LSF/LSP to LPC Conversion

R2026b

Convert line spectral frequencies or line spectral pairs to linear prediction coefficients

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LSF/LSP to LPC Conversion block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
DSP System Toolbox / Estimation / Linear Prediction

Description

The LSF/LSP to LPC Conversion block converts line spectral pairs (LSPs) or line spectral frequencies (LSFs) to linear prediction polynomial coefficients (LPCs). When converting LSFs to LPCs, the block outputs match those of the lsf2poly function.

Ports

Input

LSP — Line spectral pairs

vector | matrix

Specify the line spectral pairs as a vector of values in the range (−1 1) in decreasing order. If you specify a matrix, the block treats each column of the matrix as a separate channel. When you specify an unoriented vector, the block treats the input as one channel. These values equal the cosine of the LSF values between 0 and π radians. Do not include the guaranteed LSP values, −1 and 1.

Data Types: single | double

LSFn — Line spectral frequencies normalized in range (0 0.5)

vector | matrix

Specify the line spectral frequencies normalized in the range (0 0.5) as a vector or a matrix in increasing order. If you specify a matrix, the block treats each column of the matrix as a separate channel. When you specify an unoriented vector, the block treats the input as one channel. You can obtain these values by dividing the LSF values between 0 and π radians by 2π. Do not include the guaranteed LSF values, 0 and 0.5.

Data Types: single | double

LSFr — Line spectral frequencies in range (0 π)

vector | matrix

Specify the line spectral frequencies in the range (0 π) as a vector or a matrix in increasing order. If you specify a matrix, the block treats each column of the matrix as a separate channel. When you specify an unoriented vector, the block treats the input as one channel. Do not include the guaranteed LSF values, 0 and π.

Data Types: single | double

Output

A — Linear prediction coefficients

vector | matrix

Linear prediction coefficients, returned as a vector or a matrix.

Data Types: single | double

Parameters

Input — Line spectral pairs or line spectral frequencies

LSP in range (-1 1) (default) | LSF normalized in range (0 0.5) | LSF in range (0 pi)

When you select this parameter to:

• LSP in range (-1 1) — The block converts the line spectral pairs in the range (−1 1) to linear prediction coefficients.

• LSF in range (0 pi) — The block converts the line spectral frequencies in the range (0 π) to linear prediction coefficients.

• LSF normalized in range (0 0.5) — The block converts the line spectral frequencies normalized in the range (0 0.5) to linear prediction coefficients.

Block Characteristics

Data Types	double | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"dsplp/LSF//LSP to LPC Conversion"

Example: add_block("dsplp/LSF//LSP to LPC Conversion","myModel/myBlock",MakeNameUnique="on")

References

[1] Kabal, P. and Ramachandran, R. “The Computation of Line Spectral Frequencies Using Chebyshev Polynomials.” IEEE Transactions on Acoustics, Speech, and Signal Processing, Vol. ASSP-34 No. 6, December 1986. pp. 1419-1426.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a