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Dmytro Bogovych
2018-06-05 11:05:37 +03:00
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/*
ITU-T G.729A Speech Coder ANSI-C Source Code
Version 1.1 Last modified: September 1996
Copyright (c) 1996,
AT&T, France Telecom, NTT, Universite de Sherbrooke
All rights reserved.
*/
/*-----------------------------------------------------*
* Function Autocorr() *
* *
* Compute autocorrelations of signal with windowing *
* *
*-----------------------------------------------------*/
#include "g729_typedef.h"
#include "g729_basic_op.h"
#include "g729_oper_32b.h"
#include "g729_ld8a.h"
#include "g729_tab_ld8a.h"
void
Autocorr (Word16 x[], /* (i) : Input signal */
Word16 m, /* (i) : LPC order */
Word16 r_h[], /* (o) : Autocorrelations (msb) */
Word16 r_l[] /* (o) : Autocorrelations (lsb) */
)
{
Word16 i, j, norm;
Word16 y[L_WINDOW];
Word32 sum;
Flag Overflow;
/* Windowing of signal */
for (i = 0; i < L_WINDOW; i++) {
y[i] = mult_r (x[i], hamwindow[i]);
}
/* Compute r[0] and test for overflow */
do {
Overflow = 0;
sum = 1; /* Avoid case of all zeros */
for (i = 0; i < L_WINDOW; i++)
sum = L_mac_o (sum, y[i], y[i], &Overflow);
/* If overflow divide y[] by 4 */
if (Overflow != 0) {
for (i = 0; i < L_WINDOW; i++) {
y[i] = shr (y[i], 2);
}
}
} while (Overflow != 0);
/* Normalization of r[0] */
norm = norm_l (sum);
sum = L_shl (sum, norm);
L_Extract (sum, &r_h[0], &r_l[0]); /* Put in DPF format (see oper_32b) */
/* r[1] to r[m] */
for (i = 1; i <= m; i++) {
sum = 0;
for (j = 0; j < L_WINDOW - i; j++)
sum = L_mac (sum, y[j], y[j + i]);
sum = L_shl (sum, norm);
L_Extract (sum, &r_h[i], &r_l[i]);
}
return;
}
/*-------------------------------------------------------*
* Function Lag_window() *
* *
* Lag_window on autocorrelations. *
* *
* r[i] *= lag_wind[i] *
* *
* r[i] and lag_wind[i] are in special double precision.*
* See "oper_32b.c" for the format *
* *
*-------------------------------------------------------*/
void
Lag_window (Word16 m, /* (i) : LPC order */
Word16 r_h[], /* (i/o) : Autocorrelations (msb) */
Word16 r_l[] /* (i/o) : Autocorrelations (lsb) */
)
{
Word16 i;
Word32 x;
for (i = 1; i <= m; i++) {
x = Mpy_32 (r_h[i], r_l[i], lag_h[i - 1], lag_l[i - 1]);
L_Extract (x, &r_h[i], &r_l[i]);
}
return;
}
/*___________________________________________________________________________
| |
| LEVINSON-DURBIN algorithm in double precision |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
|---------------------------------------------------------------------------|
| |
| Algorithm |
| |
| R[i] autocorrelations. |
| A[i] filter coefficients. |
| K reflection coefficients. |
| Alpha prediction gain. |
| |
| Initialization: |
| A[0] = 1 |
| K = -R[1]/R[0] |
| A[1] = K |
| Alpha = R[0] * (1-K**2] |
| |
| Do for i = 2 to M |
| |
| S = SUM ( R[j]*A[i-j] ,j=1,i-1 ) + R[i] |
| |
| K = -S / Alpha |
| |
| An[j] = A[j] + K*A[i-j] for j=1 to i-1 |
| where An[i] = new A[i] |
| An[i]=K |
| |
| Alpha=Alpha * (1-K**2) |
| |
| END |
| |
| Remarks on the dynamics of the calculations. |
