Content-type: text/html Man page of mlib_SignalLPC2LSP_S16

# mlib_SignalLPC2LSP_S16

Section: mediaLib Library Functions (3MLIB)
Updated: 2 Mar 2007

## NAME

mlib_SignalLPC2LSP_S16 - convert linear prediction coefficients to line spectral pair coefficients

## SYNOPSIS

```cc [ flag... ] file... -lmlib [ library... ]
#include <mlib.h>

mlib_status mlib_SignalLPC2LSP_S16(mlib_s16 *lsp, const mlib_s16 *lpc,
mlib_s32 lscale, mlib_s32 order);
```

## DESCRIPTION

The mlib_SignalLPC2LSP_S16() function converts linear prediction coefficients to line spectral pair coefficients.

The line spectral pair (LPS) coefficients are defined as the roots of the following two polynomials:

```                       -(M+1)     -1
P(z) = A(z) + z      * A(z  )

-(M+1)     -1
Q(z) = A(z) - z      * A(z  )
```

where A(z) is the inverse filter

```                   M          -i
A(z) = 1- SUM a(i) * z
i=1
```

Note that since P(z) is symmetric and Q(z) is antisymmetric all roots of these polynomials are on the unit circle and they alternate each other. P(z) has a root at z = -1 (w = PI) and Q(z) has a root at z = 1 (w = 0).

The line spectral frequency (LPF) are the angular frequency of the line spectral pair (LPS) coefficients.

```        q = cos(w)
```

where q is the LPS and w is the LPF.

See Fundamentals of Speech Recognition by Lawrence Rabiner and Biing-Hwang Juang, Prentice Hall, 1993.

## PARAMETERS

The function takes the following arguments:

lsp

The line spectral pair coefficients in Q15 format.

lpc

The linear prediction coefficients.

lscale

The scaling factor of the linear prediction coefficients, where actual_data = input_data * 2**(-scaling_factor).

order

The order of the linear prediction filter.

## RETURN VALUES

The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

## ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

 ATTRIBUTE TYPE ATTRIBUTE VALUE Interface Stability Committed MT-Level

mlib_SignalLSP2LPC_S16(3MLIB), attributes(5)

NAME
SYNOPSIS
DESCRIPTION
PARAMETERS
RETURN VALUES
ATTRIBUTES