be.tarsos.dsp.mfcc

Class MFCC

java.lang.Object

be.tarsos.dsp.mfcc.MFCC

All Implemented Interfaces:

AudioProcessor

public class MFCC
extends java.lang.Object
implements AudioProcessor

Constructor Summary

Constructors

Constructor and Description
MFCC(int samplesPerFrame, float sampleRate, int amountOfCepstrumCoef, int amountOfMelFilters, float lowerFilterFreq, float upperFilterFreq)
MFCC(int samplesPerFrame, int sampleRate)

Method Summary

Modifier and Type	Method and Description
void	calculateFilterBanks() calculates the FFT bin indices calls: none called by: featureExtraction
float[]	cepCoefficients(float[] f) Cepstral coefficients are calculated from the output of the Non-linear Transformation method calls: none called by: featureExtraction
int[]	getCenterFrequencies()
float[]	getMFCC()
float[]	magnitudeSpectrum(float[] frame) computes the magnitude spectrum of the input frame calls: none called by: featureExtraction
float[]	melFilter(float[] bin, int[] centerFrequencies) Calculate the output of the mel filter calls: none called by: featureExtraction
float[]	nonLinearTransformation(float[] fbank) the output of mel filtering is subjected to a logarithm function (natural logarithm) calls: none called by: featureExtraction
boolean	process(AudioEvent audioEvent) Process the audio event.
void	processingFinished() Notify the AudioProcessor that no more data is available and processing has finished.

Methods inherited from class java.lang.Object

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

Constructor Detail

MFCC

public MFCC(int samplesPerFrame,
            int sampleRate)

MFCC

public MFCC(int samplesPerFrame,
            float sampleRate,
            int amountOfCepstrumCoef,
            int amountOfMelFilters,
            float lowerFilterFreq,
            float upperFilterFreq)

Method Detail

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

magnitudeSpectrum

public float[] magnitudeSpectrum(float[] frame)

computes the magnitude spectrum of the input frame
calls: none
called by: featureExtraction

Parameters:

frame - Input frame signal

Returns:

Magnitude Spectrum array

calculateFilterBanks

public final void calculateFilterBanks()

calculates the FFT bin indices
calls: none
called by: featureExtraction

nonLinearTransformation

public float[] nonLinearTransformation(float[] fbank)

the output of mel filtering is subjected to a logarithm function (natural logarithm)
calls: none
called by: featureExtraction

Parameters:

fbank - Output of mel filtering

Returns:

Natural log of the output of mel filtering

melFilter

public float[] melFilter(float[] bin,
                         int[] centerFrequencies)

Calculate the output of the mel filter
calls: none called by: featureExtraction

Parameters:

bin - The bins.

centerFrequencies - The frequency centers.

Returns:

Output of mel filter.

cepCoefficients

public float[] cepCoefficients(float[] f)

Cepstral coefficients are calculated from the output of the Non-linear Transformation method
calls: none
called by: featureExtraction

Parameters:

f - Output of the Non-linear Transformation method

Returns:

Cepstral Coefficients

getMFCC

public float[] getMFCC()

getCenterFrequencies

public int[] getCenterFrequencies()