| |
| The numbers used are in double precision in the following format : |
| A = AH <<16 + AL<<1. AH and AL are 16 bit signed integers. |
| Since the LSB's also contain a sign bit, this format does not |
| correspond to standard 32 bit integers. We use this format since |
| it allows fast execution of multiplications and divisions. |
| |
| "DPF" will refer to this special format in the following text. |
| See oper_32b.c |
| |
| The R[i] were normalized in routine AUTO (hence, R[i] < 1.0). |
| The K[i] and Alpha are theoretically < 1.0. |
| The A[i], for a sampling frequency of 8 kHz, are in practice |
| always inferior to 16.0. |
| |
| These characteristics allow straigthforward fixed-point |
| implementation. We choose to represent the parameters as |
| follows : |
| |
| R[i] Q31 +- .99.. |
| K[i] Q31 +- .99.. |
| Alpha Normalized -> mantissa in Q31 plus exponent |
| A[i] Q27 +- 15.999.. |
| |
| The additions are performed in 32 bit. For the summation used |
| to calculate the K[i], we multiply numbers in Q31 by numbers |
| in Q27, with the result of the multiplications in Q27, |
| resulting in a dynamic of +- 16. This is sufficient to avoid |
| overflow, since the final result of the summation is |
| necessarily < 1.0 as both the K[i] and Alpha are |
| theoretically < 1.0. |
|___________________________________________________________________________|
*/
/* Last A(z) for case of unstable filter */
void
Levinson (CodState *coder,
Word16 Rh[], /* (i) : Rh[M+1] Vector of autocorrelations (msb) */
Word16 Rl[], /* (i) : Rl[M+1] Vector of autocorrelations (lsb) */
Word16 A[], /* (o) Q12 : A[M] LPC coefficients (m = 10) */
Word16 rc[] /* (o) Q15 : rc[M] Reflection coefficients. */
)
{
Word16 i, j;
Word16 hi, lo;
Word16 Kh, Kl; /* reflection coefficient; hi and lo */
Word16 alp_h, alp_l, alp_exp; /* Prediction gain; hi lo and exponent */
Word16 Ah[M10 + 1], Al[M10 + 1]; /* LPC coef. in double prec. */
Word16 Anh[M10 + 1], Anl[M10 + 1]; /* LPC coef.for next iteration in double prec. */
Word32 t0, t1, t2; /* temporary variable */
/* K = A[1] = -R[1] / R[0] */
t1 = L_Comp (Rh[1], Rl[1]); /* R[1] in Q31 */
t2 = L_abs (t1); /* abs R[1] */
t0 = Div_32 (t2, Rh[0], Rl[0]); /* R[1]/R[0] in Q31 */
if (t1 > 0)
t0 = L_negate (t0); /* -R[1]/R[0] */
L_Extract (t0, &Kh, &Kl); /* K in DPF */
rc[0] = Kh;
t0 = L_shr (t0, 4); /* A[1] in Q27 */
L_Extract (t0, &Ah[1], &Al[1]); /* A[1] in DPF */
/* Alpha = R[0] * (1-K**2) */
t0 = Mpy_32 (Kh, Kl, Kh, Kl); /* K*K in Q31 */
t0 = L_abs (t0); /* Some case <0 !! */
t0 = L_sub ((Word32) 0x7fffffffL, t0); /* 1 - K*K in Q31 */
L_Extract (t0, &hi, &lo); /* DPF format */
t0 = Mpy_32 (Rh[0], Rl[0], hi, lo); /* Alpha in Q31 */
/* Normalize Alpha */
alp_exp = norm_l (t0);
t0 = L_shl (t0, alp_exp);
L_Extract (t0, &alp_h, &alp_l); /* DPF format */
/*--------------------------------------*
* ITERATIONS I=2 to M *
*--------------------------------------*/
for (i = 2; i <= M10; i++) {
/* t0 = SUM ( R[j]*A[i-j] ,j=1,i-1 ) + R[i] */
t0 = 0;
for (j = 1; j < i; j++)
t0 = L_add (t0, Mpy_32 (Rh[j], Rl[j], Ah[i - j], Al[i - j]));
