* 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. *
* 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. *
* 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. *
* 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}. *
* 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. *
* Invoking this method on a line which is already open is illegal and may * result in an {@code IllegalStateException}. *
* 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. *
* 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}. *
* 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. *
* Invoking this method on a line which is already open is illegal and may * result in an {@code IllegalStateException}. *
* 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. *
* 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.) *
* The number of bytes to write must represent an integral number of sample * frames, such that: *
* {@code [ bytes written ] % [frame size in bytes ] == 0} *
* 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 */ 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(); }