for writing 46 * audio data to the data line's buffer. Applications that play or mix 47 * audio should write data to the source data line quickly enough to keep the 48 * buffer from underflowing (emptying), which could cause discontinuities in 49 * the audio that are perceived as clicks. Applications can use the 50 * <code>{@link DataLine#available available}</code> method defined in the 51 * <code>DataLine</code> interface to determine the amount of data currently 52 * queued in the data line's buffer. The amount of data which can be written 53 * to the buffer without blocking is the difference between the buffer size 54 * and the amount of queued data. If the delivery of audio output 55 * stops due to underflow, a <code>{@link LineEvent.Type#STOP STOP}</code> event is 56 * generated. A <code>{@link LineEvent.Type#START START}</code> event is generated 57 * when the audio output resumes. 58 * 59 * @author Kara Kytle 60 * @see Mixer 61 * @see DataLine 62 * @see TargetDataLine 63 * @since 1.3 64 */ 65 public interface SourceDataLine extends DataLine { 66 67 68 /** 69 * Opens the line with the specified format and suggested buffer size, 70 * causing the line to acquire any required 71 * system resources and become operational. 72 * <p> 73 * The buffer size is specified in bytes, but must represent an integral 74 * number of sample frames. Invoking this method with a requested buffer 75 * size that does not meet this requirement may result in an 76 * IllegalArgumentException. The actual buffer size for the open line may 77 * differ from the requested buffer size. The value actually set may be 78 * queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>. 79 * <p> 80 * If this operation succeeds, the line is marked as open, and an 81 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the 82 * line's listeners. 83 * <p> 84 * Invoking this method on a line which is already open is illegal 85 * and may result in an <code>IllegalStateException</code>. 86 * <p> 87 * Note that some lines, once closed, cannot be reopened. Attempts 88 * to reopen such a line will always result in a 89 * <code>LineUnavailableException</code>. 90 * 91 * @param format the desired audio format 92 * @param bufferSize the desired buffer size 93 * @throws LineUnavailableException if the line cannot be 94 * opened due to resource restrictions 95 * @throws IllegalArgumentException if the buffer size does not represent 96 * an integral number of sample frames, 97 * or if <code>format</code> is not fully specified or invalid 98 * @throws IllegalStateException if the line is already open 99 * @throws SecurityException if the line cannot be 100 * opened due to security restrictions 101 * 102 * @see #open(AudioFormat) 103 * @see Line#open 104 * @see Line#close 105 * @see Line#isOpen 106 * @see LineEvent 107 */ 108 public void open(AudioFormat format, int bufferSize) throws LineUnavailableException; 109 110 111 /** 112 * Opens the line with the specified format, causing the line to acquire any 113 * required system resources and become operational. 114 * 115 * <p> 116 * The implementation chooses a buffer size, which is measured in bytes but 117 * which encompasses an integral number of sample frames. The buffer size 118 * that the system has chosen may be queried by subsequently calling 119 * <code>{@link DataLine#getBufferSize}</code>. 120 * <p> 121 * If this operation succeeds, the line is marked as open, and an 122 * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the 123 * line's listeners. 124 * <p> 125 * Invoking this method on a line which is already open is illegal 126 * and may result in an <code>IllegalStateException</code>. 127 * <p> 128 * Note that some lines, once closed, cannot be reopened. Attempts 129 * to reopen such a line will always result in a 130 * <code>LineUnavailableException</code>. 131 * 132 * @param format the desired audio format 133 * @throws LineUnavailableException if the line cannot be 134 * opened due to resource restrictions 135 * @throws IllegalArgumentException if <code>format</code> 136 * is not fully specified or invalid 137 * @throws IllegalStateException if the line is already open 138 * @throws SecurityException if the line cannot be 139 * opened due to security restrictions 140 * 141 * @see #open(AudioFormat, int) 142 * @see Line#open 143 * @see Line#close 144 * @see Line#isOpen 145 * @see LineEvent 146 */ 147 public void open(AudioFormat format) throws LineUnavailableException; 148 149 150 /** 151 * Writes audio data to the mixer via this source data line. The requested 152 * number of bytes of data are read from the specified array, 153 * starting at the given offset into the array, and written to the data 154 * line's buffer. If the caller attempts to write more data than can 155 * currently be written (see <code>{@link DataLine#available available}</code>), 156 * this method blocks until the requested amount of data has been written. 157 * This applies even if the requested amount of data to write is greater 158 * than the data line's buffer size. However, if the data line is closed, 159 * stopped, or flushed before the requested amount has been written, 160 * the method no longer blocks, but returns the number of bytes 161 * written thus far. 162 * <p> 163 * The number of bytes that can be written without blocking can be ascertained 164 * using the <code>{@link DataLine#available available}</code> method of the 165 * <code>DataLine</code> interface. (While it is guaranteed that 166 * this number of bytes can be written without blocking, there is no guarantee 167 * that attempts to write additional data will block.) 168 * <p> 169 * The number of bytes to write must represent an integral number of 170 * sample frames, such that: 171 * <br> 172 * <center><code>[ bytes written ] % [frame size in bytes ] == 0</code></center> 173 * <br> 174 * The return value will always meet this requirement. A request to write a 175 * number of bytes representing a non-integral number of sample frames cannot 176 * be fulfilled and may result in an <code>IllegalArgumentException</code>. 177 * 178 * @param b a byte array containing data to be written to the data line 179 * @param len the length, in bytes, of the valid data in the array 180 * (in other words, the requested amount of data to write, in bytes) 181 * @param off the offset from the beginning of the array, in bytes 182 * @return the number of bytes actually written 183 * @throws IllegalArgumentException if the requested number of bytes does 184 * not represent an integral number of sample frames, 185 * or if <code>len</code> is negative 186 * @throws ArrayIndexOutOfBoundsException if <code>off</code> is negative, 187 * or <code>off+len</code> is greater than the length of the array 188 * <code>b</code>. 189 * 190 * @see TargetDataLine#read 191 * @see DataLine#available 192 */ 193 public int write(byte[] b, int off, int len); 194 195 /** 196 * Obtains the number of sample frames of audio data that can be written to 197 * the mixer, via this data line, without blocking. Note that the return 198 * value measures sample frames, not bytes. 199 * @return the number of sample frames currently available for writing 200 * @see TargetDataLine#availableRead 201 */ 202 //public int availableWrite(); 203 }