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LSF/LSP to LPC Conversion

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


Estimation / Linear Prediction



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

The block input can be an N-by-M matrix or an unoriented vector. Each column of the matrix is treated as a channel. When the input is an unoriented vector, the input is treated as one channel. Each input channel must be in the same format, which you specify in the Input parameter:

  • LSF in range (0 pi) — Vector of LSF values between 0 and π radians in increasing order. Do not include the guaranteed LSF values, 0 and π.

  • LSF normalized in range (0 0.5) — Vector of normalized LSF values in increasing order, (compute by dividing the LSF values between 0 and π radians by 2π). Do not include the guaranteed normalized LSF values, 0 and 0.5.

  • LSP in range (-1 1) — Vector of LSP values in decreasing order, equal to the cosine of the LSF values between 0 and π radians. Do not include the guaranteed LSP values, -1 and 1.



Specifies whether to convert LSP in range (-1 1), LSF in range (0 pi), or LSF normalized in range (0 0.5) to linear prediction coefficients (LPCs).

Supported Data Types

  • Double-precision floating point

  • Single-precision floating point


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.

See Also

LPC to LSF/LSP ConversionDSP System Toolbox
LPC to/from RCDSP System Toolbox
LPC/RC to AutocorrelationDSP System Toolbox
lsf2polySignal Processing Toolbox

Introduced before R2006a

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