'\" te
.\" Copyright (c) 2007, Sun Microsystems, Inc.  All Rights Reserved 
.TH mlib_SignalLPCPitchAnalyze_F32 3MLIB "2 Mar 2007" "SunOS 5.11" "mediaLib Library Functions"
.SH NAME
mlib_SignalLPCPitchAnalyze_F32 \- perform open-loop pitch analysis
.SH SYNOPSIS
.LP
.nf
cc [ \fIflag\fR... ] \fIfile\fR... \fB-lmlib\fR [ \fIlibrary\fR... ]
#include <mlib.h>

\fBmlib_status\fR \fBmlib_SignalLPCPitchAnalyze_F32\fR(\fBmlib_s32 *\fR\fIpitch\fR,
     \fBconst mlib_f32 *\fR\fIsigwgt\fR, \fBconst mlib_s32 *\fR\fIregion\fR,
     \fBmlib_s32\fR \fIlength\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBmlib_SignalLPCPitchAnalyze_F32()\fR function performs open-loop pitch analysis.
.sp
.LP
The open-loop pitch analysis uses perceptual weighted signal and is done with following steps.
.sp
.LP
In the first step, three maxima of the correlation
.sp
.in +2
.nf
	       N-1
	R(k) = SUM sw(j) * sw(j-k)
	       j=0
.fi
.in -2

.sp
.LP
where \fBN = length\fR, is located for each of the three search regions.
.sp
.LP
In the second step, the retained maxima \fBR(Ti), i=0,1,2\fR are normalized as following.
.sp
.in +2
.nf
	                  R(Ti)
	Rn(ti) = ---------------------, i=0,1,2
	               N-1         2
	          SQRT(SUM sw(j-Ti) )
	               j=0
.fi
.in -2

.sp
.LP
where \fBN = length\fR.
.sp
.LP
In the third step, the best open-loop delay \fBTopt\fR is determined as following.
.sp
.in +2
.nf
	Topt = T0
	if (Rn(t1) \(>= (0.85 * Rn(Topt))
		Topt = t1
	if (Rn(t2) \(>= (0.85 * Rn(Topt))
		Topt = t2
.fi
.in -2

.sp
.LP
See G.729, G.729A, GSM EFR standards.
.SH PARAMETERS
.sp
.LP
The function takes the following arguments:
.sp
.ne 2
.mk
.na
\fB\fIpitch\fR\fR
.ad
.RS 10n
.rt  
The speech pitch estimated.
.RE

.sp
.ne 2
.mk
.na
\fB\fIsigwgt\fR\fR
.ad
.RS 10n
.rt  
The weighted signal vector. \fBsigwgt\fR points to the current sample of the weighted signal vector, \fBlength\fR samples must be availabe after this point, and \fBMAX{region[i],i=0,1,...,5}\fR samples must be available before this point.
.RE

.sp
.ne 2
.mk
.na
\fB\fIregion\fR\fR
.ad
.RS 10n
.rt  
The lower/upper boundaries of the three search regions, where \fBregion[2*i]\fR is the lower boundary of search region \fBi\fR and \fBregion[2*i+1]\fR is the upper boundary of search region \fBi\fR.
.RE

.sp
.ne 2
.mk
.na
\fB\fIlength\fR\fR
.ad
.RS 10n
.rt  
The length of the signal vectors over which the correlation is calculated.
.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_SignalLPCPitchAnalyze_S16\fR(3MLIB), \fBattributes\fR(5)