t0 = L_shl (t0, 4); /* result in Q27 -> convert to Q31 */
/* No overflow possible */
t1 = L_Comp (Rh[i], Rl[i]);
t0 = L_add (t0, t1); /* add R[i] in Q31 */
/* K = -t0 / Alpha */
t1 = L_abs (t0);
t2 = Div_32 (t1, alp_h, alp_l); /* abs(t0)/Alpha */
if (t0 > 0)
t2 = L_negate (t2); /* K =-t0/Alpha */
t2 = L_shl (t2, alp_exp); /* denormalize; compare to Alpha */
L_Extract (t2, &Kh, &Kl); /* K in DPF */
rc[i - 1] = Kh;
/* Test for unstable filter. If unstable keep old A(z) */
if (sub (abs_s (Kh), 32750) > 0) {
for (j = 0; j <= M10; j++) {
A[j] = coder->old_A[j];
}
rc[0] = coder->old_rc[0]; /* only two rc coefficients are needed */
rc[1] = coder->old_rc[1];
return;
}
/*------------------------------------------*
* Compute new LPC coeff. -> An[i] *
* An[j]= A[j] + K*A[i-j] , j=1 to i-1 *
* An[i]= K *
*------------------------------------------*/
for (j = 1; j < i; j++) {
t0 = Mpy_32 (Kh, Kl, Ah[i - j], Al[i - j]);
t0 = L_add (t0, L_Comp (Ah[j], Al[j]));
L_Extract (t0, &Anh[j], &Anl[j]);
}
t2 = L_shr (t2, 4); /* t2 = K in Q31 ->convert to Q27 */
L_Extract (t2, &Anh[i], &Anl[i]); /* An[i] in Q27 */
/* Alpha = Alpha * (1-K**2) */
t0 = Mpy_32 (Kh, Kl, Kh, Kl); /* K*K in Q31 */
t0 = L_abs (t0); /* Some case <0 !! */
t0 = L_sub ((Word32) 0x7fffffffL, t0); /* 1 - K*K in Q31 */
L_Extract (t0, &hi, &lo); /* DPF format */
t0 = Mpy_32 (alp_h, alp_l, hi, lo); /* Alpha in Q31 */
/* Normalize Alpha */
j = norm_l (t0);
t0 = L_shl (t0, j);
L_Extract (t0, &alp_h, &alp_l); /* DPF format */
alp_exp = add (alp_exp, j); /* Add normalization to alp_exp */
/* A[j] = An[j] */
for (j = 1; j <= i; j++) {
Ah[j] = Anh[j];
Al[j] = Anl[j];
}
}
/* Truncate A[i] in Q27 to Q12 with rounding */
A[0] = 4096;
for (i = 1; i <= M10; i++) {
t0 = L_Comp (Ah[i], Al[i]);
coder->old_A[i] = A[i] = wround (L_shl (t0, 1));
}
coder->old_rc[0] = rc[0];
coder->old_rc[1] = rc[1];
return;
}
/*-------------------------------------------------------------*
* procedure Az_lsp: *
* ~~~~~~ *
* Compute the LSPs from the LPC coefficients (order=10) *
*-------------------------------------------------------------*/
Word16 Chebps_11 (Word16 x, Word16 f[], Word16 n);
Word16 Chebps_10 (Word16 x, Word16 f[], Word16 n);
void
Az_lsp (Word16 a[], /* (i) Q12 : predictor coefficients */
Word16 lsp[], /* (o) Q15 : line spectral pairs */
Word16 old_lsp[] /* (i) : old lsp[] (in case not found 10 roots) */
)
{
Flag Overflow;
Word16 i, j, nf, ip;
Word16 xlow, ylow, xhigh, yhigh, xmid, ymid, xint;
Word16 x, y, sign, exp;
Word16 *coef;
Word16 f1[M10 / 2 + 1], f2[M10 / 2 + 1];
Word32 t0, L_temp;
Flag ovf_coef;
Word16 (*pChebps) (Word16 x, Word16 f[], Word16 n);
/*-------------------------------------------------------------*
* find the sum and diff. pol. F1(z) and F2(z) *
* F1(z) <--- F1(z)/(1+z**-1) & F2(z) <--- F2(z)/(1-z**-1) *
* *
* f1[0] = 1.0; *
* f2[0] = 1.0; *
* *
* for (i = 0; i< NC; i++) *
* { *
* f1[i+1] = a[i+1] + a[M-i] - f1[i] ; *
* f2[i+1] = a[i+1] - a[M-i] + f2[i] ; *
* } *
*-------------------------------------------------------------*/
