Content-type: text/html Man page of mlib_SignalLPCAutoCorrel_F32

# mlib_SignalLPCAutoCorrel_F32

Section: mediaLib Library Functions (3MLIB)
Updated: 2 Mar 2007
Index Return to Main Contents

## NAME

mlib_SignalLPCAutoCorrel_F32 - perform linear predictive coding with autocorrelation method

## SYNOPSIS

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

mlib_status mlib_SignalLPCAutoCorrel_F32(mlib_f32 *coeff,
const mlib_f32 *signal, void *state);
```

## DESCRIPTION

The mlib_SignalLPCAutoCorrel_F32() function performs linear predictive coding with autocorrelation method.

In linear predictive coding (LPC) model, each speech sample is represented as a linear combination of the past M samples.

```                M
s(n) = SUM a(i) * s(n-i) + G * u(n)
i=1
```

where s(*) is the speech signal, u(*) is the excitation signal, and G is the gain constants, M is the order of the linear prediction filter. Given s(*), the goal is to find a set of coefficient a(*) that minimizes the prediction error e(*).

```                       M
e(n) = s(n) - SUM a(i) * s(n-i)
i=1
```

In autocorrelation method, the coefficients can be obtained by solving following set of linear equations.

```         M
SUM a(i) * r(|i-k|) = r(k), k=1,...,M
i=1
```

where

```              N-k-1
r(k) = SUM s(j) * s(j+k)
j=0
```

are the autocorrelation coefficients of s(*), N is the length of the input speech vector. r(0) is the energy of the speech signal.

Note that the autocorrelation matrix R is a Toeplitz matrix (symmetric with all diagonal elements equal), and the equations can be solved efficiently with Levinson-Durbin algorithm.

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

## PARAMETERS

The function takes the following arguments:

coeff

The linear prediction coefficients.

signal

The input signal vector.

state

Pointer to the internal state structure.

## 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

## SEE ALSO

mlib_SignalLPCAutoCorrelInit_F32(3MLIB), mlib_SignalLPCAutoCorrelGetEnergy_F32(3MLIB), mlib_SignalLPCAutoCorrelGetPARCOR_F32(3MLIB), mlib_SignalLPCAutoCorrelFree_F32(3MLIB), attributes(5)

## Index

NAME
SYNOPSIS
DESCRIPTION
PARAMETERS
RETURN VALUES
ATTRIBUTES
SEE ALSO

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Time: 02:38:12 GMT, October 02, 2010