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