toxi.audio
Class IIRFilter

java.lang.Object
  toxi.audio.IIRFilter

public class IIRFilter
extends java.lang.Object

This class provides a simple IIR filter implementation with one of lowpass, highpass or bandpass characteristics. The class can filter individual samples or entire signal buffers. The filter function always has this form:

 y = 1 / a0 * (b0 * x0 + b1 * x1 + b2 * x2 - a1 * q1 - a2 * q2)
 

http://en.wikipedia.org/wiki/Infinite_impulse_response

Nested Class Summary

static class

IIRFilter.Type

Constructor Summary

IIRFilter(IIRFilter.Type type, float sampleRate)

Method Summary

float	calculateAmplitude(float[] in) Just calculates the amplitude of the filtered signal, but doesn't actually apply the filter.
IIRFilter	clear()
float	filter(float in) Applies filter to a single sample value.
float	filter(float[] in) Destructively filters a the given signal buffer.
float	getDecay()
IIRFilter	init(float freq, float q) Initializes the filter to the given cutoff frequency and Q (resonance) settings.
IIRFilter	setDecay(float decay)

Methods inherited from class java.lang.Object

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

Constructor Detail

IIRFilter

public IIRFilter(IIRFilter.Type type,
                 float sampleRate)

Parameters:

type -

sampleRate -

Method Detail

calculateAmplitude

public float calculateAmplitude(float[] in)

Just calculates the amplitude of the filtered signal, but doesn't actually apply the filter.

Parameters:

in -

Returns:

amplitude

clear

public IIRFilter clear()

filter

public float filter(float in)

Applies filter to a single sample value.

Parameters:

in -

Returns:

filtered sample

filter

public float filter(float[] in)

Destructively filters a the given signal buffer. The original samples are overwritten.

Parameters:

in -

Returns:

amplitude of filtered signal

getDecay

public float getDecay()

Returns:

the decay

init

public IIRFilter init(float freq,
                      float q)

Initializes the filter to the given cutoff frequency and Q (resonance) settings. This function needs to be called at least once before the filter can be used.

Parameters:

freq -

q -

Returns:

itself

setDecay

public IIRFilter setDecay(float decay)

Parameters:

decay - the decay to set

Returns:

itself