ovf_coef = 0;
pChebps = Chebps_11;
f1[0] = 2048; /* f1[0] = 1.0 is in Q11 */
f2[0] = 2048; /* f2[0] = 1.0 is in Q11 */
for (i = 0; i < NC; i++) {
Overflow = 0;
t0 = L_mult_o (a[i + 1], 16384, &Overflow); /* x = (a[i+1] + a[M-i]) >> 1 */
t0 = L_mac_o (t0, a[M10 - i], 16384, &Overflow); /* -> From Q12 to Q11 */
x = extract_h (t0);
if (Overflow) {
ovf_coef = 1;
}
Overflow = 0;
f1[i + 1] = sub_o (x, f1[i], &Overflow); /* f1[i+1] = a[i+1] + a[M-i] - f1[i] */
if (Overflow) {
ovf_coef = 1;
}
Overflow = 0;
t0 = L_mult_o (a[i + 1], 16384, &Overflow); /* x = (a[i+1] - a[M-i]) >> 1 */
t0 = L_msu_o (t0, a[M10 - i], 16384, &Overflow); /* -> From Q12 to Q11 */
x = extract_h (t0);
if (Overflow) {
ovf_coef = 1;
}
Overflow = 0;
f2[i + 1] = add_o (x, f2[i], &Overflow); /* f2[i+1] = a[i+1] - a[M-i] + f2[i] */
if (Overflow) {
ovf_coef = 1;
}
}
if (ovf_coef) {
/*printf("===== OVF ovf_coef =====\n"); */
pChebps = Chebps_10;
f1[0] = 1024; /* f1[0] = 1.0 is in Q10 */
f2[0] = 1024; /* f2[0] = 1.0 is in Q10 */
for (i = 0; i < NC; i++) {
t0 = L_mult (a[i + 1], 8192); /* x = (a[i+1] + a[M-i]) >> 1 */
t0 = L_mac (t0, a[M10 - i], 8192); /* -> From Q11 to Q10 */
x = extract_h (t0);
f1[i + 1] = sub (x, f1[i]); /* f1[i+1] = a[i+1] + a[M-i] - f1[i] */
t0 = L_mult (a[i + 1], 8192); /* x = (a[i+1] - a[M-i]) >> 1 */
t0 = L_msu (t0, a[M10 - i], 8192); /* -> From Q11 to Q10 */
x = extract_h (t0);
f2[i + 1] = add (x, f2[i]); /* f2[i+1] = a[i+1] - a[M-i] + f2[i] */
}
}
/*-------------------------------------------------------------*
* find the LSPs using the Chebichev pol. evaluation *
*-------------------------------------------------------------*/
nf = 0; /* number of found frequencies */
ip = 0; /* indicator for f1 or f2 */
coef = f1;
xlow = grid[0];
ylow = (*pChebps) (xlow, coef, NC);
j = 0;
while ((nf < M10) && (j < GRID_POINTS)) {
j = add (j, 1);
xhigh = xlow;
yhigh = ylow;
xlow = grid[j];
ylow = (*pChebps) (xlow, coef, NC);
L_temp = L_mult (ylow, yhigh);
if (L_temp <= (Word32) 0) {
/* divide 2 times the interval */
for (i = 0; i < 2; i++) {
xmid = add (shr (xlow, 1), shr (xhigh, 1)); /* xmid = (xlow + xhigh)/2 */
ymid = (*pChebps) (xmid, coef, NC);
L_temp = L_mult (ylow, ymid);
if (L_temp <= (Word32) 0) {
yhigh = ymid;
xhigh = xmid;
}
else {
ylow = ymid;
xlow = xmid;
}
}
/*-------------------------------------------------------------*
* Linear interpolation *
* xint = xlow - ylow*(xhigh-xlow)/(yhigh-ylow); *
*-------------------------------------------------------------*/
x = sub (xhigh, xlow);
y = sub (yhigh, ylow);
if (y == 0) {
xint = xlow;
}
else {
sign = y;
y = abs_s (y);
exp = norm_s (y);
y = shl (y, exp);
y = div_s ((Word16) 16383, y);
t0 = L_mult (x, y);
t0 = L_shr (t0, sub (20, exp));
y = extract_l (t0); /* y= (xhigh-xlow)/(yhigh-ylow) in Q11 */
if (sign < 0)
y = negate (y);
t0 = L_mult (ylow, y); /* result in Q26 */
t0 = L_shr (t0, 11); /* result in Q15 */
xint = sub (xlow, extract_l (t0)); /* xint = xlow - ylow*y */
}
lsp[nf] = xint;
xlow = xint;
nf = add (nf, 1);
if (ip == 0) {
ip = 1;
coef = f2;
}
else {
ip = 0;
coef = f1;
}
