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dsp.LPCToCepstral System object

Package: dsp

Convert linear prediction coefficients to cepstral coefficients


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.

    Note:   Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.


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.



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.


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.


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.


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.


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


expand all

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

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 = hac(x);

Compute LPC coefficients.

A = hlevinson(a);

Convert LPC to CC.

CC = hlpc2cc(A);


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.

Introduced in R2012a

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