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# mlib_signallpcpitchanalyze_f32(3mlib) [opensolaris man page]

```mlib_SignalLPCPitchAnalyze_F32(3MLIB)			    mediaLib Library Functions			     mlib_SignalLPCPitchAnalyze_F32(3MLIB)

NAME
mlib_SignalLPCPitchAnalyze_F32 - perform open-loop pitch analysis

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

mlib_status mlib_SignalLPCPitchAnalyze_F32(mlib_s32 *pitch,
const mlib_f32 *sigwgt, const mlib_s32 *region,
mlib_s32 length);

DESCRIPTION
The mlib_SignalLPCPitchAnalyze_F32() function performs open-loop pitch analysis.

The open-loop pitch analysis uses perceptual weighted signal and is done with following steps.

In the first step, three maxima of the correlation

N-1
R(k) = SUM sw(j) * sw(j-k)
j=0

where N = length, is located for each of the three search regions.

In the second step, the retained maxima R(Ti), i=0,1,2 are normalized as following.

R(Ti)
Rn(ti) = ---------------------, i=0,1,2
N-1	 2
SQRT(SUM sw(j-Ti) )
j=0

where N = length.

In the third step, the best open-loop delay Topt is determined as following.

Topt = T0
if (Rn(t1) >= (0.85 * Rn(Topt))
Topt = t1
if (Rn(t2) >= (0.85 * Rn(Topt))
Topt = t2

See G.729, G.729A, GSM EFR standards.

PARAMETERS
The function takes the following arguments:

pitch	 The speech pitch estimated.

sigwgt	 The  weighted	signal	vector. sigwgt points to the current sample of the weighted signal vector, length samples must be availabe
after this point, and MAX{region[i],i=0,1,...,5} samples must be available before this point.

region	 The lower/upper boundaries of the three search regions,  where  region[2*i]  is  the  lower  boundary	of  search  region  i  and
region[2*i+1] is the upper boundary of search region i.

length	 The length of the signal vectors over which the correlation is calculated.

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		     |MT-Safe			   |
+-----------------------------+-----------------------------+