be.tarsos.dsp.filters

Class IIRFilter

java.lang.Object

be.tarsos.dsp.filters.IIRFilter

All Implemented Interfaces:

AudioProcessor

Direct Known Subclasses:

BandPass, HighPass, LowPassFS, LowPassSP

public abstract class IIRFilter
extends java.lang.Object
implements AudioProcessor

An Infinite Impulse Response, or IIR, filter is a filter that uses a set of coefficients and previous filtered values to filter a stream of audio. It is an efficient way to do digital filtering. IIRFilter is a general IIRFilter that simply applies the filter designated by the filter coefficients so that sub-classes only have to dictate what the values of those coefficients are by defining the calcCoeff() function. When filling the coefficient arrays, be aware that b[0] corresponds to b1.

Author:

Damien Di Fede, Joren Six

Constructor Summary

Constructors

Constructor and Description
IIRFilter(float freq, float sampleRate) Constructs an IIRFilter with the given cutoff frequency that will be used to filter audio recorded at sampleRate.

Method Summary

Modifier and Type	Method and Description
boolean	process(AudioEvent audioEvent) Process the audio event.
void	processingFinished() Notify the AudioProcessor that no more data is available and processing has finished.
void	setFrequency(float freq)

Methods inherited from class java.lang.Object

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

Constructor Detail

IIRFilter

public IIRFilter(float freq,
                 float sampleRate)

Constructs an IIRFilter with the given cutoff frequency that will be used to filter audio recorded at sampleRate.

Parameters:

freq - the cutoff frequency

sampleRate - the sample rate of audio to be filtered

Method Detail

setFrequency

public void setFrequency(float freq)

process

public boolean process(AudioEvent audioEvent)

Description copied from interface: AudioProcessor

Process the audio event. Do the actual signal processing on an (optionally) overlapping buffer.

Specified by:

process in interface AudioProcessor

Parameters:

audioEvent - The audio event that contains audio data.

Returns:

False if the chain needs to stop here, true otherwise. This can be used to implement e.g. a silence detector.

processingFinished

public void processingFinished()

Description copied from interface: AudioProcessor

Notify the AudioProcessor that no more data is available and processing has finished. Can be used to deallocate resources or cleanup.

Specified by:

processingFinished in interface AudioProcessor