jm.audio

Class RTMixer

java.lang.Object

jm.audio.RTMixer

All Implemented Interfaces:

AudioChainListener

public class RTMixer
extends java.lang.Object
implements AudioChainListener

RTMixer is responsible for convolving the audio signals being pulled from n number of RTLines. RTMixer uses a single JMF Java Sound SourceDataLine object for writing the newly convolved signal to the audio device. Buffers of audio sample data are passed to the SourceDataLine at a rate set by the Control Rate value. The contol rate sets the size of the audio buffers used by RTMixer, SourceDataLine and Instrument. Information about sample rate and channels is retrieved from the first audio object of the first instrument of the first RTLine. Therefore, there is an assumption that all instruments have the same sample rate and number of channels.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	channels The number of channels to be used when setting up SourceDataLine
protected double	controlRate The control rate is used to set how often in instrument returns a full buffer of audio samples.
long	currentTime A Timer which keeps track of how many samples have been written since this object started
protected int	sampleRate The sampleRate to be used when establishing the JMF SourceDataLine

Constructor Summary

Constructors

Constructor and Description
RTMixer(RTLine[] rtlines) The RTMixer constructor sets a number of attributes and opens a JMF java sound sourceDataLine.
RTMixer(RTLine[] rtlines, double controlRate) The RTMixer constructor sets a number of attributes and opens a JMF java sound sourceDataLine.

Method Summary

Methods

Modifier and Type	Method and Description
void	actionLines(java.lang.Object obj, int actionNumber) This method passes on external action requests (i.e.
void	addLines(RTLine[] lines)
void	begin() Begin starts RTMixer.
void	controlChange(float[] buffer, int returned, boolean finished) The controlChange method is called every time an instrument fills a sample buffer.
void	finalize()
void	pause() Pauses RTMixer playback.
void	stop() Stops RTMixer playback.
void	unPause() Continues the RTMixer playback.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

sampleRate

protected int sampleRate

The sampleRate to be used when establishing the JMF SourceDataLine

channels

protected int channels

The number of channels to be used when setting up SourceDataLine

currentTime

public long currentTime

A Timer which keeps track of how many samples have been written since this object started

controlRate

protected double controlRate

The control rate is used to set how often in instrument returns a full buffer of audio samples. This is acheived by changing the size of the instrument buffers. It is critical to the audio performance and can be tuned to the suit the different computers. Smaller values are prefereable because they give jMusic audio less latency, but values that are too small will cause the audio system to choke and splutter.

Constructor Detail

RTMixer

public RTMixer(RTLine[] rtlines)

The RTMixer constructor sets a number of attributes and opens a JMF java sound sourceDataLine.

Parameters:

inst - the Instruments to be processed by this object.

RTMixer

public RTMixer(RTLine[] rtlines,
       double controlRate)

The RTMixer constructor sets a number of attributes and opens a JMF java sound sourceDataLine.

Parameters:

inst - - The Instruments to be processed by this object.

controlRate - - Sets the regularity of audio parameter change. The control rate is used to set how often in instrument returns a full buffer of audio samples. This is acheived by changing the size of the instrument buffers.

Control rate is critical to the audio performance and can be tuned to the suit different computers. Smaller values are prefereable because the resulting smaller buffer equates to a less latency, but values that are too small will cause the audio system to choke and splutter. Values typically fall in the rage 0.01 - 0.005.

Method Detail

addLines

public void addLines(RTLine[] lines)

controlChange

public void controlChange(float[] buffer,
                 int returned,
                 boolean finished)

The controlChange method is called every time an instrument fills a sample buffer. This method is responsible for receiving the sample buffer and convolving it with the data in sampleArray.

Specified by:

controlChange in interface AudioChainListener

Parameters:

buffer - a sample array filled by an instrument

returned - the number of samples in the buffer

finished - indicates whether the instruments current note is finished or not.

begin

public void begin()

Begin starts RTMixer.

pause

public void pause()

Pauses RTMixer playback.

unPause

public void unPause()

Continues the RTMixer playback.

stop

public void stop()

Stops RTMixer playback.

actionLines

public void actionLines(java.lang.Object obj,
               int actionNumber)

This method passes on external action requests (i.e. gui based action events) to each RTLine's externalAction method).

Parameters:

obj - an unspecified object type (externalAction will cast)

actionNumber - an indentifyer for the originator of the action request (i.e. if there are three buttons there would actionNumbers 1,2 and 3)

finalize

public void finalize()

Overrides:

finalize in class java.lang.Object