edu.cmu.sphinx.frontend.frequencywarp
Class PLPFrequencyFilterBank

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

All Implemented Interfaces:

DataProcessor, Configurable

public class PLPFrequencyFilterBank
extends BaseDataProcessor

Filters an input power spectrum through a PLP filterbank. The filters in the filterbank are placed in the frequency axis so as to mimic the critical band, representing different perceptual effect at different frequency bands. The filter outputs are also scaled for equal loudness preemphasis. The filter shapes are defined by the PLPFilter class. Like the MelFrequencyFilterBank, this filter bank has characteristics defined by the number of filters, the minimum frequency, and the maximum frequency. Unlike the MelFrequencyFilterBank, the minimum and maximum frequencies here refer to the center frequencies of the filters located at the leftmost and rightmost positions, and not to the edges. Therefore, this filter bank spans a frequency range that goes beyond the limits suggested by the minimum and maximum frequencies.

Version:

1.0

Author:

rsingh

See Also:

PLPFilter

Field Summary

static java.lang.String	PROP_MAX_FREQ The name of the Sphinx Property for the center frequency of the highest filter in the filterbank.
static java.lang.String	PROP_MIN_FREQ The name of the Sphinx Property for the center frequency of the lowest filter in the filterbank.
static java.lang.String	PROP_NUMBER_FILTERS The name of the Sphinx Property for the number of filters in the filterbank.

Constructor Summary

PLPFrequencyFilterBank()

PLPFrequencyFilterBank(double minFreq, double maxFreq, int numberFilters)

Method Summary

Data	getData() Reads the next Data object, which is the power spectrum of an audio input frame.
void	initialize() Initializes this PLPFrequencyFilterBank object
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 filterbank.

See Also:

Constant Field Values

PROP_MIN_FREQ

@S4Integer(defaultValue=130)
public static final java.lang.String PROP_MIN_FREQ

The name of the Sphinx Property for the center frequency of the lowest filter in the filterbank.

See Also:

Constant Field Values

PROP_MAX_FREQ

@S4Integer(defaultValue=3600)
public static final java.lang.String PROP_MAX_FREQ

The name of the Sphinx Property for the center frequency of the highest filter in the filterbank.

See Also:

Constant Field Values

Constructor Detail

PLPFrequencyFilterBank

public PLPFrequencyFilterBank(double minFreq,
                              double maxFreq,
                              int numberFilters)

PLPFrequencyFilterBank

public PLPFrequencyFilterBank()

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()

Initializes this PLPFrequencyFilterBank object

Specified by:

initialize in interface DataProcessor

Overrides:

initialize in class BaseDataProcessor

getData

public Data getData()
             throws DataProcessingException

Reads the next Data object, which is the power spectrum of an audio input frame. However, it can also be other Data objects like a Signal, which is returned unmodified.

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 a data processing error