Documentation

dsp.LPCToCepstral System object

Package: dsp

Convert linear prediction coefficients to cepstral coefficients

Description

The LPCToCepstral object converts linear prediction coefficients to cepstral coefficients.

To convert LPC to cepstral coefficients:

  1. Define and set up your LPC to cepstral converter. See Construction.

  2. Call step to convert LPC according to the properties of dsp.LPCToCepstral. The behavior of step is specific to each object in the toolbox.

Construction

H = dsp.LPCToCepstral returns an LPC to cepstral converter object, H, that converts linear prediction coefficients (LPCs) to cepstral coefficients (CCs).

H = dsp.LPCToCepstral('PropertyName',PropertyValue,...) returns an LPC to cepstral converter object, H, with each specified property set to the specified value.

Properties

PredictionErrorInputPort

Enable prediction error power input

Choose how to set the prediction error power. When you set this property to true, you must specify the prediction error as a second input to the step method. When you set this property to false, the object assumes the prediction error power is 1. The default is false.

CepstrumLengthSource

Source of cepstrum length

Select how to specify the length of cepstral coefficients: Auto or Property. The default is Auto. When this property is set to Auto, the length of each channel of the cepstral coefficients output is the same as the length of each channel of the input LPC coefficients. The default is Property.

CepstrumLength

Number of output cepstral coefficients

Set the length of the output cepstral coefficients vector as a scalar numeric integer. This property applies when you set the CepstrumLengthSource property to Property. The default is 10.

NonUnityFirstCoefficientAction

LPC coefficient nonunity action

Specify the action that the object takes when the first coefficient of each channel of the LPC input is not 1. Select Replace with 1 or Normalize. The default is Replace with 1.

Methods

cloneCreate LPC to cepstral object with same property values
getNumInputsNumber of expected inputs to step method
getNumOutputsNumber of outputs of step method
isLockedLocked status for input attributes and nontunable properties
releaseAllow property value and input characteristics changes
stepCepstral coefficients from columns of input LPC coefficients

Examples

Convert the linear prediction coefficients (LPC) to cepstral coefficients:

 hlevinson = dsp.LevinsonSolver;
 hlevinson.AOutputPort = true; % Output polynomial coefficients
 hac = dsp.Autocorrelator;
 hac.MaximumLagSource = 'Property';
 hac.MaximumLag = 9; % Compute autocorrelation lags between [0:9]
 hlpc2cc = dsp.LPCToCepstral;
 x = [1:100]';
 a = step(hac, x);
 A = step(hlevinson, a); % Compute LPC coefficients
 CC = step(hlpc2cc, A); % Convert LPC to CC.

Algorithms

This object implements the algorithm, inputs, and outputs described on the LPC to/from Cepstral Coefficients block reference page. The object properties correspond to the block parameters, except:

The object does not have a property that corresponds to the Type of Conversion block parameter. The object's behavior corresponds to the block's behavior when you set the Type of Conversion parameter to LPCs to cepstral coefficients.
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