edu.cmu.sphinx.frontend.frequencywarp
Class PLPCepstrumProducer

java.lang.Object
  edu.cmu.sphinx.util.props.ConfigurableAdapter
      edu.cmu.sphinx.frontend.BaseDataProcessor
          edu.cmu.sphinx.frontend.frequencywarp.PLPCepstrumProducer

All Implemented Interfaces:

DataProcessor, Configurable

public class PLPCepstrumProducer
extends BaseDataProcessor

Computes the PLP cepstrum from a given PLP Spectrum. The power spectrum has the amplitude compressed by computing the cubed root of the PLP spectrum. This operation is an approximation to the power law of hearing and simulates the non-linear relationship between sound intensity and perceived loudness. Computationally, this operation is used to reduce the spectral amplitude of the critical band to enable all-pole modeling with relatively low order AR filters. The inverse discrete cosine transform (IDCT) is then applied to the autocorrelation coefficients. A linear prediction filter is then estimated from the autocorrelation values, and the linear prediction cepstrum (LPC cepstrum) is finally computed from the LP filter.

Version:

1.0

Author:

rsingh

See Also:

LinearPredictor

Field Summary

static java.lang.String	PROP_CEPSTRUM_LENGTH The SphinxProperty specifying the length of the cepstrum data.
static java.lang.String	PROP_LPC_ORDER The SphinxProperty specifying the LPC order.
static java.lang.String	PROP_NUMBER_FILTERS The name of the Sphinx Property for the number of filters in the filter bank.

Constructor Summary

PLPCepstrumProducer()

PLPCepstrumProducer(int numberPLPFilters, int cepstrumSize, int LPCOrder)

Method Summary

Data	getData() Returns the next Data object, which is the PLP cepstrum of the input frame.
void	initialize() Constructs a PLPCepstrumProducer
void	newProperties(PropertySheet ps) This method is called when this configurable component needs to be reconfigured.

Methods inherited from class edu.cmu.sphinx.frontend.BaseDataProcessor

getPredecessor, getTimer, setPredecessor

Methods inherited from class edu.cmu.sphinx.util.props.ConfigurableAdapter

getName, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

PROP_NUMBER_FILTERS

@S4Integer(defaultValue=32)
public static final java.lang.String PROP_NUMBER_FILTERS

The name of the Sphinx Property for the number of filters in the filter bank.

See Also:

Constant Field Values

PROP_CEPSTRUM_LENGTH

@S4Integer(defaultValue=13)
public static final java.lang.String PROP_CEPSTRUM_LENGTH

The SphinxProperty specifying the length of the cepstrum data.

See Also:

Constant Field Values

PROP_LPC_ORDER

@S4Integer(defaultValue=14)
public static final java.lang.String PROP_LPC_ORDER

The SphinxProperty specifying the LPC order.

See Also:

Constant Field Values

Constructor Detail

PLPCepstrumProducer

public PLPCepstrumProducer(int numberPLPFilters,
                           int cepstrumSize,
                           int LPCOrder)

PLPCepstrumProducer

public PLPCepstrumProducer()

Method Detail

newProperties

public void newProperties(PropertySheet ps)
                   throws PropertyException

Description copied from interface: Configurable

This method is called when this configurable component needs to be reconfigured.

Specified by:

newProperties in interface Configurable

Overrides:

newProperties in class ConfigurableAdapter

Parameters:

ps - a property sheet holding the new data

Throws:

PropertyException - if there is a problem with the properties.

initialize

public void initialize()

Constructs a PLPCepstrumProducer

Specified by:

initialize in interface DataProcessor

Overrides:

initialize in class BaseDataProcessor

getData

public Data getData()
             throws DataProcessingException

Returns the next Data object, which is the PLP cepstrum of the input frame. However, it can also be other Data objects like a EndPointSignal.

Specified by:

getData in interface DataProcessor

Specified by:

getData in class BaseDataProcessor

Returns:

the next available Data object, returns null if no Data object is available

Throws:

DataProcessingException - if there is an error reading the Data objects