helpfun.c File Reference

#include <math.h>
#include "iLBC_define.h"
#include "constants.h"

Include dependency graph for helpfun.c:

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Functions
void	autocorr (float *r, const float *x, int N, int order)
void	bwexpand (float *out, float *in, float coef, int length)
void	interpolate (float *out, float *in1, float *in2, float coef, int length)
void	levdurb (float *a, float *k, float *r, int order)
int	LSF_check (float *lsf, int dim, int NoAn)
void	sort_sq (float *xq, int *index, float x, const float *cb, int cb_size)
void	SplitVQ (float *qX, int *index, float *X, const float *CB, int nsplit, const int *dim, const int *cbsize)
void	vq (float *Xq, int *index, const float *CB, float *X, int n_cb, int dim)
void	window (float *z, const float *x, const float *y, int N)

Function Documentation

autocorr()

void autocorr	(	float *	r,
		const float *	x,
		int	N,
		int	order
	)

Definition at line 22 of file helpfun.c.

References order.

Referenced by SimpleAnalysis().

 {
 int lag, n;
 float sum;

 for (lag = 0; lag <= order; lag++) {
 sum = 0;
 for (n = 0; n < N - lag; n++) {
 sum += x[n] * x[n+lag];
 }
 r[lag] = sum;
 }





 }

bwexpand()

void bwexpand	(	float *	out,
		float *	in,
		float	coef,
		int	length
	)

Definition at line 136 of file helpfun.c.

Referenced by DecoderInterpolateLSF(), SimpleAnalysis(), and SimpleInterpolateLSF().

 {
 int i;





 float chirp;

 chirp = coef;

 out[0] = in[0];
 for (i = 1; i < length; i++) {
 out[i] = chirp * in[i];
 chirp *= coef;
 }
 }

interpolate()

void interpolate	(	float *	out,
		float *	in1,
		float *	in2,
		float	coef,
		int	length
	)

Definition at line 114 of file helpfun.c.

Referenced by LSFinterpolate2a_dec(), and LSFinterpolate2a_enc().

 {
 int i;
 float invcoef;

 invcoef = (float)1.0 - coef;
 for (i = 0; i < length; i++) {
 out[i] = coef * in1[i] + invcoef * in2[i];
 }
 }

levdurb()

void levdurb	(	float *	a,
		float *	k,
		float *	r,
		int	order
	)

Definition at line 67 of file helpfun.c.

References EPS, and order.

Referenced by SimpleAnalysis().

 {
 float sum, alpha;
 int m, m_h, i;

 a[0] = 1.0;

 if (r[0] < EPS) { /* if r[0] <= 0, set LPC coeff. to zero */
 for (i = 0; i < order; i++) {
 k[i] = 0;
 a[i+1] = 0;
 }
 } else {
 a[1] = k[0] = -r[1]/r[0];
 alpha = r[0] + r[1] * k[0];
 for (m = 1; m < order; m++){
 sum = r[m + 1];
 for (i = 0; i < m; i++){
 sum += a[i+1] * r[m - i];
 }





 k[m] = -sum / alpha;
 alpha += k[m] * sum;
 m_h = (m + 1) >> 1;
 for (i = 0; i < m_h; i++){
 sum = a[i+1] + k[m] * a[m - i];
 a[m - i] += k[m] * a[i+1];
 a[i+1] = sum;
 }
 a[m+1] = k[m];
 }
 }
 }

LSF_check()

int LSF_check	(	float *	lsf,
		int	dim,
		int	NoAn
	)

Definition at line 272 of file helpfun.c.

Referenced by iLBC_decode(), and LPCencode().

 {
 int k,n,m, Nit=2, change=0,pos;
 static float eps=(float)0.039; /* 50 Hz */
 static float eps2=(float)0.0195;
 static float maxlsf=(float)3.14; /* 4000 Hz */
 static float minlsf=(float)0.01; /* 0 Hz */

 /* LSF separation check*/

 for (n=0; n<Nit; n++) { /* Run through a couple of times */
 for (m=0; m<NoAn; m++) { /* Number of analyses per frame */
 for (k=0; k<(dim-1); k++) {
 pos=m*dim+k;

 if ((lsf[pos+1]-lsf[pos])<eps) {

 if (lsf[pos+1]<lsf[pos]) {
 lsf[pos+1]= lsf[pos]+eps2;
 lsf[pos]= lsf[pos+1]-eps2;
 } else {
 lsf[pos]-=eps2;
 lsf[pos+1]+=eps2;
 }
 change=1;





 }

 if (lsf[pos]<minlsf) {
 lsf[pos]=minlsf;
 change=1;
 }

 if (lsf[pos]>maxlsf) {
 lsf[pos]=maxlsf;
 change=1;
 }
 }
 }
 }

 return change;
 }

sort_sq()

void sort_sq	(	float *	xq,
		int *	index,
		float	x,
		const float *	cb,
		int	cb_size
	)

Definition at line 235 of file helpfun.c.

Referenced by AbsQuantW(), and StateSearchW().

 {
 int i;

 if (x <= cb[0]) {
 *index = 0;
 *xq = cb[0];
 } else {
 i = 0;
 while ((x > cb[i]) && i < cb_size - 1) {
 i++;





 }

 if (x > ((cb[i] + cb[i - 1])/2)) {
 *index = i;
 *xq = cb[i];
 } else {
 *index = i - 1;
 *xq = cb[i - 1];
 }
 }
 }

SplitVQ()

void SplitVQ	(	float *	qX,
		int *	index,
		float *	X,
		const float *	CB,
		int	nsplit,
		const int *	dim,
		const int *	cbsize
	)

Definition at line 209 of file helpfun.c.

References vq().

Referenced by SimplelsfQ().

 {
 int cb_pos, X_pos, i;

 cb_pos = 0;
 X_pos= 0;
 for (i = 0; i < nsplit; i++) {
 vq(qX + X_pos, index + i, CB + cb_pos, X + X_pos,
 cbsize[i], dim[i]);
 X_pos += dim[i];
 cb_pos += dim[i] * cbsize[i];
 }
 }

vq()

void vq	(	float *	Xq,
		int *	index,
		const float *	CB,
		float *	X,
		int	n_cb,
		int	dim
	)

Definition at line 165 of file helpfun.c.

References FLOAT_MAX, and tmp().

Referenced by SplitVQ().

 {
 int i, j;
 int pos, minindex;
 float dist, tmp, mindist;

 pos = 0;
 mindist = FLOAT_MAX;
 minindex = 0;
 for (j = 0; j < n_cb; j++) {
 dist = X[0] - CB[pos];
 dist *= dist;
 for (i = 1; i < dim; i++) {
 tmp = X[i] - CB[pos + i];
 dist += tmp*tmp;
 }

 if (dist < mindist) {
 mindist = dist;
 minindex = j;
 }
 pos += dim;
 }
 for (i = 0; i < dim; i++) {
 Xq[i] = CB[minindex*dim + i];
 }
 *index = minindex;





 }

window()

void window	(	float *	z,
		const float *	x,
		const float *	y,
		int	N
	)

Definition at line 50 of file helpfun.c.

 {
 int i;

 for (i = 0; i < N; i++) {
 z[i] = x[i] * y[i];
 }
 }