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/* * @(#)TargetDataLine.java 1.21 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.sound.sampled; /** * A target data line is a type of <code>{@link DataLine}</code> from which * audio data can be read. The most common example is a data line that gets * its data from an audio capture device. (The device is implemented as a * mixer that writes to the target data line.) * <p> * Note that the naming convention for this interface reflects the relationship * between the line and its mixer. From the perspective of an application, * a target data line may act as a source for audio data. * <p> * The target data line can be obtained from a mixer by invoking the * <code>{@link Mixer#getLine getLine}</code> * method of <code>Mixer</code> with an appropriate * <code>{@link DataLine.Info}</code> object. * <p> * The <code>TargetDataLine</code> interface provides a method for reading the * captured data from the target data line's buffer.Applications * that record audio should read data from the target data line quickly enough * to keep the buffer from overflowing, which could cause discontinuities in * the captured data that are perceived as clicks. Applications can use the * <code>{@link DataLine#available available}</code> method defined in the * <code>DataLine</code> interface to determine the amount of data currently * queued in the data line's buffer. If the buffer does overflow, * the oldest queued data is discarded and replaced by new data. * * @author Kara Kytle * @version 1.21 05/11/17 * @see Mixer * @see DataLine * @see SourceDataLine * @since 1.3 */ public interface TargetDataLine extends DataLine { /** * Opens the line with the specified format and requested buffer size, * causing the line to acquire any required system resources and become * operational. * <p> * The buffer size is specified in bytes, but must represent an integral * number of sample frames. Invoking this method with a requested buffer * size that does not meet this requirement may result in an * IllegalArgumentException. The actual buffer size for the open line may * differ from the requested buffer size. The value actually set may be * queried by subsequently calling <code>{@link DataLine#getBufferSize}</code> * <p> * If this operation succeeds, the line is marked as open, and an * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the * line's listeners. * <p> * Invoking this method on a line that is already open is illegal * and may result in an <code>IllegalStateException</code>. * <p> * Some lines, once closed, cannot be reopened. Attempts * to reopen such a line will always result in a * <code>LineUnavailableException</code>. * * @param format the desired audio format * @param bufferSize the desired buffer size, in bytes. * @throws LineUnavailableException if the line cannot be * opened due to resource restrictions * @throws IllegalArgumentException if the buffer size does not represent * an integral number of sample frames, * or if <code>format</code> is not fully specified or invalid * @throws IllegalStateException if the line is already open * @throws SecurityException if the line cannot be * opened due to security restrictions * * @see #open(AudioFormat) * @see Line#open * @see Line#close * @see Line#isOpen * @see LineEvent */ public void open(AudioFormat format, int bufferSize) throws LineUnavailableException; /** * Opens the line with the specified format, causing the line to acquire any * required system resources and become operational. * * <p> * The implementation chooses a buffer size, which is measured in bytes but * which encompasses an integral number of sample frames. The buffer size * that the system has chosen may be queried by subsequently calling <code>{@link DataLine#getBufferSize}</code> * <p> * If this operation succeeds, the line is marked as open, and an * <code>{@link LineEvent.Type#OPEN OPEN}</code> event is dispatched to the * line's listeners. * <p> * Invoking this method on a line that is already open is illegal * and may result in an <code>IllegalStateException</code>. * <p> * Some lines, once closed, cannot be reopened. Attempts * to reopen such a line will always result in a * <code>LineUnavailableException</code>. * * @param format the desired audio format * @throws LineUnavailableException if the line cannot be * opened due to resource restrictions * @throws IllegalArgumentException if <code>format</code> * is not fully specified or invalid * @throws IllegalStateException if the line is already open * @throws SecurityException if the line cannot be * opened due to security restrictions * * @see #open(AudioFormat, int) * @see Line#open * @see Line#close * @see Line#isOpen * @see LineEvent */ public void open(AudioFormat format) throws LineUnavailableException; /** * Reads audio data from the data line's input buffer. The requested * number of bytes is read into the specified array, starting at * the specified offset into the array in bytes. This method blocks until * the requested amount of data has been read. However, if the data line * is closed, stopped, drained, or flushed before the requested amount has * been read, the method no longer blocks, but returns the number of bytes * read thus far. * <p> * The number of bytes that can be read without blocking can be ascertained * using the <code>{@link DataLine#available available}</code> method of the * <code>DataLine</code> interface. (While it is guaranteed that * this number of bytes can be read without blocking, there is no guarantee * that attempts to read additional data will block.) * <p> * The number of bytes to be read must represent an integral number of * sample frames, such that: * <br> * <center><code>[ bytes read ] % [frame size in bytes ] == 0</code></center> * <br> * The return value will always meet this requirement. A request to read a * number of bytes representing a non-integral number of sample frames cannot * be fulfilled and may result in an IllegalArgumentException. * * @param b a byte array that will contain the requested input data when * this method returns * @param off the offset from the beginning of the array, in bytes * @param len the requested number of bytes to read * @return the number of bytes actually read * @throws IllegalArgumentException if the requested number of bytes does * not represent an integral number of sample frames. * or if <code>len</code> is negative. * @throws ArrayIndexOutOfBoundsException if <code>off</code> is negative, * or <code>off+len</code> is greater than the length of the array * <code>b</code>. * * @see SourceDataLine#write * @see DataLine#available */ public int read(byte[] b, int off, int len); /** * Obtains the number of sample frames of audio data that can be read from * the target data line without blocking. Note that the return value * measures sample frames, not bytes. * @return the number of sample frames currently available for reading * @see SourceDataLine#availableWrite */ //public int availableRead(); }