edu.cmu.sphinx.frontend.feature
Class LiveCMN

java.lang.Object
  edu.cmu.sphinx.util.props.ConfigurableAdapter
      edu.cmu.sphinx.frontend.BaseDataProcessor
          edu.cmu.sphinx.frontend.feature.LiveCMN

All Implemented Interfaces:

DataProcessor, Configurable

public class LiveCMN
extends BaseDataProcessor

Subtracts the mean of all the input so far from the Data objects. Unlike the BatchCMN, it does not read in the entire stream of Data objects before it calculates the mean. It estimates the mean from already seen data and subtracts the mean from the Data objects on the fly. Therefore, there is no delay introduced by LiveCMN.

The Sphinx properties that affect this processor are defined by the fields PROP_INITIAL_MEAN, PROP_CMN_WINDOW, and PROP_CMN_SHIFT_WINDOW. Please follow the link "Constant Field Values" below to see the actual name of the Sphinx properties.

The mean of all the input cepstrum so far is not reestimated for each cepstrum. This mean is recalculated after every PROP_CMN_SHIFT_WINDOW cepstra. This mean is estimated by dividing the sum of all input cepstrum so far. After obtaining the mean, the sum is exponentially decayed by multiplying it by the ratio:

 cmnWindow/(cmnWindow + number of frames since the last recalculation)
 

This is a 1-to-1 processor.

See Also:

BatchCMN

Field Summary

static java.lang.String	PROP_CMN_SHIFT_WINDOW The name of the SphinxProperty for the CMN shifting window.
static java.lang.String	PROP_CMN_WINDOW The name of the SphinxProperty for the live CMN window size.
static java.lang.String	PROP_INITIAL_MEAN The name of the SphinxProperty for the initial cepstral mean.

Constructor Summary

LiveCMN()

LiveCMN(double initialMean, int cmnWindow, int cmnShiftWindow)

Method Summary

Data	getData() Returns the next Data object, which is a normalized Data produced by this class.
void	initialize() Initializes this LiveCMN.
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_INITIAL_MEAN

@S4Double(defaultValue=12.0)
public static final java.lang.String PROP_INITIAL_MEAN

The name of the SphinxProperty for the initial cepstral mean. This is a front-end dependent magic number.

See Also:

Constant Field Values

PROP_CMN_WINDOW

@S4Integer(defaultValue=100)
public static final java.lang.String PROP_CMN_WINDOW

The name of the SphinxProperty for the live CMN window size.

See Also:

Constant Field Values

PROP_CMN_SHIFT_WINDOW

@S4Integer(defaultValue=160)
public static final java.lang.String PROP_CMN_SHIFT_WINDOW

The name of the SphinxProperty for the CMN shifting window. The shifting window specifies how many cepstrum after which we re-calculate the cepstral mean.

See Also:

Constant Field Values

Constructor Detail

LiveCMN

public LiveCMN(double initialMean,
               int cmnWindow,
               int cmnShiftWindow)

LiveCMN

public LiveCMN()

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 LiveCMN.

Specified by:

initialize in interface DataProcessor

Overrides:

initialize in class BaseDataProcessor

getData

public Data getData()
             throws DataProcessingException

Returns the next Data object, which is a normalized Data produced by this class. Signals are 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