org.openimaj.audio.processor

Class FixedSizeSampleAudioProcessor

java.lang.Object

org.openimaj.audio.Audio

org.openimaj.audio.AudioStream

org.openimaj.audio.processor.AudioProcessor

org.openimaj.audio.processor.FixedSizeSampleAudioProcessor

All Implemented Interfaces:

Iterable<SampleChunk>

Direct Known Subclasses:

EffectiveSoundPressure, FeedForwardCombFilter, FIRFilter, WeightedWindowedAudioProcessor

public class FixedSizeSampleAudioProcessor
extends AudioProcessor

Provides an audio processor that will process sample chunks of specific sizes when the incoming stream's sample chunk size is unknown.

This class has applications for FFT (for example) where the input sample size must be a power of 2 and the underlying audio stream reader may be returning sample chunks of any size.

The processor can also provide overlapping sample windows. Call setWindowStep(int) to determine the slide of each sliding window. If this is set to 0 or below, the windows will be consecutive and will not overlap.

The only assumption made by the class about the samples is that they are whole numbers of bytes (8, 16, 24, 32 bits etc.). This is a pretty reasonable assumption.

Author:

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

Created:

11 Jul 2011

Field Summary

Fields inherited from class org.openimaj.audio.Audio

format

Constructor Summary

Constructors

Constructor and Description
FixedSizeSampleAudioProcessor(AudioStream stream, int sizeRequired) Create processor that will process chunks of the given size.
FixedSizeSampleAudioProcessor(AudioStream as, int nSamplesInWindow, int nSamplesOverlap) Chainable constructor that takes the size of the window and the number of samples overlap.
FixedSizeSampleAudioProcessor(int sizeRequired) Create processor that will process chunks of the given size.
FixedSizeSampleAudioProcessor(int nSamplesInWindow, int nSamplesOverlap) Constructor that takes the size of the window and the size of the window overlap.

Method Summary

Modifier and Type	Method and Description
int	getWindowSize() Returns the size of the sample window.
int	getWindowStep() Returns the step of each overlapping window.
boolean	isOverlapping() Returns whether the windows are overlapping or not.
SampleChunk	nextSampleChunk() Retrieve the next SampleChunk from the audio stream.
SampleChunk	process(SampleChunk sample) Function that takes a sample chunk and processes the chunk.
void	setWindowSize(int sizeRequired) Set the size of the window required.
void	setWindowStep(int overlap) Set the step of each overlapping window.

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

Constructor Detail

FixedSizeSampleAudioProcessor

public FixedSizeSampleAudioProcessor(int sizeRequired)

Create processor that will process chunks of the given size.

Parameters:

sizeRequired - The size of the chunks required (in samples)

FixedSizeSampleAudioProcessor

public FixedSizeSampleAudioProcessor(AudioStream stream,
                                     int sizeRequired)

Create processor that will process chunks of the given size.

Parameters:

stream - An audio stream to process

sizeRequired - The size of the chunks required (in samples)

FixedSizeSampleAudioProcessor

public FixedSizeSampleAudioProcessor(int nSamplesInWindow,
                                     int nSamplesOverlap)

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

Parameters:

nSamplesInWindow - The number of samples in the window

nSamplesOverlap - The size of the overlap

FixedSizeSampleAudioProcessor

public FixedSizeSampleAudioProcessor(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

nextSampleChunk

public SampleChunk nextSampleChunk()

Retrieve the next SampleChunk from the audio stream.

Overrides:

nextSampleChunk in class AudioProcessor

Returns:

The next sample chunk in the audio stream.

See Also:

AudioProcessor.nextSampleChunk()

setWindowStep

public void setWindowStep(int overlap)

Set the step of each overlapping window.

Parameters:

overlap - The step of each overlapping window.

getWindowStep

public int getWindowStep()

Returns the step of each overlapping window.

Returns:

The step of each overlapping window.

setWindowSize

public void setWindowSize(int sizeRequired)

Set the size of the window required. Should be called before the object has been used to process anything. The result is undefined if it's called during processing and will probably lead to some sort of bounds error.

Parameters:

sizeRequired - The size required.

getWindowSize

public int getWindowSize()

Returns the size of the sample window.

Returns:

The size of the sample window.

isOverlapping

public boolean isOverlapping()

Returns whether the windows are overlapping or not.

Returns:

whether the windows are overlapping or not.

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. 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.

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)