The
Clip
interface represents a special kind of data line whose
audio data can be loaded prior to playback, instead of being streamed in
real time.
Because the data is pre-loaded and has a known length, you can set a clip
to start playing at any position in its audio data. You can also create a
loop, so that when the clip is played it will cycle repeatedly. Loops are
specified with a starting and ending sample frame, along with the number of
times that the loop should be played.
Clips may be obtained from a Mixer
that supports lines
of this type. Data is loaded into a clip when it is opened.
Playback of an audio clip may be started and stopped using the start
and stop
methods. These methods do not reset the media position;
start
causes playback to continue from the position where playback
was last stopped. To restart playback from the beginning of the clip's audio
data, simply follow the invocation of stop
with setFramePosition(0), which rewinds the media to the beginning
of the clip.
A value indicating that looping should continue indefinitely rather than
complete after a specific number of loops.
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.
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.
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.)
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.
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.
) will override the
default format.
Obtains the media length in sample frames.
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.
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.
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.
Obtains the media duration in microseconds
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.
Indicates whether the line is engaging in active I/O (such as playback
or capture). When an inactive line becomes active, it sends a
START
event to its listeners. Similarly, when
an active line becomes inactive, it sends a
STOP
event.
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.
Starts looping playback from the current position. Playback will
continue to the loop's end point, then loop back to the loop start point
count
times, and finally continue playback to the end of
the clip.
If the current position when this method is invoked is greater than the
loop end point, playback simply continues to the
end of the clip without looping.
A count
value of 0 indicates that any current looping should
cease and playback should continue to the end of the clip. The behavior
is undefined when this method is invoked with any other value during a
loop operation.
If playback is stopped during looping, the current loop status is
cleared; the behavior of subsequent loop and start requests is not
affected by an interrupted loop operation.
Opens the clip, meaning that it should acquire any required
system resources and become operational. The clip is opened
with the format and audio data indicated.
If this operation succeeds, the line is marked as open and an
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 IllegalStateException.
Note that some lines, once closed, cannot be reopened. Attempts
to reopen such a line will always result in a
LineUnavailableException
.
Opens the clip with the format and audio data present in the provided audio
input stream. Opening a clip means that it should acquire any required
system resources and become operational. If this operation
input stream. If this operation
succeeds, the line is marked open and an
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 IllegalStateException.
Note that some lines, once closed, cannot be reopened. Attempts
to reopen such a line will always result in a
LineUnavailableException
.
Sets the media position in sample frames. The position is zero-based;
the first frame is frame number zero. When the clip begins playing the
next time, it will start by playing the frame at this position.
To obtain the current position in sample frames, use the
getFramePosition
method of DataLine
.
Sets the first and last sample frames that will be played in
the loop. The ending point must be greater than
or equal to the starting point, and both must fall within the
the size of the loaded media. A value of 0 for the starting
point means the beginning of the loaded media. Similarly, a value of -1
for the ending point indicates the last frame of the media.
Sets the media position in microseconds. When the clip begins playing the
next time, it will start at this position.
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.
To obtain the current position in microseconds, use the
getMicrosecondPosition
method of DataLine
.
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
START
event is generated.
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
STOP
event is generated.