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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
* {@link Mixer#getLine getLine} method of {@code Mixer} with an appropriate
* {@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
* {@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
* {@link LineEvent.Type#STOP STOP} event is generated. A
* {@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
* {@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 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
*/
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 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
*/
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 {@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 {@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:
* <p style="text-align:center">
* {@code [ bytes written ] % [frame size in bytes ] == 0}
* <p>
* 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 off the offset from the beginning of the array, in bytes
* @param len the length, in bytes, of the valid data in the array (in
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