| javax.sound.sampled.DataLine
| DataLine | | public interface DataLine extends Line(Code) | | DataLine adds media-related functionality to its
superinterface,
Line . This functionality includes
transport-control methods that start, stop, drain, and flush
the audio data that passes through the line. A data line can also
report the current position, volume, and audio format of the media.
Data lines are used for output of audio by means of the
subinterfaces
SourceDataLine or
Clip , which allow an application program to write data. Similarly,
audio input is handled by the subinterface
TargetDataLine ,
which allows data to be read.
A data line has an internal buffer in which
the incoming or outgoing audio data is queued. The
DataLine.drain() method blocks until this internal buffer
becomes empty, usually because all queued data has been processed. The
DataLine.flush() method discards any available queued data
from the internal buffer.
A data line produces
LineEvent.Type.START START and
LineEvent.Type.STOP STOP events whenever
it begins or ceases active presentation or capture of data. These events
can be generated in response to specific requests, or as a result of
less direct state changes. For example, if
DataLine.start() is called
on an inactive data line, and data is available for capture or playback, a
START event will be generated shortly, when data playback
or capture actually begins. Or, if the flow of data to an active data
line is constricted so that a gap occurs in the presentation of data,
a STOP event is generated.
Mixers often support synchronized control of multiple data lines.
Synchronization can be established through the Mixer interface's
Mixer.synchronize synchronize method.
See the description of the
Mixer Mixer interface
for a more complete description.
author:
Kara Kytle
version:
1.40, 07/05/05
See Also: LineEvent
since:
1.3 |
| Inner Class :public static class Info extends Line.Info | |
| Method Summary | |
| public int | available()
Obtains the number of bytes of data currently available to the
application for processing in the data line's internal buffer. | | public void | drain()
Drains queued data from the line by continuing data I/O until the
data line's internal buffer has been emptied.
This method blocks until the draining is complete. | | public void | flush()
Flushes queued data from the line. | | public int | getBufferSize()
Obtains the maximum number of bytes of data that will fit in the data line's
internal buffer. | | public AudioFormat | getFormat()
Obtains the current format (encoding, sample rate, number of channels,
etc.) of the data line's audio data.
If the line is not open and has never been opened, it returns
the default format. | | public int | getFramePosition()
Obtains the current position in the audio data, in sample frames.
The frame position measures the number of sample
frames captured by, or rendered from, the line since it was opened.
This return value will wrap around after 2^31 frames. | | public float | getLevel()
Obtains the current volume level for the line. | | public long | getLongFramePosition()
Obtains the current position in the audio data, in sample frames. | | public long | getMicrosecondPosition()
Obtains the current position in the audio data, in microseconds.
The microsecond position measures the time corresponding to the number
of sample frames captured by, or rendered from, the line since it was opened.
The level of precision is not guaranteed. | | public boolean | isActive()
Indicates whether the line is engaging in active I/O (such as playback
or capture). | | public boolean | isRunning()
Indicates whether the line is running. | | public void | start()
Allows a line to engage in data I/O. | | public void | stop()
Stops the line. |
| available | | public int available()(Code) | | Obtains the number of bytes of data currently available to the
application for processing in the data line's internal buffer. For a
source data line, this is the amount of data that can be written to the
buffer without blocking. For a target data line, this is the amount of data
available to be read by the application. For a clip, this value is always
0 because the audio data is loaded into the buffer when the clip is opened,
and persists without modification until the clip is closed.
Note that the units used are bytes, but will always
correspond to an integral number of sample frames of audio data.
An application is guaranteed that a read or
write operation of up to the number of bytes returned from
available() will not block; however, there is no guarantee
that attempts to read or write more data will block.
the amount of data available, in bytes |
| drain | | public void drain()(Code) | | Drains queued data from the line by continuing data I/O until the
data line's internal buffer has been emptied.
This method blocks until the draining is complete. Because this is a
blocking method, it should be used with care. If drain()
is invoked on a stopped line that has data in its queue, the method will
block until the line is running and the data queue becomes empty. If
drain() is invoked by one thread, and another continues to
fill the data queue, the operation will not complete.
This method always returns when the data line is closed.
See Also: DataLine.flush() |
| flush | | public void flush()(Code) | | Flushes queued data from the line. The flushed data is discarded.
