TargetDataLine


1   /*
2    * @(#)TargetDataLine.java  1.20 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package javax.sound.sampled;    
9   
10  /**
11   * A target data line is a type of <code>{@link DataLine}</code> from which 
12   * audio data can be read.  The most common example is a data line that gets
13   * its data from an audio capture device.  (The device is implemented as a
14   * mixer that writes to the target data line.)
15   * <p>
16   * Note that the naming convention for this interface reflects the relationship
17   * between the line and its mixer.  From the perspective of an application,
18   * a target data line may act as a source for audio data.
19   * <p>
20   * The target data line can be obtained from a mixer by invoking the 
21   * <code>{@link Mixer#getLine getLine}</code> 
22   * method of <code>Mixer</code> with an appropriate 
23   * <code>{@link DataLine.Info}</code> object.
24   * <p>
25   * The <code>TargetDataLine</code> interface provides a method for reading the
26   * captured data from the target data line's buffer.Applications 
27   * that record audio should read data from the target data line quickly enough 
28   * to keep the buffer from overflowing, which could cause discontinuities in 
29   * the captured data that are perceived as clicks.  Applications can use the 
30   * <code>{@link DataLine#available available}</code> method defined in the
31   * <code>DataLine</code> interface to determine the amount of data currently
32   * queued in the data line's buffer.  If the buffer does overflow,
33   * the oldest queued data is discarded and replaced by new data.
34   * 
35   * @author Kara Kytle
36   * @version 1.20 03/12/19
37   * @see Mixer
38   * @see DataLine
39   * @see SourceDataLine
40   * @since 1.3
41   */
42  public interface TargetDataLine extends DataLine   {
43  
44  
45      /**
46       * Opens the line with the specified format and requested buffer size,
47       * causing the line to acquire any required system resources and become 
48       * operational.  
49       * <p>
50       * The buffer size is specified in bytes, but must represent an integral 
51       * number of sample frames.  Invoking this method with a requested buffer 
52       * size that does not meet this requirement may result in an 
53       * IllegalArgumentException.  The actual buffer size for the open line may 
54       * differ from the requested buffer size.  The value actually set may be 
55       * queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>  
56       * <p>
57       * If this operation succeeds, the line is marked as open, and an 
58       * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the 
59       * line's listeners.
60       * <p>
61       * Invoking this method on a line that is already open is illegal
62       * and may result in an <code>IllegalStateException</code>.
63       * <p>
64       * Some lines, once closed, cannot be reopened.  Attempts
65       * to reopen such a line will always result in a 
66       * <code>LineUnavailableException</code>.
67       *
68       * @param format the desired audio format
69       * @param bufferSize the desired buffer size, in bytes.
70       * @throws LineUnavailableException if the line cannot be
71       * opened due to resource restrictions
72       * @throws IllegalArgumentException if the buffer size does not represent
73       * an integral number of sample frames,
74       * or if <code>format</code> is not fully specified or invalid
75       * @throws IllegalStateException if the line is already open
76       * @throws SecurityException if the line cannot be
77       * opened due to security restrictions
78       *
79       * @see #open(AudioFormat)
80       * @see Line#open
81       * @see Line#close
82       * @see Line#isOpen
83       * @see LineEvent
84       */
85      public void open(AudioFormat   format, int bufferSize) throws LineUnavailableException  ;
86  
87  
88      /**
89       * Opens the line with the specified format, causing the line to acquire any 
90       * required system resources and become operational.  
91       *   
92       * <p>
93       * The implementation chooses a buffer size, which is measured in bytes but 
94       * which encompasses an integral number of sample frames.  The buffer size 
95       * that the system has chosen may be queried by subsequently calling <code>{@link DataLine#getBufferSize}</code>  
96       * <p>
97       * If this operation succeeds, the line is marked as open, and an 
98       * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the 
99       * line's listeners.
100      * <p>
101      * Invoking this method on a line that is already open is illegal
102      * and may result in an <code>IllegalStateException</code>.
103      * <p>
104      * Some lines, once closed, cannot be reopened.  Attempts
105      * to reopen such a line will always result in a 
106      * <code>LineUnavailableException</code>.
107      *
108      * @param format the desired audio format
109      * @throws LineUnavailableException if the line cannot be
110      * opened due to resource restrictions
111      * @throws IllegalArgumentException if <code>format</code>
112      * is not fully specified or invalid
113      * @throws IllegalStateException if the line is already open
114      * @throws SecurityException if the line cannot be
115      * opened due to security restrictions
116      *
117      * @see #open(AudioFormat, int)
118      * @see Line#open
119      * @see Line#close
120      * @see Line#isOpen
121      * @see LineEvent
122      */
123     public void open(AudioFormat   format) throws LineUnavailableException  ;
124 
125 
126     /**
127      * Reads audio data from the data line's input buffer.   The requested 
128      * number of bytes is read into the specified array, starting at
129      * the specified offset into the array in bytes.  This method blocks until
130      * the requested amount of data has been read.  However, if the data line 
131      * is closed, stopped, drained, or flushed before the requested amount has 
132      * been read, the method no longer blocks, but returns the number of bytes
133      * read thus far. 
134      * <p>
135      * The number of bytes that can be read without blocking can be ascertained
136      * using the <code>{@link DataLine#available available}</code> method of the
137      * <code>DataLine</code> interface.  (While it is guaranteed that
138      * this number of bytes can be read without blocking, there is no guarantee
139      * that attempts to read additional data will block.)
140      * <p>
141      * The number of bytes to be read must represent an integral number of
142      * sample frames, such that:
143      * <br>
144      * <center><code>[ bytes read ] % [frame size in bytes ] == 0</code></center>
145      * <br>
146      * The return value will always meet this requirement.  A request to read a 
147      * number of bytes representing a non-integral number of sample frames cannot 
148      * be fulfilled and may result in an IllegalArgumentException.
149      *
150      * @param b a byte array that will contain the requested input data when 
151      * this method returns
152      * @param off the offset from the beginning of the array, in bytes
153      * @param len the requested number of bytes to read
154      * @return the number of bytes actually read
155      * @throws IllegalArgumentException if the requested number of bytes does
156      * not represent an integral number of sample frames.
157      * or if <code>len</code> is negative.
158      * @throws ArrayIndexOutOfBoundsException if <code>off</code> is negative,
159      * or <code>off+len</code> is greater than the length of the array
160      * <code>b</code>. 
161      *
162      * @see SourceDataLine#write
163      * @see DataLine#available
164      */ 
165     public int read(byte[] b, int off, int len);
166 
167     /**
168      * Obtains the number of sample frames of audio data that can be read from 
169      * the target data line without blocking.  Note that the return value 
170      * measures sample frames, not bytes.
171      * @return the number of sample frames currently available for reading
172      * @see SourceDataLine#availableWrite
173      */
174     //public int availableRead();
175 }       
176
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags