mlib_SignalLPCCovariance_F32(3MLIB)			    mediaLib Library Functions			       mlib_SignalLPCCovariance_F32(3MLIB)

NAME

       mlib_SignalLPCCovariance_F32 - perform linear predictive coding with covariance method

SYNOPSIS

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

       mlib_status mlib_SignalLPCCovariance_F32(mlib_f32 *coeff, const mlib_f32 *signal, void *state);

DESCRIPTION

       The mlib_SignalLPCCovariance_F32() function performs linear predictive coding with covariance 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 fil-
       ter. 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 covariance method, the coefficients can be obtained by solving following set of linear equations.

	     M
	    SUM a(i) * c(i,k) = c(0,k), k=1,...,M
	    i=1

       where

		     N-k-1
	    c(i,k) =  SUM s(j) * s(j+k-i)
		      j=0

       are the covariance coefficients of s(*), N is the length of the input speech vector.

       Note that the covariance matrix R is a symmetric matrix, and the equations can be solved efficiently with Cholesky decomposition method.

       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	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_SignalLPCCovarianceInit_F32(3MLIB), mlib_SignalLPCCovarianceFree_F32(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 			       mlib_SignalLPCCovariance_F32(3MLIB)