/*-----------------------------------------------------------*
* procedure Update_cng: *
* ~~~~~~~~~~ *
* Updates autocorrelation arrays *
* used for DTX/CNG *
* If Vad=1 : updating of array sumAcf *
*-----------------------------------------------------------*/
void Update_cng(
Word16 *r_h, /* (i) : MSB of frame autocorrelation */
Word16 exp_r, /* (i) : scaling factor associated */
Word16 Vad /* (i) : current Vad decision */
)
{
Word16 i;
Word16 *ptr1, *ptr2;
/* Update Acf and shAcf */
ptr1 = Acf + SIZ_ACF - 1;
ptr2 = ptr1 - MP1;
for(i=0; i<(SIZ_ACF-MP1); i++) {
*ptr1-- = *ptr2--;
}
for(i=NB_CURACF-1; i>=1; i--) {
sh_Acf[i] = sh_Acf[i-1];
}
/* Save current Acf */
sh_Acf[0] = negate(add(16, exp_r));
for(i=0; i<MP1; i++) {
Acf[i] = r_h[i];
}
fr_cur = add(fr_cur, 1);
if(sub(fr_cur, NB_CURACF) == 0) {
fr_cur = 0;
if(Vad != 0) {
Update_sumAcf();
}
}
return;
}
/*-----------------------------------------------------------*
* procedure Cod_cng: *
* ~~~~~~~~ *
* computes DTX decision *
* encodes SID frames *
* computes CNG excitation for encoder update *
*-----------------------------------------------------------*/
void Cod_cng(
DtxStatus *handle,
Word16 *exc, /* (i/o) : excitation array */
Word16 pastVad, /* (i) : previous VAD decision */
Word16 *lsp_old_q, /* (i/o) : previous quantized lsp */
Word16 *Aq, /* (o) : set of interpolated LPC coefficients */
Word16 *ana, /* (o) : coded SID parameters */
Word16 freq_prev[MA_NP][M],
/* (i/o) : previous LPS for quantization */
Word16 *seed /* (i/o) : random generator seed */
)
{
Word16 i;
Word16 curAcf[MP1];
Word16 bid[M], zero[MP1];
Word16 curCoeff[MP1];
Word16 lsp_new[M];
Word16 *lpcCoeff;
Word16 cur_igain;
Word16 energyq, temp;
/* Update Ener and sh_ener */
for(i = NB_GAIN-1; i>=1; i--) {
handle->ener[i] = handle->ener[i-1];
handle->sh_ener[i] = handle->sh_ener[i-1];
}
/* Compute current Acfs */
Calc_sum_acf(handle->Acf, handle->sh_Acf, curAcf, &(handle->sh_ener[0]), NB_CURACF);
/* Compute LPC coefficients and residual energy */
if(curAcf[0] == 0) {
handle->ener[0] = 0; /* should not happen */
}
else {
Set_zero(zero, MP1);
Levinson(handle, curAcf, zero, curCoeff, bid, &(handle->ener[0]));
}
/* if first frame of silence => SID frame */
if(pastVad != 0) {
ana[0] = 2;
handle->count_fr0 = 0;
handle->nb_ener = 1;
Qua_Sidgain(handle->ener, handle->sh_ener, handle->nb_ener, &energyq, &cur_igain);
}
else {
handle->nb_ener = add(handle->nb_ener, 1);
if(sub(handle->nb_ener, NB_GAIN) > 0) handle->nb_ener = NB_GAIN;
Qua_Sidgain(handle->ener, handle->sh_ener, handle->nb_ener, &energyq, &cur_igain);
/* Compute stationarity of current filter */
/* versus reference filter */
if(Cmp_filt(handle->RCoeff, handle->sh_RCoeff, curAcf, handle->ener[0], FRAC_THRESH1) != 0) {
handle->flag_chang = 1;
}
/* compare energy difference between current frame and last frame */
temp = abs_s(sub(handle->prev_energy, energyq));
temp = sub(temp, 2);
if (temp > 0) handle->flag_chang = 1;
handle->count_fr0 = add(handle->count_fr0, 1);
if(sub(handle->count_fr0, FR_SID_MIN) < 0) {
ana[0] = 0; /* no transmission */
}
else {
if(handle->flag_chang != 0) {
ana[0] = 2; /* transmit SID frame */
}
else{
ana[0] = 0;
}
handle->count_fr0 = FR_SID_MIN; /* to avoid overflow */
}
}
if(sub(ana[0], 2) == 0) {
/* Reset frame count and change flag */
handle->count_fr0 = 0;
handle->flag_chang = 0;
/* Compute past average filter */
Calc_pastfilt(handle, handle->pastCoeff);
Calc_RCoeff(handle->pastCoeff, handle->RCoeff, &(handle->sh_RCoeff));
/* Compute stationarity of current filter */
/* versus past average filter */
/* if stationary */
/* transmit average filter => new ref. filter */
if(Cmp_filt(handle->RCoeff, handle->sh_RCoeff, curAcf, handle->ener[0], FRAC_THRESH2) == 0) {
lpcCoeff = handle->pastCoeff;
}
/* else */
/* transmit current filter => new ref. filter */
else {
lpcCoeff = curCoeff;
Calc_RCoeff(curCoeff, handle->RCoeff, &(handle->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, handle->lspSid_q, freq_prev, &ana[1]);
handle->prev_energy = energyq;
ana[4] = cur_igain;
handle->sid_gain = tab_Sidgain[cur_igain];
} /* end of SID frame case */
/* Compute new excitation */
if(pastVad != 0) {
handle->cur_gain = handle->sid_gain;
}
else {
handle->cur_gain = mult_r(handle->cur_gain, A_GAIN0);
handle->cur_gain = add(handle->cur_gain, mult_r(handle->sid_gain, A_GAIN1));
}
Calc_exc_rand(handle->L_exc_err, handle->cur_gain, exc, seed, FLAG_COD);
Int_qlpc(lsp_old_q, handle->lspSid_q, Aq);
for(i=0; i<M; i++) {
lsp_old_q[i] = handle->lspSid_q[i];
}
/* Update sumAcf if fr_cur = 0 */
if(handle->fr_cur == 0) {
Update_sumAcf(handle);
}
return;
}