/*
* @(#)TargetDataLine.java 1.20 03/12/19
*
* Copyright 2004 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 1.20 03/12/19
* @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();
}
|
