org.openimaj.audio.features

Class JAudioFeatureExtractor

java.lang.Object

org.openimaj.audio.Audio

org.openimaj.audio.AudioStream

org.openimaj.audio.processor.AudioProcessor

org.openimaj.audio.features.JAudioFeatureExtractor

All Implemented Interfaces:

FeatureExtractor<DoubleFV,SampleChunk>

Direct Known Subclasses:

MagnitudeSpectrum, MFCC, SpectralFlux

public abstract class JAudioFeatureExtractor
extends AudioProcessor
implements FeatureExtractor<DoubleFV,SampleChunk>

This class provides an OpenIMAJ wrapper for the JAudio library of feature extractors. It provides the marshalling of data from the OpenIMAJ audio streams into the data structures necessary for the jAudio FeatureExtractor interface.

Version:

$Author$, $Revision$, $Date$

Author:

David Dupplaw (dpd@ecs.soton.ac.uk)

Field Summary

Fields

Modifier and Type	Field and Description
protected jAudioFeatureExtractor.AudioFeatures.FeatureExtractor	featureExtractor The jaudio feature extractor

Fields inherited from class org.openimaj.audio.Audio

format

Constructor Summary

Constructors

Constructor and Description
JAudioFeatureExtractor() Default constructor for ad-hoc processing.
JAudioFeatureExtractor(AudioStream as) Chainable constructor

Method Summary

Methods

Modifier and Type	Method and Description
DoubleFV	extractFeature(SampleChunk sc) Calculates the feature for each channel, then flattens the channel arrays into a single DoubleFV.
abstract double[][]	getExtraInputs(double[] samples, double sampleRate) Returns the extra inputs required by a specific feature extractor
double[][]	getLastCalculatedFeature()
double[][]	process(double[][] samples, double sampleRate) Process the given sample data.
double[]	process(double[] samples, double sampleRate) Process the given sample array for a single channel
SampleBuffer	process(SampleBuffer sb) Process the given sample buffer.
SampleChunk	process(SampleChunk sample) Function that takes a sample chunk and processes the chunk.
void	setLastCalculatedFeature(double[][] lastCalculatedFeature)

Methods inherited from class org.openimaj.audio.processor.AudioProcessor

getLength, getUnderlyingStream, nextSampleChunk, process, processingComplete, reset, setUnderlyingStream

Methods inherited from class org.openimaj.audio.AudioStream

seek

Methods inherited from class org.openimaj.audio.Audio

getFormat, setFormat

Methods inherited from class java.lang.Object

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

Field Detail

featureExtractor

protected jAudioFeatureExtractor.AudioFeatures.FeatureExtractor featureExtractor

The jaudio feature extractor

Constructor Detail

JAudioFeatureExtractor

public JAudioFeatureExtractor()

Default constructor for ad-hoc processing.

JAudioFeatureExtractor

public JAudioFeatureExtractor(AudioStream as)

Chainable constructor

Parameters:

as - The audio stream to chain to.

Method Detail

process

public SampleBuffer process(SampleBuffer sb)

Process the given sample buffer.

Parameters:

sb - The sample buffer

Returns:

The sample buffer

process

public double[][] process(double[][] samples,
                 double sampleRate)

Process the given sample data.

Parameters:

samples - The samples

sampleRate - The sample rate of the data

Returns:

The features

process

public double[] process(double[] samples,
               double sampleRate)

Process the given sample array for a single channel

Parameters:

samples - The samples for a single channel

sampleRate - The sample rate of the data

Returns:

The feature for the single channel

getExtraInputs

public abstract double[][] getExtraInputs(double[] samples,
                        double sampleRate)

Returns the extra inputs required by a specific feature extractor

Parameters:

samples - The samples for a single channel

sampleRate - The sample rate of the data

Returns:

The extra input

process

public SampleChunk process(SampleChunk sample)
                    throws Exception

Function that takes a sample chunk and processes the chunk. It should also return a sample chunk containing the processed data. If wished, the chunk may be side-affected and the input chunk returned. It should not be assumed that the input chunk will be side-affected, but it must be noted that it is possible that it could be. This process function may also return null. If null is returned it means that the rest of the audio stream is not required to be processed by this processing function. Whether the rest of the sample chunks are copied or ignored is up to the caller.

Specified by:

process in class AudioProcessor

Parameters:

sample - The sample chunk to process.

Returns:

A sample chunk containing processed data.

Throws:

Exception - If the processing could not take place

See Also:

AudioProcessor.process(org.openimaj.audio.SampleChunk)

extractFeature

public DoubleFV extractFeature(SampleChunk sc)

Calculates the feature for each channel, then flattens the channel arrays into a single DoubleFV. Extract features from an object and return them.

Specified by:

extractFeature in interface FeatureExtractor<DoubleFV,SampleChunk>

Parameters:

sc - the object to extract from

Returns:

the extracted feature

See Also:

FeatureExtractor.extractFeature(java.lang.Object)

getLastCalculatedFeature

public double[][] getLastCalculatedFeature()

Returns:

the lastCalculatedFeature

setLastCalculatedFeature

public void setLastCalculatedFeature(double[][] lastCalculatedFeature)

Parameters:

lastCalculatedFeature - the lastCalculatedFeature to set