The SourceDataLine.java Java example source code
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package javax.sound.sampled;
/**
* A source data line is a data line to which data may be written. It acts as
* a source to its mixer. An application writes audio bytes to a source data line,
* which handles the buffering of the bytes and delivers them to the mixer.
* The mixer may mix the samples with those from other sources and then deliver
* the mix to a target such as an output port (which may represent an audio output
* device on a sound card).
* <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 source data line may act as a target for audio data.
* <p>
* A source data line can be obtained from a mixer by invoking the
* <code>{@link Mixer#getLine getLine} method of Mixer with
* an appropriate <code>{@link DataLine.Info} object.
* <p>
* The <code>SourceDataLine interface provides a method for writing
* audio data to the data line's buffer. Applications that play or mix
* audio should write data to the source data line quickly enough to keep the
* buffer from underflowing (emptying), which could cause discontinuities in
* the audio that are perceived as clicks. Applications can use the
* <code>{@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. The amount of data which can be written
* to the buffer without blocking is the difference between the buffer size
* and the amount of queued data. If the delivery of audio output
* stops due to underflow, a <code>{@link LineEvent.Type#STOP STOP} event is
* generated. A <code>{@link LineEvent.Type#START START} event is generated
* when the audio output resumes.
*
* @author Kara Kytle
* @see Mixer
* @see DataLine
* @see TargetDataLine
* @since 1.3
*/
public interface SourceDataLine extends DataLine {
/**
* Opens the line with the specified format and suggested 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}.
* <p>
* If this operation succeeds, the line is marked as open, and an
* <code>{@link LineEvent.Type#OPEN OPEN} event is dispatched to the
* line's listeners.
* <p>
* Invoking this method on a line which is already open is illegal
* and may result in an <code>IllegalStateException.
* <p>
* Note that 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
* @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
*/
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}.
* <p>
* If this operation succeeds, the line is marked as open, and an
* <code>{@link LineEvent.Type#OPEN OPEN} event is dispatched to the
* line's listeners.
* <p>
* Invoking this method on a line which is already open is illegal
* and may result in an <code>IllegalStateException.
* <p>
* Note that 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
*/
public void open(AudioFormat format) throws LineUnavailableException;
/**
* Writes audio data to the mixer via this source data line. The requested
* number of bytes of data are read from the specified array,
* starting at the given offset into the array, and written to the data
* line's buffer. If the caller attempts to write more data than can
* currently be written (see <code>{@link DataLine#available available}),
* this method blocks until the requested amount of data has been written.
* This applies even if the requested amount of data to write is greater
* than the data line's buffer size. However, if the data line is closed,
* stopped, or flushed before the requested amount has been written,
* the method no longer blocks, but returns the number of bytes
* written thus far.
* <p>
* The number of bytes that can be written without blocking can be ascertained
* using the <code>{@link DataLine#available available} method of the
* <code>DataLine interface. (While it is guaranteed that
* this number of bytes can be written without blocking, there is no guarantee
* that attempts to write additional data will block.)
* <p>
* The number of bytes to write must represent an integral number of
* sample frames, such that:
* <br>
* <center>[ bytes written ] % [frame size in bytes ] == 0
* <br>
* The return value will always meet this requirement. A request to write a
* number of bytes representing a non-integral number of sample frames cannot
* be fulfilled and may result in an <code>IllegalArgumentException.
*
* @param b a byte array containing data to be written to the data line
* @param len the length, in bytes, of the valid data in the array
* (in other words, the requested amount of data to write, in bytes)
* @param off the offset from the beginning of the array, in bytes
* @return the number of bytes actually written
* @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 TargetDataLine#read
* @see DataLine#available
*/
public int write(byte[] b, int off, int len);
/**
* Obtains the number of sample frames of audio data that can be written to
* the mixer, via this data line, without blocking. Note that the return
* value measures sample frames, not bytes.
* @return the number of sample frames currently available for writing
* @see TargetDataLine#availableRead
*/
//public int availableWrite();
}
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