org.openimaj.audio.filters

Class WeightedWindowedAudioProcessor

java.lang.Object

org.openimaj.audio.Audio

org.openimaj.audio.AudioStream

org.openimaj.audio.processor.AudioProcessor

org.openimaj.audio.processor.FixedSizeSampleAudioProcessor

org.openimaj.audio.filters.WeightedWindowedAudioProcessor

All Implemented Interfaces:

Iterable<SampleChunk>

Direct Known Subclasses:

HanningAudioProcessor

public abstract class WeightedWindowedAudioProcessor
extends FixedSizeSampleAudioProcessor

Applies a weighted window on top of the audio signal. Assumes that all incoming audio samples will be the same size (or smaller) than the initial sample. This is because the weights function is cached the first time that the function is called.

Just one method needs to be overridden in the implementing class and that is the method that generates the window of weights to be applied to the signal. The weighting is then applied automatically. The method will only be called once and lazily.

Author:

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

Created:

31 Oct 2011

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	useWeights Whether to apply the weights to the incoming signal
protected double[]	weightTable A table of weights

Fields inherited from class org.openimaj.audio.Audio

format

Constructor Summary

Constructors

Constructor and Description
WeightedWindowedAudioProcessor(AudioStream stream, int sizeRequired) Chainable constructor.
WeightedWindowedAudioProcessor(AudioStream as, int nSamplesInWindow, int nSamplesOverlap) Chainable constructor that takes the size of the window and the number of samples overlap.
WeightedWindowedAudioProcessor(int sizeRequired) Default constructor for non chainable processing.
WeightedWindowedAudioProcessor(int nSamplesInWindow, int nSamplesOverlap) Constructor that takes the size of the window and the number of samples overlap.

Method Summary

Modifier and Type	Method and Description
protected abstract void	generateWeightTableCache(int length, int nc) Generate the cos table cache
double[]	getWeights() Get the weights used.
double	getWindowSum(int length, int numChannels) Get the sum of the Hanning window for the given parameters
double	getWindowSum(SampleChunk samples) The sum of the Hanning window
SampleBuffer	process(SampleBuffer b) Process the given sample buffer with the Hanning window.
SampleChunk	process(SampleChunk sample) Process the given sample chunk.
SampleChunk	processSamples(SampleChunk sample) Process the Hanning samples.

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

getWindowSize, getWindowStep, isOverlapping, nextSampleChunk, setWindowSize, setWindowStep

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

getLength, getUnderlyingStream, process, processingComplete, reset, setUnderlyingStream

Methods inherited from class org.openimaj.audio.AudioStream

iterator, 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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

weightTable

protected double[] weightTable

A table of weights

useWeights

protected boolean useWeights

Whether to apply the weights to the incoming signal

Constructor Detail

WeightedWindowedAudioProcessor

public WeightedWindowedAudioProcessor(int sizeRequired)

Default constructor for non chainable processing.

Parameters:

sizeRequired - Size of the window required

WeightedWindowedAudioProcessor

public WeightedWindowedAudioProcessor(AudioStream stream,
                                      int sizeRequired)

Chainable constructor. Takes the audio stream and the size required.

Parameters:

stream - The audio stream to process

sizeRequired - The size of window required.

WeightedWindowedAudioProcessor

public WeightedWindowedAudioProcessor(int nSamplesInWindow,
                                      int nSamplesOverlap)

Constructor that takes the size of the window and the number of samples overlap.

Parameters:

nSamplesInWindow - Samples in window

nSamplesOverlap - Samples in window overlap

WeightedWindowedAudioProcessor

public WeightedWindowedAudioProcessor(AudioStream as,
                                      int nSamplesInWindow,
                                      int nSamplesOverlap)

Chainable constructor that takes the size of the window and the number of samples overlap.

Parameters:

as - The chained audio stream

nSamplesInWindow - Samples in window

nSamplesOverlap - Samples in window overlap

Method Detail

generateWeightTableCache

protected abstract void generateWeightTableCache(int length,
                                                 int nc)

Generate the cos table cache

Parameters:

length - The length of the window to generate (per channel)

nc - The number of channels for which to generate a weight table

process

public final SampleChunk process(SampleChunk sample)

Process the given sample chunk. Note that it is expected that the sample will be the correct length (as given in the constructor). If it is not, the window will not be applied correctly. 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. The default operation of the FixedSizeSampleAudioProcessor is simply to change the shape of the sample chunk. You may override this method to process the samples directly.

Overrides:

process in class FixedSizeSampleAudioProcessor

Parameters:

sample - The sample chunk to process.

Returns:

A sample chunk containing processed data.

See Also:

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

process

public final SampleBuffer process(SampleBuffer b)

Process the given sample buffer with the Hanning window.

Parameters:

b - The sample buffer

Returns:

The sample buffer

processSamples

public SampleChunk processSamples(SampleChunk sample)

Process the Hanning samples.

Parameters:

sample - The samples to process

Returns:

The processed samples

getWindowSum

public double getWindowSum(SampleChunk samples)

The sum of the Hanning window

Parameters:

samples - A representative sample

Returns:

The sum of the hanning window

getWindowSum

public double getWindowSum(int length,
                           int numChannels)

Get the sum of the Hanning window for the given parameters

Parameters:

length - The length of the window

numChannels - The number of channels in the window

Returns:

The sum of the window

getWeights

public double[] getWeights()

Get the weights used.

Returns:

The weights