In some cases, not all queued data can be discarded. For example, a
mixer can flush data from the buffer for a specific input line, but any
unplayed data already in the output buffer (the result of the mix) will
still be played. You can invoke this method after pausing a line (the
normal case) if you want to skip the "stale" data when you restart
playback or capture. (It is legal to flush a line that is not stopped,
but doing so on an active line is likely to cause a discontinuity in the
data, resulting in a perceptible click.)
See Also: DataLine.stop()
See Also: DataLine.drain() |
| getBufferSize | | public int getBufferSize()(Code) | | Obtains the maximum number of bytes of data that will fit in the data line's
internal buffer. For a source data line, this is the size of the buffer to
which data can be written. For a target data line, it is the size of
the buffer from which data can be read. Note that
the units used are bytes, but will always correspond to an integral
number of sample frames of audio data.
the size of the buffer in bytes |
| getFormat | | public AudioFormat getFormat()(Code) | | Obtains the current format (encoding, sample rate, number of channels,
etc.) of the data line's audio data.
If the line is not open and has never been opened, it returns
the default format. The default format is an implementation
specific audio format, or, if the DataLine.Info
object, which was used to retrieve this DataLine,
specifies at least one fully qualified audio format, the
last one will be used as the default format. Opening the
line with a specific audio format (e.g.
SourceDataLine.open(AudioFormat) ) will override the
default format.
current audio data format
See Also: AudioFormat |
| getFramePosition | | public int getFramePosition()(Code) | | Obtains the current position in the audio data, in sample frames.
The frame position measures the number of sample
frames captured by, or rendered from, the line since it was opened.
This return value will wrap around after 2^31 frames. It is recommended
to use getLongFramePosition instead.
the number of frames already processed since the line was opened
See Also: DataLine.getLongFramePosition() |
| getLevel | | public float getLevel()(Code) | | Obtains the current volume level for the line. This level is a measure
of the signal's current amplitude, and should not be confused with the
current setting of a gain control. The range is from 0.0 (silence) to
1.0 (maximum possible amplitude for the sound waveform). The units
measure linear amplitude, not decibels.
the current amplitude of the signal in this line, orAudioSystem.NOT_SPECIFIED |
| getLongFramePosition | | public long getLongFramePosition()(Code) | | Obtains the current position in the audio data, in sample frames.
The frame position measures the number of sample
frames captured by, or rendered from, the line since it was opened.
the number of frames already processed since the line was opened
since:
1.5 |
| getMicrosecondPosition | | public long getMicrosecondPosition()(Code) | | Obtains the current position in the audio data, in microseconds.
The microsecond position measures the time corresponding to the number
of sample frames captured by, or rendered from, the line since it was opened.
The level of precision is not guaranteed. For example, an implementation
might calculate the microsecond position from the current frame position
and the audio sample frame rate. The precision in microseconds would
then be limited to the number of microseconds per sample frame.
the number of microseconds of data processed since the line was opened |
| isRunning | | public boolean isRunning()(Code) | | Indicates whether the line is running. The default is false.
An open line begins running when the first data is presented in response to an
invocation of the start method, and continues
until presentation ceases in response to a call to stop or
because playback completes.
true if the line is running, otherwise false
See Also: DataLine.start()
See Also: DataLine.stop() |
| start | | public void start()(Code) | | Allows a line to engage in data I/O. If invoked on a line
that is already running, this method does nothing. Unless the data in
the buffer has been flushed, the line resumes I/O starting
with the first frame that was unprocessed at the time the line was
stopped. When audio capture or playback starts, a
LineEvent.Type.START START event is generated.
See Also: DataLine.stop()
See Also: DataLine.isRunning()
See Also: LineEvent |
| stop | | public void stop()(Code) | | Stops the line. A stopped line should cease I/O activity.
If the line is open and running, however, it should retain the resources required
to resume activity. A stopped line should retain any audio data in its buffer
instead of discarding it, so that upon resumption the I/O can continue where it left off,
if possible. (This doesn't guarantee that there will never be discontinuities beyond the
current buffer, of course; if the stopped condition continues
for too long, input or output samples might be dropped.) If desired, the retained data can be
discarded by invoking the flush method.
When audio capture or playback stops, a
LineEvent.Type.STOP STOP event is generated.
See Also: DataLine.start()
See Also: DataLine.isRunning()
See Also: DataLine.flush()
See Also: LineEvent |
|
|