triana.types.audio

Class AudioEffect

java.lang.Object

triana.types.audio.AudioEffect

public abstract class AudioEffect
extends java.lang.Object

AudioEffect : a base class for creating audio effect that work on chunks of data. The idea behind this class is to make it convenient for operating on a chunk by chunk basis. Most algorithms operate on a continuous stream of samples or on a specific sized amount of data where no memory is required for future use. This class provides a backwards and forward memory that you can initialise and use with your algorithm. For example a reverb or echo effect may require future memory for storing the echos or reverberations within that may be added or multiplied with the next data to be processed.

You can set the size of the previous and next memory chunks. Care must be taken that you don't go out of the bounds of the maximum forward and backward memory.

When new data arrives it is inserted into an array with the previous and forward data memory prepended and appended to it. By default the previous locations are filled with the previous data (i.e. the current data will be copied into it for the next iteration) and the forward data locations can either be added to the next data processed or multiplied to them. The default mode is to add the values to the next data set that arrives. NOTE that you must take care to set the initial values so that they don't effect the first data set i.e. If you're adding then initialse Forward values to 0 or Multiplying set them to 1.

Process the next data chunk by calling preProcess and then get access to the the data array and the starting point by calling getData() and getStart(), respectively. Call postProcess to get the new data in the appropriate dimension.

NOTE : This class currently assumes that the previous and forward memory sizes are the the same size or smaller than the current chunk of data. FUTURE extensions could involve allowing extended lengths of the previous and forward memory sizes. I think that this covers most applications however except things like Large Hall Reverb which can produce an effect that may span several future data sets.

Field Summary

Fields

Modifier and Type	Field and Description
static int	ADD An identifier for adding the forward memory locations to the next data received by an AudioEffect.
static int	DO_NOTHING An identifier for ignoring the forward memory locations when receiving future inputs.
static int	MULTIPLY An identifier for multiplying the forward memory locations to the next data received by an AudioEffect.

Constructor Summary

Constructors

Constructor and Description
AudioEffect(int backwardMemSize, int forwardMemSize) Creates an audio effect with a particular backward and forward memory size.

Method Summary

Methods

Modifier and Type	Method and Description
double[]	getData() Gets data array
int	getStart() Gets the starting position of the current memory chunk with the previous and forward memory prepended and appended to it
void	initialiseForward(double val) Initializes the forward memory values to the value specified.
void	initialiseForward(double[] vals) Initializes the forward values to the values specified.
void	initialisePrevious(double val) Initializes the previous memory values to the value specified.
void	initialisePrevious(double[] vals) Initializes the previous memory values to the values specified.
void	postProcess(double[] data) This function copies the current data to the forward memory for use next time and inserts the processed values back into the given array.
void	preProcess(double[] data) This function inserts the given data into an array which comprises of the previous data, the given data and the forward data respectively.
void	setForwardMathOperation(int mode) An function setting the behaviour of how AudioEffect applies the forward memory locations to the next data received by an AudioEffect.

Methods inherited from class java.lang.Object

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

Field Detail

ADD

public static final int ADD

An identifier for adding the forward memory locations to the next data received by an AudioEffect. Use setForwardMathOperation to set the forward math mode.

See Also:

setForwardMathOperation(int), Constant Field Values

MULTIPLY

public static final int MULTIPLY

An identifier for multiplying the forward memory locations to the next data received by an AudioEffect. Use setForwardMathOperation to set the forward math mode.

See Also:

setForwardMathOperation(int), Constant Field Values

DO_NOTHING

public static final int DO_NOTHING

An identifier for ignoring the forward memory locations when receiving future inputs. Use setForwardMathOperation to set the forward math mode.

See Also:

setForwardMathOperation(int), Constant Field Values

Constructor Detail

AudioEffect

public AudioEffect(int backwardMemSize,
           int forwardMemSize)

Creates an audio effect with a particular backward and forward memory size. Enter 0 for no memory in either direction.

Method Detail

initialisePrevious

public void initialisePrevious(double val)

Initializes the previous memory values to the value specified.

initialisePrevious

public void initialisePrevious(double[] vals)
                        throws IncompatibleSizeException

Initializes the previous memory values to the values specified. The array given must be the same size as the size of the previous memory array otherwise the memory will not be initialized and an exception will be thrown

Throws:

IncompatibleSizeException

initialiseForward

public void initialiseForward(double val)

Initializes the forward memory values to the value specified.

initialiseForward

public void initialiseForward(double[] vals)
                       throws IncompatibleSizeException

Initializes the forward values to the values specified. The array given must be the same size as the size of the previous memory array otherwise the memory will not be initialized and an exception will be thrown

Throws:

IncompatibleSizeException

setForwardMathOperation

public void setForwardMathOperation(int mode)

An function setting the behaviour of how AudioEffect applies the forward memory locations to the next data received by an AudioEffect. The default mode is ADD i.e. add them to the next data chunk but other can be specified e.g. MULTIPLY and DO_NOTHING

getStart

public int getStart()

Gets the starting position of the current memory chunk with the previous and forward memory prepended and appended to it

getData

public double[] getData()

Gets data array

preProcess

public void preProcess(double[] data)

This function inserts the given data into an array which comprises of the previous data, the given data and the forward data respectively. To get a reference to the data use getData() and to get the starting point of the current data use getStart().

postProcess

public void postProcess(double[] data)
                 throws IncompatibleSizeException

This function copies the current data to the forward memory for use next time and inserts the processed values back into the given array. The given array can be set to null and then the data is copied back into the ORGINAL array supplied. Otherwise, you can provide a non null array and the data is copied into this. The given array must be the same size as the one supplied to preProcess.

Throws:

IncompatibleSizeException