www.pudn.com > g729_audio_encode.rar > dtx.c
/*
ITU-T G.729 Annex B ANSI-C Source Code
Version 1.3 Last modified: August 1997
Copyright (c) 1996, France Telecom, Rockwell International,
Universite de Sherbrooke.
All rights reserved.
*/
/* DTX and Comfort Noise Generator - Encoder part */
#include
#include
#include "typedef.h"
#include "basic_op.h"
#include "ld8k.h"
#include "oper_32b.h"
#include "tab_ld8k.h"
#include "vad.h"
#include "dtx.h"
#include "tab_dtx.h"
#include "sid.h"
/* Static Variables */
static Word16 lspSid_q[M] ;
static Word16 pastCoeff[MP1];
static Word16 RCoeff[MP1];
static Word16 sh_RCoeff;
static Word16 Acf[SIZ_ACF];
static Word16 sh_Acf[NB_CURACF];
static Word16 sumAcf[SIZ_SUMACF];
static Word16 sh_sumAcf[NB_SUMACF];
static Word16 ener[NB_GAIN];
static Word16 sh_ener[NB_GAIN];
static Word16 fr_cur;
static Word16 cur_gain;
static Word16 nb_ener;
static Word16 sid_gain;
static Word16 flag_chang;
static Word16 prev_energy;
static Word16 count_fr0;
/* Local functions */
static void Calc_pastfilt(Word16 *Coeff);
static void Calc_RCoeff(Word16 *Coeff, Word16 *RCoeff, Word16 *sh_RCoeff);
static Word16 Cmp_filt(Word16 *RCoeff, Word16 sh_RCoeff, Word16 *acf,
Word16 alpha, Word16 Fracthresh);
static void Calc_sum_acf(Word16 *acf, Word16 *sh_acf,
Word16 *sum, Word16 *sh_sum, Word16 nb);
static void Update_sumAcf(void);
/*-----------------------------------------------------------*
* procedure Init_Cod_cng: *
* ~~~~~~~~~~~~ *
* Initialize variables used for dtx at the encoder *
*-----------------------------------------------------------*/
void Init_Cod_cng(void)
{
Word16 i;
for(i=0; i=1; i--) {
ener[i] = ener[i-1];
sh_ener[i] = sh_ener[i-1];
}
/* Compute current Acfs */
Calc_sum_acf(Acf, sh_Acf, curAcf, &sh_ener[0], NB_CURACF);
/* Compute LPC coefficients and residual energy */
if(curAcf[0] == 0) {
ener[0] = 0; /* should not happen */
}
else {
Set_zero(zero, MP1);
Levinson(curAcf, zero, curCoeff, bid, &ener[0]);
}
/* if first frame of silence => SID frame */
if(pastVad != 0) {
ana[0] = 2;
count_fr0 = 0;
nb_ener = 1;
Qua_Sidgain(ener, sh_ener, nb_ener, &energyq, &cur_igain);
}
else {
nb_ener = add(nb_ener, 1);
if(sub(nb_ener, NB_GAIN) > 0) nb_ener = NB_GAIN;
Qua_Sidgain(ener, sh_ener, nb_ener, &energyq, &cur_igain);
/* Compute stationarity of current filter */
/* versus reference filter */
if(Cmp_filt(RCoeff, sh_RCoeff, curAcf, ener[0], FRAC_THRESH1) != 0) {
flag_chang = 1;
}
/* compare energy difference between current frame and last frame */
temp = abs_s(sub(prev_energy, energyq));
temp = sub(temp, 2);
if (temp > 0) flag_chang = 1;
count_fr0 = add(count_fr0, 1);
if(sub(count_fr0, FR_SID_MIN) < 0) {
ana[0] = 0; /* no transmission */
}
else {
if(flag_chang != 0) {
ana[0] = 2; /* transmit SID frame */
}
else{
ana[0] = 0;
}
count_fr0 = FR_SID_MIN; /* to avoid overflow */
}
}
if(sub(ana[0], 2) == 0) {
/* Reset frame count and change flag */
count_fr0 = 0;
flag_chang = 0;
/* Compute past average filter */
Calc_pastfilt(pastCoeff);
Calc_RCoeff(pastCoeff, RCoeff, &sh_RCoeff);
/* Compute stationarity of current filter */
/* versus past average filter */
/* if stationary */
/* transmit average filter => new ref. filter */
if(Cmp_filt(RCoeff, sh_RCoeff, curAcf, ener[0], FRAC_THRESH2) == 0) {
lpcCoeff = pastCoeff;
}
/* else */
/* transmit current filter => new ref. filter */
else {
lpcCoeff = curCoeff;
