Java tutorial
/* * Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.sound.sampled; /** * A target data line is a type of {@link DataLine} 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 * {@link Mixer#getLine getLine} method of {@code Mixer} with an appropriate * {@link DataLine.Info} object. * <p> * The {@code TargetDataLine} 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 * {@link DataLine#available available} method defined in the {@code DataLine} * 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 * @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 * {@code 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 {@link DataLine#getBufferSize} * <p> * If this operation succeeds, the line is marked as open, and an * {@link LineEvent.Type#OPEN OPEN} 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}. * <p> * Some lines, once closed, cannot be reopened. Attempts to reopen such a * line will always result in a {@code LineUnavailableException}. * * @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} 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 */ 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 * {@link DataLine#getBufferSize} * <p> * If this operation succeeds, the line is marked as open, and an * {@link LineEvent.Type#OPEN OPEN} 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}. * <p> * Some lines, once closed, cannot be reopened. Attempts to reopen such a * line will always result in a {@code LineUnavailableException}. * * @param format the desired audio format * @throws LineUnavailableException if the line cannot be opened due to * resource restrictions * @throws IllegalArgumentException if {@code format} 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 */ 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 {@link DataLine#available available} method of the * {@code DataLine} 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: * <p style="text-align:center"> * {@code [ bytes read ] % [frame size in bytes ] == 0} * <p> * 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} is negative * @throws ArrayIndexOutOfBoundsException if {@code off} is negative, or * {@code off+len} is greater than the length of the array {@code b} * * @see SourceDataLine#write * @see DataLine#available */ 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(); }