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 in general. The only real issue is an initial CMN estimation, for that some amount of frames are read initially and cmn estimation is calculated from them.

The properties that affect this processor are defined by the fields PROP_INITIAL_CMN_WINDOW, 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)
 

See Also:

BatchCMN

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	PROP_CMN_SHIFT_WINDOW The property for the CMN shifting window.
static java.lang.String	PROP_CMN_WINDOW The property for the live CMN window size.
static java.lang.String	PROP_INITIAL_CMN_WINDOW The property for the live CMN initial window size.

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

logger

Constructor Summary

Constructors

Constructor and Description
LiveCMN()
LiveCMN(double initialMean, int cmnWindow, int cmnShiftWindow, int initialCmnWindow)

Method Summary

Modifier and Type	Method and Description
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, setPredecessor

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

getName, initLogger, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

PROP_INITIAL_CMN_WINDOW

@S4Integer(defaultValue=200)
public static final java.lang.String PROP_INITIAL_CMN_WINDOW

The property for the live CMN initial window size.

See Also:

Constant Field Values

PROP_CMN_WINDOW

@S4Integer(defaultValue=300)
public static final java.lang.String PROP_CMN_WINDOW

The property for the live CMN window size.

See Also:

Constant Field Values

PROP_CMN_SHIFT_WINDOW

@S4Integer(defaultValue=400)
public static final java.lang.String PROP_CMN_SHIFT_WINDOW

The property 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,
               int initialCmnWindow)

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