Calc_RCoeff(curCoeff, RCoeff, &sh_RCoeff);
}
/* Compute SID frame codes */
Az_lsp(lpcCoeff, lsp_new, lsp_old_q); /* From A(z) to lsp */
/* LSP quantization */
lsfq_noise(lsp_new, lspSid_q, freq_prev, &ana[1]);
prev_energy = energyq;
ana[4] = cur_igain;
sid_gain = tab_Sidgain[cur_igain];
} /* end of SID frame case */
/* Compute new excitation */
if(pastVad != 0) {
cur_gain = sid_gain;
}
else {
cur_gain = mult_r(cur_gain, A_GAIN0);
cur_gain = add(cur_gain, mult_r(sid_gain, A_GAIN1));
}
Calc_exc_rand(cur_gain, exc, seed, FLAG_COD);
Int_qlpc(lsp_old_q, lspSid_q, Aq);
for(i=0; i=1; i--) {
sh_Acf[i] = sh_Acf[i-1];
}
/* Save current Acf */
sh_Acf[0] = negate(add(16, exp_r));
for(i=0; iM) Coeff[j] ** 2 */
L_acc = 0L;
for(j=0; j <= M; j++) {
L_acc = L_mac(L_acc, Coeff[j], Coeff[j]);
}
/* Compute exponent RCoeff */
sh1 = norm_l(L_acc);
L_acc = L_shl(L_acc, sh1);
RCoeff[0] = round(L_acc);
/* RCoeff[i] = SUM(j=0->M-i) Coeff[j] * Coeff[j+i] */
for(i=1; i<=M; i++) {
L_acc = 0L;
for(j=0; j<=M-i; j++) {
L_acc = L_mac(L_acc, Coeff[j], Coeff[j+i]);
}
L_acc = L_shl(L_acc, sh1);
RCoeff[i] = round(L_acc);
}
*sh_RCoeff = sh1;
return;
}
/* Compute Itakura distance and compare to threshold */
/*****************************************************/
static Word16 Cmp_filt(Word16 *RCoeff, Word16 sh_RCoeff, Word16 *acf,
Word16 alpha, Word16 FracThresh)
{
Word32 L_temp0, L_temp1;
Word16 temp1, temp2, sh[2], ind;
Word16 i;
Word16 diff, flag;
extern Flag Overflow;
sh[0] = 0;
sh[1] = 0;
ind = 1;
flag = 0;
do {
Overflow = 0;
temp1 = shr(RCoeff[0], sh[0]);
temp2 = shr(acf[0], sh[1]);
L_temp0 = L_shr(L_mult(temp1, temp2),1);
for(i=1; i <= M; i++) {
temp1 = shr(RCoeff[i], sh[0]);
temp2 = shr(acf[i], sh[1]);
L_temp0 = L_mac(L_temp0, temp1, temp2);
}
if(Overflow != 0) {
sh[(int)ind] = add(sh[(int)ind], 1);
ind = sub(1, ind);
}
else flag = 1;
} while (flag == 0);
temp1 = mult_r(alpha, FracThresh);
L_temp1 = L_add(L_deposit_l(temp1), L_deposit_l(alpha));
temp1 = add(sh_RCoeff, 9); /* 9 = Lpc_justif. * 2 - 16 + 1 */
temp2 = add(sh[0], sh[1]);
temp1 = sub(temp1, temp2);
L_temp1 = L_shl(L_temp1, temp1);
L_temp0 = L_sub(L_temp0, L_temp1);
if(L_temp0 > 0L) diff = 1;
else diff = 0;
return(diff);
}
/* Compute past average filter */
/*******************************/
static void Calc_pastfilt(Word16 *Coeff)
{
Word16 i;
Word16 s_sumAcf[MP1];
Word16 bid[M], zero[MP1];
Word16 temp;
Calc_sum_acf(sumAcf, sh_sumAcf, s_sumAcf, &temp, NB_SUMACF);
if(s_sumAcf[0] == 0L) {
Coeff[0] = 4096;
for(i=1; i<=M; i++) Coeff[i] = 0;
return;
}
Set_zero(zero, MP1);
Levinson(s_sumAcf, zero, Coeff, bid, &temp);
return;
}
/* Update sumAcf */
/*****************/
static void Update_sumAcf(void)
{
Word16 *ptr1, *ptr2;
Word16 i;
/*** Move sumAcf ***/
ptr1 = sumAcf + SIZ_SUMACF - 1;
ptr2 = ptr1 - MP1;
for(i=0; i<(SIZ_SUMACF-MP1); i++) {
*ptr1-- = *ptr2--;
}
for(i=NB_SUMACF-1; i>=1; i--) {
sh_sumAcf[i] = sh_sumAcf[i-1];
}
/* Compute new sumAcf */
Calc_sum_acf(Acf, sh_Acf, sumAcf, sh_sumAcf, NB_CURACF);
return;
}
/* Compute sum of acfs (curAcf, sumAcf or s_sumAcf) */
/****************************************************/
static void Calc_sum_acf(Word16 *acf, Word16 *sh_acf,
Word16 *sum, Word16 *sh_sum, Word16 nb)
{
Word16 *ptr1;
Word32 L_temp, L_tab[MP1];
Word16 sh0, temp;
Word16 i, j;
/* Compute sum = sum of nb acfs */
/* Find sh_acf minimum */
sh0 = sh_acf[0];
for(i=1; i