comirva.audio.extraction
Class FluctuationPatternCentExtractor

java.lang.Object
  comirva.audio.extraction.AttributeExtractor
      comirva.audio.extraction.AudioFeatureExtractor
          comirva.audio.extraction.FluctuationPatternCentExtractor

public class FluctuationPatternCentExtractor
extends AudioFeatureExtractor

Title: Fluctuation Patterns

Description:

This class supports the extraction of the so-called "Fluctuation Patterns" from an audio stream. This is a advanced version based on the cent scale instead of the bark scale.

See Also:

AudioFeatureExtractor, FluctuationPattern

Constructor Summary

FluctuationPatternCentExtractor()
The default constructor uses segments of size 65536 samples.

FluctuationPatternCentExtractor(int fftSize, int segmentSize)
Constructs an individualized FluctuationPatternExtractor.

Method Summary

Attribute	calculate(java.lang.Object input) This method is used to calculate the fluctuation pattern for a whole song.
AttributeExtractor	copy() This method returns a copy of an AttributeExtractor.
int	getAttributeType() Returns the type of the attribute that the class implementing this interface will return as the result of its extraction process.
double[]	getFluxWeights() Returns weights for the amplitude modulation coefficients based on the psychoarcoustic model of the fluctuation strength.
static double	getMedian(double[] array) Computes the median of all the elements in the array.
java.lang.String	toString() Returns the feature extractors name.

Methods inherited from class java.lang.Object

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

Constructor Detail

FluctuationPatternCentExtractor

public FluctuationPatternCentExtractor()

The default constructor uses segments of size 65536 samples. This corresponds to about 6 sec. of audio @11kHz.

FluctuationPatternCentExtractor

public FluctuationPatternCentExtractor(int fftSize,
                                       int segmentSize)

Constructs an individualized FluctuationPatternExtractor. The number of samples to use for a segment has to be chosen with respect to an 11kHz audio stream. An fft size of 512 is used to get the rhythmic structure out of the sone representation. This corresponds to a range of 10bpm up to 2584bpm.

Parameters:

fftSize - int number of cent values to consider

segmentSize - int number of samples a segments consists of

Method Detail

copy

public AttributeExtractor copy()

Description copied from class: AttributeExtractor

This method returns a copy of an AttributeExtractor. This is useful to use multiple extractors in parallel or distributed environments as AttributeExtractors can be stateful.

Specified by:

copy in class AttributeExtractor

Returns:

calculate

public Attribute calculate(java.lang.Object input)
                    throws java.lang.IllegalArgumentException,
                           java.io.IOException

This method is used to calculate the fluctuation pattern for a whole song. The song must be handed to this method as an AudioPreProcessor object. All settings are set by the constructor, so this method can easily be called for a large number of songs to extract this feature.

Specified by:

calculate in class AttributeExtractor

Parameters:

input - Object an AudioPreProcessor representing the audio input stream;

Returns:

Feature a FluctuationPattern feature is returned as a result of this feature extraction process

Throws:

java.io.IOException - if there are any problems regarding the inputstream

java.lang.IllegalArgumentException - raised if method contract of a subroutine is violated

getFluxWeights

public double[] getFluxWeights()

Returns weights for the amplitude modulation coefficients based on the psychoarcoustic model of the fluctuation strength. The number of the weights depends on the base frequency. For details take a look at [1].

Returns:

double[] weights for the amplitude modulation coefficients

getMedian

public static double getMedian(double[] array)
                        throws java.lang.IllegalArgumentException

Computes the median of all the elements in the array. The elements in the array are sorted after a calling this method.

Parameters:

array - double[] array of values; must not be a null value and must contain at least one element;

Returns:

double the median of all the elements of the given array

Throws:

java.lang.IllegalArgumentException - raised if method contract is violated

getAttributeType

public int getAttributeType()

Returns the type of the attribute that the class implementing this interface will return as the result of its extraction process. By definition this is the hash code of the attribute's class name.

Specified by:

getAttributeType in class AttributeExtractor

Returns:

int an integer uniquely identifying the returned Attribute

toString

public java.lang.String toString()

Returns the feature extractors name.

Overrides:

toString in class java.lang.Object

Returns:

String name of this feature extractor