ylow = (*pChebps) (xlow, coef, NC);
}
}
/* Check if M roots found */
if (sub (nf, M10) < 0) {
for (i = 0; i < M10; i++) {
lsp[i] = old_lsp[i];
}
/* printf("\n !!Not 10 roots found in Az_lsp()!!!\n"); */
}
return;
}
/*--------------------------------------------------------------*
* function Chebps_11, Chebps_10: *
* ~~~~~~~~~~~~~~~~~~~~ *
* Evaluates the Chebichev polynomial series *
*--------------------------------------------------------------*
* *
* The polynomial order is *
* n = M/2 (M is the prediction order) *
* The polynomial is given by *
* C(x) = T_n(x) + f(1)T_n-1(x) + ... +f(n-1)T_1(x) + f(n)/2 *
* Arguments: *
* x: input value of evaluation; x = cos(frequency) in Q15 *
* f[]: coefficients of the pol. *
* in Q11(Chebps_11), in Q10(Chebps_10) *
* n: order of the pol. *
* *
* The value of C(x) is returned. (Saturated to +-1.99 in Q14) *
* *
*--------------------------------------------------------------*/
Word16
Chebps_11 (Word16 x, Word16 f[], Word16 n)
{
Word16 i, cheb;
Word16 b0_h, b0_l, b1_h, b1_l, b2_h, b2_l;
Word32 t0;
/* Note: All computation are done in Q24. */
b2_h = 256; /* b2 = 1.0 in Q24 DPF */
b2_l = 0;
t0 = L_mult (x, 512); /* 2*x in Q24 */
t0 = L_mac (t0, f[1], 4096); /* + f[1] in Q24 */
L_Extract (t0, &b1_h, &b1_l); /* b1 = 2*x + f[1] */
for (i = 2; i < n; i++) {
t0 = Mpy_32_16 (b1_h, b1_l, x); /* t0 = 2.0*x*b1 */
t0 = L_shl (t0, 1);
t0 = L_mac (t0, b2_h, (Word16) - 32768L); /* t0 = 2.0*x*b1 - b2 */
t0 = L_msu (t0, b2_l, 1);
t0 = L_mac (t0, f[i], 4096); /* t0 = 2.0*x*b1 - b2 + f[i]; */
L_Extract (t0, &b0_h, &b0_l); /* b0 = 2.0*x*b1 - b2 + f[i]; */
b2_l = b1_l; /* b2 = b1; */
b2_h = b1_h;
b1_l = b0_l; /* b1 = b0; */
b1_h = b0_h;
}
t0 = Mpy_32_16 (b1_h, b1_l, x); /* t0 = x*b1; */
t0 = L_mac (t0, b2_h, (Word16) - 32768L); /* t0 = x*b1 - b2 */
t0 = L_msu (t0, b2_l, 1);
t0 = L_mac (t0, f[i], 2048); /* t0 = x*b1 - b2 + f[i]/2 */
t0 = L_shl (t0, 6); /* Q24 to Q30 with saturation */
cheb = extract_h (t0); /* Result in Q14 */
return (cheb);
}
Word16
Chebps_10 (Word16 x, Word16 f[], Word16 n)
{
Word16 i, cheb;
Word16 b0_h, b0_l, b1_h, b1_l, b2_h, b2_l;
Word32 t0;
/* Note: All computation are done in Q23. */
b2_h = 128; /* b2 = 1.0 in Q23 DPF */
b2_l = 0;
t0 = L_mult (x, 256); /* 2*x in Q23 */
t0 = L_mac (t0, f[1], 4096); /* + f[1] in Q23 */
L_Extract (t0, &b1_h, &b1_l); /* b1 = 2*x + f[1] */
for (i = 2; i < n; i++) {
t0 = Mpy_32_16 (b1_h, b1_l, x); /* t0 = 2.0*x*b1 */
t0 = L_shl (t0, 1);
t0 = L_mac (t0, b2_h, (Word16) - 32768L); /* t0 = 2.0*x*b1 - b2 */
t0 = L_msu (t0, b2_l, 1);
t0 = L_mac (t0, f[i], 4096); /* t0 = 2.0*x*b1 - b2 + f[i]; */
L_Extract (t0, &b0_h, &b0_l); /* b0 = 2.0*x*b1 - b2 + f[i]; */
b2_l = b1_l; /* b2 = b1; */
b2_h = b1_h;
b1_l = b0_l; /* b1 = b0; */
b1_h = b0_h;
}
t0 = Mpy_32_16 (b1_h, b1_l, x); /* t0 = x*b1; */
t0 = L_mac (t0, b2_h, (Word16) - 32768L); /* t0 = x*b1 - b2 */
t0 = L_msu (t0, b2_l, 1);
t0 = L_mac (t0, f[i], 2048); /* t0 = x*b1 - b2 + f[i]/2 */
t0 = L_shl (t0, 7); /* Q23 to Q30 with saturation */
cheb = extract_h (t0); /* Result in Q14 */
return (cheb);
}