Package: dsp
Convert linear prediction coefficients to line spectral pairs
The LPCToLSP
object converts linear prediction
coefficients to line spectral pairs.
To convert LPC to LSP:
Define and set up your LPC to LSP converter. See Construction.
Call step
to convert LPC according to the properties
of dsp.LPCToLSP
. The behavior of step
is
specific to each object in the toolbox.
Note:
Starting in R2016b, instead of using the 
H = dsp.LPCToLSP
returns
a System object, H
, that converts linear prediction
coefficients (LPCs) to line spectral pairs (LSPs).
H = dsp.LPCToLSP('
returns
an PropertyName
',PropertyValue
,...)LPC
to LSF
System object, H
,
with each specified property set to the specified value.

Number of coarse subintervals used for finding roots (LSP values) Specify the number of coarse subintervals, n,
used for finding line spectral pairs (LSP) values, as a positive scalar
integer. LSPs, which are the roots of two particular polynomials related
to the input LPC polynomial, always lie in the range (–1, 1).
The System object finds these roots using the Chebyshev polynomial
root finding method. The object divides the interval (–1, 1)
into n subintervals and looks for roots in each
subinterval. If n is set to too small a number
in relation to the LPC polynomial order, the object can fail to find
some of the roots. The default is 

Value of bisection refinement used for finding roots Specify the root bisection refinement value, k, that the Chebyshev polynomial uses in the root finding method. For each line spectral pair (LSP) the output is within $$\frac{\text{1}}{\text{n}\cdot {\text{2}}^{\text{k}}}$$ of the actual LSP
value. Here n is the value of the $$\text{k}\cdot \text{(n1)}$$ points for finding
the roots. The 

Produces output with validity status of LSP output Set this property to 

Enable overwriting invalid output with previous output Specify the action that the object takes for invalid LSP outputs.
When you set this property to 

Source of values for first output when output is invalid Specify the source of values for the first output when the output
is invalid as 

Value of first output Specify a numeric vector of LSP values for overwriting an invalid
first output. The length of this vector must be one less than the
length of the input LPC vector. For multichannel inputs, set this
property can to a matrix with the same number of channels as the input
or one vector that you apply to every channel. The default is an empty
vector. This property applies only when you set the 

First coefficient nonunity action Specify the action that the object takes when the first coefficient
of each channel of the LPC input is not equal to 
clone  Create LPC To LSP object with same property values 
getNumInputs  Number of expected inputs to step method 
getNumOutputs  Number of outputs of step method 
isLocked  Locked status for input attributes and nontunable properties 
release  Allow property value and input characteristics changes 
reset  Reset values for overwriting invalid outputs to their initial values 
step  Convert linear prediction coefficients to line spectral pairs 
This object implements the algorithm, inputs, and outputs described on the LPC to LSF/LSP Conversion block reference page. The object properties correspond to the block parameters, except:
No object property corresponds to the Output block parameter. The object only supports LSP outputs. 