void find_aks(
float Sn[], /* Nsam samples with order sample memory */
float a[], /* order+1 LPCs with first coeff 1.0 */
int Nsam, /* number of input speech samples */
int order, /* order of the LPC analysis */
float *E /* residual energy */
)
{
float Wn[LPC_MAX_N]; /* windowed frame of Nsam speech samples */
float R[LPC_MAX+1]; /* order+1 autocorrelation values of Sn[] */
int i;
assert(order < LPC_MAX);
assert(Nsam < LPC_MAX_N);
hanning_window(Sn,Wn,Nsam);
autocorrelate(Wn,R,Nsam,order);
levinson_durbin(R,a,order);
*E = 0.0;
for(i=0; i<=order; i++)
*E += a[i]*R[i];
if (*E < 0.0)
*E = 1E-12;
}
void find_aks_for_lsp(
float Sn[], /* Nsam samples with order sample memory */
float a[], /* order+1 LPCs with first coeff 1.0 */
int Nsam, /* number of input speech samples */
int order, /* order of the LPC analysis */
float *E /* residual energy */
)
{
float Wn[N]; /* windowed frame of Nsam speech samples */
float R[P+1]; /* order+1 autocorrelation values of Sn[] */
int i;
hanning_window(Sn,Wn,Nsam);
autocorrelate(Wn,R,Nsam,order);
R[0] += LPC_FLOOR;
assert(order == 10); /* lag window only defined for order == 10 */
for(i=0; i<=order; i++)
R[i] *= lag_window[i];
levinson_durbin(R,a,order);
*E = 0.0;
for(i=0; i<=order; i++)
*E += a[i]*R[i];
if (*E < 0.0)
*E = 1E-12;
}
void find_aks(
scalar Sn[], /* Nsam samples with order sample memory */
scalar a[], /* order+1 LPCs with first coeff 1.0 */
int Nsam, /* number of input speech samples */
int order, /* order of the LPC analysis */
scalar *E /* residual energy */
)
{
scalar Wn[LPC_MAX_N]; /* windowed frame of Nsam speech samples */
scalar R[order+1]; /* order+1 autocorrelation values of Sn[] */
int i;
assert(Nsam < LPC_MAX_N);
hanning_window(Sn,Wn,Nsam);
autocorrelate(Wn,R,Nsam,order);
levinson_durbin(R,a,order);
*E = fl_to_numb(0.0);
for(i=0; i<=order; i++)
*E = s_add(*E , s_mul(a[i],R[i]));
if (*E < fl_to_numb(0.0)) {
#ifdef MATH_Q16_16
*E = 1;
#else
*E = powf(2, -16);//fl_to_numb(1E-12); For debuging purposes.
#endif
}
}