org.openimaj.audio.processor

Class AudioProcessor

java.lang.Object

org.openimaj.audio.Audio

org.openimaj.audio.AudioStream

org.openimaj.audio.processor.AudioProcessor

All Implemented Interfaces:

Iterable<SampleChunk>

Direct Known Subclasses:

AudioConverter, AudioOverviewVisualisation.AudioOverviewGenerator, BeatDetector, BitDepthConverter, EQFilter, FFTBandPassFilter, FixedSizeSampleAudioProcessor, FourierTransform, FrequencyAudioSource, JAudioFeatureExtractor, MultichannelToMonoProcessor, MusicalNoteFilterBank, MusicalNoteOnsetDetector, PeakNormalisationCalculator, PowerCepstrumTransform, Preemphasiser, SampleRateConverter, VolumeAdjustProcessor

public abstract class AudioProcessor
extends AudioStream

An interface for objects that are able to process audio sample data. Due to the fact that audio processors provide processed audio, they are also able to implement the AudioStream interface thereby making processors chainable.

Author:

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

Created:

8 Jun 2011

Field Summary

Fields inherited from class org.openimaj.audio.Audio

format

Constructor Summary

Constructors

Constructor and Description
AudioProcessor() A default constructor for processing sample chunks or files in an ad-hoc manner.
AudioProcessor(AudioStream a) Construct a new processor based on the given stream.

Method Summary

Modifier and Type	Method and Description
long	getLength() Returns the length of the audio stream in milliseconds.
AudioStream	getUnderlyingStream() Get the underlying stream.
SampleChunk	nextSampleChunk() Retrieve the next SampleChunk from the audio stream.
void	process(AudioStream a) Function to process a whole audio stream.
abstract SampleChunk	process(SampleChunk sample) Function that takes a sample chunk and processes the chunk.
void	processingComplete(AudioStream a) Called when the processing of a given audio stream has been completed.
void	reset() Reset the audio stream.
void	setUnderlyingStream(AudioStream stream) Sets the underlying stream, allowing it to be changed.

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

AudioProcessor

public AudioProcessor()

A default constructor for processing sample chunks or files in an ad-hoc manner.

AudioProcessor

public AudioProcessor(AudioStream a)

Construct a new processor based on the given stream. This processor can then be used as a stream itself in a chain.

Parameters:

a - The audio stream to process.

Method Detail

process

public void process(AudioStream a)
             throws Exception

Function to process a whole audio stream. If the process returns null, it will stop the processing of the audio stream. Note that the output of the audio stream processing is not stored (it may be a live stream and so would be too large to store), so the caller must interact with the audio processor themselves to retrieve any useful information from the processing.

Parameters:

a - The audio stream to process.

Throws:

Exception - If the processing failed

process

public abstract 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.

Parameters:

sample - The sample chunk to process.

Returns:

A sample chunk containing processed data.

Throws:

Exception - If the processing could not take place

processingComplete

public void processingComplete(AudioStream a)

Called when the processing of a given audio stream has been completed. This can be used to alter the audio stream's properties.

Parameters:

a - The audio stream that has finished processing.

nextSampleChunk

public SampleChunk nextSampleChunk()

Retrieve the next SampleChunk from the audio stream.

Specified by:

nextSampleChunk in class AudioStream

Returns:

The next sample chunk in the audio stream.

See Also:

AudioStream.nextSampleChunk()

getUnderlyingStream

public AudioStream getUnderlyingStream()

Get the underlying stream. Will return null for non-chained audio processors.

Returns:

The underlying stream on chained processors.

setUnderlyingStream

public void setUnderlyingStream(AudioStream stream)

Sets the underlying stream, allowing it to be changed.

Parameters:

stream - The stream

reset

public void reset()

Reset the audio stream. The implementation in this class just calls reset on the wrapped stream (if it's set).

Specified by:

reset in class AudioStream

See Also:

AudioStream.reset()

getLength

public long getLength()

Returns the length of the audio stream in milliseconds. If the length is unknown (for a live stream for example), then this method should return -1.

Specified by:

getLength in class AudioStream

Returns:

The length in milliseconds, or -1

See Also:

AudioStream.getLength()