com.tagtraum.jipes.math

Class Filters

java.lang.Object

com.tagtraum.jipes.math.Filters

public final class Filters
extends Object

Offers methods to create a number of useful filters, including MIDI filterbanks. Furthermore, you can create your own filters using the Filters.IIRFilter and Filters.FIRFilter classes.

Filters are StatefulMapFunctions and as such can be used in Mapping to be part of a SignalPipeline. To filter an AudioBuffer create a Mapping like this:

new Mapping<AudioBuffer>(AudioBufferFunctions.createMapFunction(Filters.createFir1_16thOrderLowpassCutoff(4)))

Author:

Hendrik Schreiber

See Also:

Downsample, MultirateFilters

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Filters.FIRFilter FIR (finite impulse response) filter.
static class	Filters.FourthOrderIIRFilter (Faster) implementation of a fourth order IIR (infinite impulse response) filter.
static class	Filters.IIRFilter IIR (infinite impulse response) filter.

Method Summary

Modifier and Type	Method and Description
static Filters.FourthOrderIIRFilter	createButterworth4thOrderLowpass(int factor) Fourth order Butterworth lowpass filter that lets factor-th-Nyquist pass (ω=1/factor).
static Filters.FourthOrderIIRFilter	createButterworth4thOrderLowpassCutoffEighth() Deprecated. use createButterworth4thOrderLowpass(int)
static Filters.FourthOrderIIRFilter	createButterworth4thOrderLowpassCutoffHalf() Deprecated. use createButterworth4thOrderLowpass(int)
static Filters.FourthOrderIIRFilter	createButterworth4thOrderLowpassCutoffQuarter() Deprecated. use createButterworth4thOrderLowpass(int)
static Filters.IIRFilter	createElliptic8thOrderLowpass(int factor) Eigth order Elliptic lowpass filter that lets factor-th-Nyquist pass (ω=1/factor).
static Filters.IIRFilter	createElliptic8thOrderLowpassCutoffEighth() Deprecated. use createElliptic8thOrderLowpass(int)
static Filters.IIRFilter	createElliptic8thOrderLowpassCutoffHalf() Deprecated. use createElliptic8thOrderLowpass(int)
static Filters.IIRFilter	createElliptic8thOrderLowpassCutoffQuarter() Deprecated. use createElliptic8thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpass(int factor) 16th order Fir1 (Matlab/Octave) lowpass filter that lets factor-th-Nyquist pass (ω=1/factor).
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoff160th() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoffEighth() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoffFifth() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoffHalf() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoffQuarter() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoffSeventh() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.FIRFilter	createFir1_16thOrderLowpassCutoffThird() Deprecated. use createFir1_16thOrderLowpass(int)
static Filters.IIRFilter[]	createMidiFilterBank(float sampleRate, int minMidiPitch, int maxMidiPitch) Creates a new MIDI-pitch filterbank, based on 8th order elliptic filters with 1dB passband ripple, 50dB rejection in the stopband and a Q-factor of 25.

Methods inherited from class java.lang.Object

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

Method Detail

createFir1_16thOrderLowpass

public static Filters.FIRFilter createFir1_16thOrderLowpass(int factor)
                                                     throws IllegalArgumentException

16th order Fir1 (Matlab/Octave) lowpass filter that lets factor-th-Nyquist pass (ω=1/factor). Supported factors are 1, 2, 3, 4, 5, 7, 8 and 160.

Parameters:

factor - factor

Returns:

filter

Throws:

IllegalArgumentException - if the factor is not supported.

createFir1_16thOrderLowpassCutoff160th

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoff160th()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets 160th-Nyquist pass (ω=1/160).

Returns:

filter

createFir1_16thOrderLowpassCutoffSeventh

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoffSeventh()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets seventh-Nyquist pass (ω=1/7).

Returns:

filter

createFir1_16thOrderLowpassCutoffFifth

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoffFifth()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets fifth-Nyquist pass (ω=1/5).

Returns:

filter

createFir1_16thOrderLowpassCutoffThird

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoffThird()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets third-Nyquist pass (ω=1/3).

Returns:

filter

createFir1_16thOrderLowpassCutoffHalf

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoffHalf()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets half-Nyquist pass (ω=0.5).

Returns:

filter

createFir1_16thOrderLowpassCutoffQuarter

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoffQuarter()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets quarter-Nyquist pass (ω=0.25).

