1 /*
2 * Copyright (c) 1999, 2017, 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
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7 * published by the Free Software Foundation. Oracle designates this
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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 *
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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 * <p style="text-align:center">
163 * {@code [ bytes written ] % [frame size in bytes ] == 0}
164 * <p>
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 }