Public Member Functions | Static Public Member Functions | Private Member Functions | Private Attributes | List of all members
Decimator Class Reference

Decimator carries out a fast downsample by a power-of-two factor. More...

#include <Decimator.h>

Public Member Functions

 Decimator (int inLength, int decFactor)
 Construct a Decimator to operate on input blocks of length inLength, with decimation factor decFactor. More...
 
virtual ~Decimator ()
 
void process (const double *src, double *dst)
 Process inLength samples (as supplied to constructor) from src and write inLength / decFactor samples to dst. More...
 
void process (const float *src, float *dst)
 Process inLength samples (as supplied to constructor) from src and write inLength / decFactor samples to dst. More...
 
int getFactor () const
 
void resetFilter ()
 

Static Public Member Functions

static int getHighestSupportedFactor ()
 

Private Member Functions

void deInitialise ()
 
void initialise (int inLength, int decFactor)
 
void doAntiAlias (const double *src, double *dst, int length)
 
void doAntiAlias (const float *src, double *dst, int length)
 

Private Attributes

int m_inputLength
 
int m_outputLength
 
int m_decFactor
 
double Input
 
double Output
 
double o1
 
double o2
 
double o3
 
double o4
 
double o5
 
double o6
 
double o7
 
double a [9]
 
double b [9]
 
double * decBuffer
 

Detailed Description

Decimator carries out a fast downsample by a power-of-two factor.

Only a limited number of factors are supported, from two to whatever getHighestSupportedFactor() returns. This is much faster than Resampler but has a worse signal-noise ratio.

Definition at line 24 of file Decimator.h.

Constructor & Destructor Documentation

Decimator::Decimator ( int  inLength,
int  decFactor 
)

Construct a Decimator to operate on input blocks of length inLength, with decimation factor decFactor.

inLength should be a multiple of decFactor. Output blocks will be of length inLength / decFactor.

decFactor must be a power of two. The highest supported factor is obtained through getHighestSupportedFactor(); for higher factors, you will need to chain more than one decimator.

Definition at line 24 of file Decimator.cpp.

References initialise(), m_decFactor, m_inputLength, and m_outputLength.

Decimator::~Decimator ( )
virtual

Definition at line 33 of file Decimator.cpp.

References deInitialise().

Member Function Documentation

void Decimator::process ( const double *  src,
double *  dst 
)

Process inLength samples (as supplied to constructor) from src and write inLength / decFactor samples to dst.

Note that src and dst may be the same or overlap (an intermediate buffer is used).

Definition at line 195 of file Decimator.cpp.

References decBuffer, doAntiAlias(), m_decFactor, m_inputLength, and m_outputLength.

Referenced by ClusterMeltSegmenter::extractFeaturesConstQ(), ClusterMeltSegmenter::extractFeaturesMFCC(), GetKeyMode::process(), and DownBeat::pushAudioBlock().

void Decimator::process ( const float *  src,
float *  dst 
)

Process inLength samples (as supplied to constructor) from src and write inLength / decFactor samples to dst.

Note that src and dst may be the same or overlap (an intermediate buffer is used).

Definition at line 213 of file Decimator.cpp.

References decBuffer, doAntiAlias(), m_decFactor, m_inputLength, and m_outputLength.

int Decimator::getFactor ( ) const
inline

Definition at line 56 of file Decimator.h.

References m_decFactor.

Referenced by ClusterMeltSegmenter::extractFeaturesConstQ(), and ClusterMeltSegmenter::extractFeaturesMFCC().

static int Decimator::getHighestSupportedFactor ( )
inlinestatic

Definition at line 57 of file Decimator.h.

References deInitialise(), doAntiAlias(), initialise(), and resetFilter().

Referenced by ClusterMeltSegmenter::initialise(), and DownBeat::makeDecimators().

void Decimator::resetFilter ( )

Definition at line 148 of file Decimator.cpp.

References Input, o1, o2, o3, o4, o5, o6, o7, and Output.

Referenced by getHighestSupportedFactor(), and initialise().

void Decimator::deInitialise ( )
private

Definition at line 143 of file Decimator.cpp.

References decBuffer.

Referenced by getHighestSupportedFactor(), and ~Decimator().

void Decimator::initialise ( int  inLength,
int  decFactor 
)
private

Definition at line 38 of file Decimator.cpp.

References a, b, decBuffer, m_decFactor, m_inputLength, m_outputLength, and resetFilter().

Referenced by Decimator(), and getHighestSupportedFactor().

void Decimator::doAntiAlias ( const double *  src,
double *  dst,
int  length 
)
private

Definition at line 155 of file Decimator.cpp.

References a, b, Input, o1, o2, o3, o4, o5, o6, o7, and Output.

Referenced by getHighestSupportedFactor(), and process().

void Decimator::doAntiAlias ( const float *  src,
double *  dst,
int  length 
)
private

Definition at line 175 of file Decimator.cpp.

References a, b, Input, o1, o2, o3, o4, o5, o6, o7, and Output.

Member Data Documentation

int Decimator::m_inputLength
private

Definition at line 67 of file Decimator.h.

Referenced by Decimator(), initialise(), and process().

int Decimator::m_outputLength
private

Definition at line 68 of file Decimator.h.

Referenced by Decimator(), initialise(), and process().

int Decimator::m_decFactor
private

Definition at line 69 of file Decimator.h.

Referenced by Decimator(), getFactor(), initialise(), and process().

double Decimator::Input
private

Definition at line 71 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::Output
private

Definition at line 72 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o1
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o2
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o3
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o4
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o5
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o6
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::o7
private

Definition at line 74 of file Decimator.h.

Referenced by doAntiAlias(), and resetFilter().

double Decimator::a[9]
private

Definition at line 76 of file Decimator.h.

Referenced by doAntiAlias(), and initialise().

double Decimator::b[9]
private

Definition at line 77 of file Decimator.h.

Referenced by doAntiAlias(), and initialise().

double* Decimator::decBuffer
private

Definition at line 79 of file Decimator.h.

Referenced by deInitialise(), initialise(), and process().

The documentation for this class was generated from the following files:
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