Returns:

filter

createFir1_16thOrderLowpassCutoffEighth

public static Filters.FIRFilter createFir1_16thOrderLowpassCutoffEighth()

Deprecated. use createFir1_16thOrderLowpass(int)

16th order Fir1 (Matlab) lowpass filter that lets eighth-Nyquist pass (ω=0.125).

Returns:

filter

createButterworth4thOrderLowpass

public static Filters.FourthOrderIIRFilter createButterworth4thOrderLowpass(int factor)
                                                                     throws IllegalArgumentException

Fourth order Butterworth lowpass filter that lets factor-th-Nyquist pass (ω=1/factor). Supported factors are 2, 4, and 8.

Parameters:

factor - factor

Returns:

filter

Throws:

IllegalArgumentException - if the factor is not supported.

createButterworth4thOrderLowpassCutoffHalf

public static Filters.FourthOrderIIRFilter createButterworth4thOrderLowpassCutoffHalf()

Deprecated. use createButterworth4thOrderLowpass(int)

Fourth order Butterworth lowpass filter that lets half-Nyquist pass (ω=0.5).

Returns:

filter

createButterworth4thOrderLowpassCutoffQuarter

public static Filters.FourthOrderIIRFilter createButterworth4thOrderLowpassCutoffQuarter()

Deprecated. use createButterworth4thOrderLowpass(int)

Fourth order Butterworth lowpass filter that lets quarter-Nyquist pass (ω=0.25).

Returns:

filter

createButterworth4thOrderLowpassCutoffEighth

public static Filters.FourthOrderIIRFilter createButterworth4thOrderLowpassCutoffEighth()

Deprecated. use createButterworth4thOrderLowpass(int)

Fourth order Butterworth lowpass filter that lets eighth-Nyquist pass (ω=0.125).

Returns:

filter

createElliptic8thOrderLowpass

public static Filters.IIRFilter createElliptic8thOrderLowpass(int factor)
                                                       throws IllegalArgumentException

Eigth order Elliptic lowpass filter that lets factor-th-Nyquist pass (ω=1/factor). Supported factors are 2, 4, and 8.

Parameters:

factor - factor

Returns:

filter

Throws:

IllegalArgumentException - if the factor is not supported.

createElliptic8thOrderLowpassCutoffHalf

public static Filters.IIRFilter createElliptic8thOrderLowpassCutoffHalf()

Deprecated. use createElliptic8thOrderLowpass(int)

Eigth order Elliptic lowpass filter that lets half-Nyquist pass (ω=0.5).
Created with Matlab/Octave: format long e; ellip(8,1,50,0.5)

Returns:

filter

createElliptic8thOrderLowpassCutoffQuarter

public static Filters.IIRFilter createElliptic8thOrderLowpassCutoffQuarter()

Deprecated. use createElliptic8thOrderLowpass(int)

Eigth order Elliptic lowpass filter that lets quarter-Nyquist pass (ω=0.25).
Created with Matlab/Octave: format long e; ellip(8,1,50,0.25)

Returns:

filter

createElliptic8thOrderLowpassCutoffEighth

public static Filters.IIRFilter createElliptic8thOrderLowpassCutoffEighth()

Deprecated. use createElliptic8thOrderLowpass(int)

Eigth order Elliptic lowpass filter that lets eighth-Nyquist pass (ω=0.125).
Created with Matlab/Octave: format long e; ellip(8,1,50,0.125)

Returns:

filter

createMidiFilterBank

public static Filters.IIRFilter[] createMidiFilterBank(float sampleRate,
                                                       int minMidiPitch,
                                                       int maxMidiPitch)
                                                throws IllegalArgumentException

Creates a new MIDI-pitch filterbank, based on 8th order elliptic filters with 1dB passband ripple, 50dB rejection in the stopband and a Q-factor of 25. Unless the sampling rate does not allow it, all pitches 0-127 are present.

If only a subset of the complete filterbank is desired, you can specify a minimum and a maximum pitch (both incl.).

Note that the individual filters are stateful and can't simply ce re-used in a different context.

Parameters:

sampleRate - one of several supported sample rates (currently 44100Hz, 22050Hz, 11025Hz, 5512.5Hz, 2756.25Hz, 4410Hz, 882Hz)

minMidiPitch - smallest pitch to include (inclusive)

maxMidiPitch - greatest pitch to include (inclusive)

Returns:

array of filters for the desired pitch range

Throws:

IllegalArgumentException - if the desired sample rate is not supported

See Also:

createMidi44100HzElliptic8thOrderFilterBank(int, int)