marf.Preprocessing.FFTFilter
Class FFTFilter

java.lang.Object
  marf.Storage.StorageManager
      marf.Preprocessing.Preprocessing
          marf.Preprocessing.Filter
              marf.Preprocessing.FFTFilter.FFTFilter

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, IFilter, IPreprocessing, IStorageManager

Direct Known Subclasses:

BandpassFilter, BandStopFilter, HighFrequencyBoost, HighPassFilter, LowPassFilter

public abstract class FFTFilter
extends Filter

FFTFilter class implements filtering using the FFT algorithm.

Derivatives must set frequency response based on the type of filter they are.

$Id: FFTFilter.java,v 1.37 2007/12/16 21:58:31 mokhov Exp $

Since:

0.0.1

Version:

$Revision: 1.37 $

Author:

Stephen Sinclair, Serguei Mokhov

See Also:

Serialized Form

Field Summary

protected double[]	adFreqResponse Frequency response to be multiplied by the incoming value.
static int	DEFAULT_FREQUENCY_RESPONSE_SIZE Default size of the frequency response vector, 128.

Fields inherited from class marf.Preprocessing.Preprocessing

bRemoveNoise, bRemoveSilence, DEFAULT_SILENCE_THRESHOLD, dSilenceThreshold, oSample

Fields inherited from class marf.Storage.StorageManager

bDumpOnNotFound, iCurrentDumpMode, oObjectToSerialize, strFilename

Fields inherited from interface marf.Preprocessing.IFilter

FILTER_DIMENSIONALITY_1D, FILTER_DIMENSIONALITY_2D, FILTER_DIMENSIONALITY_3D, MARF_INTERFACE_CODE_REVISION

Fields inherited from interface marf.Preprocessing.IPreprocessing

MARF_INTERFACE_CODE_REVISION

Fields inherited from interface marf.Storage.IStorageManager

DUMP_BINARY, DUMP_CSV_TEXT, DUMP_GZIP_BINARY, DUMP_HTML, DUMP_SQL, DUMP_XML, MARF_INTERFACE_CODE_REVISION, STORAGE_FILE_EXTENSIONS

Constructor Summary

FFTFilter()
Default constructor for reflective creation of Preprocessing clones.

FFTFilter(IPreprocessing poPreprocessing)
Pipelined constructor.

FFTFilter(Sample poSample)
FFTFilter Constructor.

Method Summary

boolean	filter(double[][][] padSample, double[][][] padFiltered) Applies two-dimensional filtering to every plane of the matrix.
boolean	filter(double[][] padSample, double[][] padFiltered) Applies single-dimensional filtering to every row of the matrix.
boolean	filter(double[] padSample, double[] padFiltered) Perform a filter by the following algorithm: (1) sample -> window -> FFT -> buffer (2) buffer * frequency response (3) buffer -> IFFT -> window -> sample.
abstract void	generateResponseCoefficients() Creates frequency response coefficients and sets applies them to the frequency response vector.
static java.lang.String	getMARFSourceCodeRevision() Returns source code revision information.
boolean	preprocess() FFTFilter implementation of preprocess().
void	setFrequencyResponse(double[] padPesponse) Sets frequency response.

Methods inherited from class marf.Preprocessing.Preprocessing

backSynchronizeObject, clone, compress, compress, cropAudio, extractParameters, getSample, normalize, normalize, normalize, removeNoise, removeSilence, removeSilence, setSample

Methods inherited from class marf.Storage.StorageManager

dump, dumpBinary, dumpCSV, dumpGzipBinary, dumpHTML, dumpSQL, dumpXML, enableDumpOnNotFound, equals, getDefaultExtension, getDefaultExtension, getDumpMode, getFilename, getObjectToSerialize, hashCode, restore, restoreBinary, restoreCSV, restoreGzipBinary, restoreHTML, restoreSQL, restoreXML, setDumpMode, setFilename, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_FREQUENCY_RESPONSE_SIZE

public static final transient int DEFAULT_FREQUENCY_RESPONSE_SIZE

Default size of the frequency response vector, 128.

