'\" te
.\" Copyright (c) 2007, Sun Microsystems, Inc.  All Rights Reserved 
.TH mlib_SignalLSP2LPC_F32 3MLIB "2 Mar 2007" "SunOS 5.11" "mediaLib Library Functions"
.SH NAME
mlib_SignalLSP2LPC_F32 \- convert line spectral pair coefficients to linear prediction coefficients
.SH SYNOPSIS
.LP
.nf
cc [ \fIflag\fR... ] \fIfile\fR... \fB-lmlib\fR [ \fIlibrary\fR... ]
#include <mlib.h>

\fBmlib_status\fR \fBmlib_SignalLSP2LPC_F32\fR(\fBmlib_f32 *\fR\fIlpc\fR,
     \fBconst mlib_f32 *\fR\fIlsp\fR, \fBmlib_s32\fR \fIorder\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBmlib_SignalLSP2LPC_F32()\fR function converts line spectral pair coefficients to linear prediction coefficients.
.sp
.LP
The line spectral pair (LPS) coefficients are defined as the roots of the following two polynomials:
.sp
.in +2
.nf
	               -(M+1)     -1
	P(z) = A(z) + z      * A(z  )

	               -(M+1)     -1
	Q(z) = A(z) - z      * A(z  )
.fi
.in -2

.sp
.LP
where \fBA(z)\fR is the inverse filter
.sp
.in +2
.nf
	           M          -i
	A(z) = 1- SUM a(i) * z
	          i=1
.fi
.in -2

.sp
.LP
Note that since \fBP(z)\fR is symmetric and \fBQ(z)\fR is antisymmetric all roots of these polynomials are on the unit circle and they alternate each other. \fBP(z)\fR has a root at \fBz = -1\fR (\fBw = PI\fR) and \fBQ(z)\fR has a root at \fBz = 1\fR (\fBw = 0\fR).
.sp
.LP
The line spectral frequency (LPF) are the angular frequency of the line spectral pair (LPS) coefficients.
.sp
.in +2
.nf
	q = cos(w)
.fi
.in -2

.sp
.LP
where \fBq\fR is the LPS and w \fBis\fR the LPF.
.sp
.LP
See \fIFundamentals of Speech Recognition\fR by Lawrence Rabiner and Biing-Hwang Juang, Prentice Hall, 1993.
.SH PARAMETERS
.sp
.LP
The function takes the following arguments:
.sp
.ne 2
.mk
.na
\fB\fIlpc\fR\fR
.ad
.RS 9n
.rt  
The linear prediction coefficients.
.RE

.sp
.ne 2
.mk
.na
\fB\fIlsp\fR\fR
.ad
.RS 9n
.rt  
The line spectral pair coefficients.
.RE

.sp
.ne 2
.mk
.na
\fB\fIorder\fR\fR
.ad
.RS 9n
.rt  
The order of the linear prediction filter.
.RE

.SH RETURN VALUES
.sp
.LP
The function returns \fBMLIB_SUCCESS\fR if successful. Otherwise it returns \fBMLIB_FAILURE\fR.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityCommitted
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBmlib_SignalLPC2LSP_F32\fR(3MLIB), \fBattributes\fR(5)