See Also:

Constant Field Values

adFreqResponse

protected transient double[] adFreqResponse

Frequency response to be multiplied by the incoming value.

Constructor Detail

FFTFilter

public FFTFilter()

Default constructor for reflective creation of Preprocessing clones. Typically should not be used unless really necessary for the frameworked modules.

Since:

0.3.0.5

FFTFilter

public FFTFilter(IPreprocessing poPreprocessing)
          throws PreprocessingException

Pipelined constructor.

Parameters:

poPreprocessing - the follow-up preprocessing module

Throws:

PreprocessingException

Since:

0.3.0.3

FFTFilter

public FFTFilter(Sample poSample)
          throws PreprocessingException

FFTFilter Constructor.

Parameters:

poSample - incoming sample

Throws:

PreprocessingException

Method Detail

preprocess

public boolean preprocess()
                   throws PreprocessingException

FFTFilter implementation of preprocess(). It overrides the default of Filter to allow a check for the frequency response array validation. NOTE: it alters inner Sample by resetting its data array to the new filtered values.

Specified by:

preprocess in interface IPreprocessing

Overrides:

preprocess in class Filter

Returns:

true if there was something filtered out

Throws:

PreprocessingException - primarily if the frequency response is null

See Also:

IPreprocessing.removeNoise(), IPreprocessing.removeSilence()

setFrequencyResponse

public final void setFrequencyResponse(double[] padPesponse)

Sets frequency response. Derivatives must call this method before any preprocessing occurs.

Parameters:

padPesponse - desired frequency response coefficients

filter

public final boolean filter(double[] padSample,
                            double[] padFiltered)
                     throws PreprocessingException

Perform a filter by the following algorithm: (1) sample -> window -> FFT -> buffer
(2) buffer * frequency response
(3) buffer -> IFFT -> window -> sample. Window used is square root of Hamming window, because the sum at half-window overlap is a constant, which avoids amplitude distortion from noise. Also, start sampling at -responseSize/2, in order to avoid amplitude distortion of the first half of the first window.

Parameters:

padSample - incoming sample analog data

padFiltered - will contain data after the filter was applied. "filtered" must be at least as long as "sample".

Returns:

true if some filtering actually happened

Throws:

PreprocessingException - if the filtered and sample data arrays are not of the same size, the frequency response was not set, or there was an underlying FeatureExctractionException while executing the underlying FFT algorithm.

filter

public boolean filter(double[][] padSample,
                      double[][] padFiltered)
               throws PreprocessingException

Applies single-dimensional filtering to every row of the matrix.

Parameters:

padSample - original sample to apply filtering to; should not be altered

padFiltered - buffer for filtered data

Returns:

true if filtering was successful and/or there were any changes

Throws:

PreprocessingException - if any error happened during filtering

Since:

0.3.0.6

See Also:

IFilter.filter(double[][], double[][]), filter(double[], double[])

filter

public boolean filter(double[][][] padSample,
                      double[][][] padFiltered)
               throws PreprocessingException

Applies two-dimensional filtering to every plane of the matrix.

Parameters:

padSample - original sample to apply filtering to; should not be altered

padFiltered - buffer for filtered data

Returns:

true if filtering was successful and/or there were any changes

Throws:

PreprocessingException - if any error happened during filtering

Since:

0.3.0.6

See Also:

IFilter.filter(double[][][], double[][][]), filter(double[][], double[][])

generateResponseCoefficients

public abstract void generateResponseCoefficients()

Creates frequency response coefficients and sets applies them to the frequency response vector. Must be overridden by individual filters.

Since:

0.3.0.2

getMARFSourceCodeRevision

public static java.lang.String getMARFSourceCodeRevision()

Returns source code revision information.

Returns:

revision string

Since:

0.3.0.2