/*-----------------------------------------------------------*
* procedure dec_cng: *
* ~~~~~~~~ *
* Receives frame type *
* 0 : for untransmitted frames *
* 2 : for SID frames *
* Decodes SID frames *
* Computes current frame excitation *
* Computes current frame LSPs
*-----------------------------------------------------------*/
void dec_cng(
int past_ftyp, /* (i) : past frame type */
FLOAT sid_sav, /* (i) : energy to recover SID gain */
int *parm, /* (i) : coded SID parameters */
FLOAT *exc, /* (i/o) : excitation array */
FLOAT *lsp_old, /* (i/o) : previous lsp */
FLOAT *A_t, /* (o) : set of interpolated LPC coefficients */
INT16 *seed, /* (i/o) : random generator seed */
FLOAT freq_prev[MA_NP][M] /* (i/o) : previous LPS for quantization */
)
{
FLOAT temp;
int ind;
/* SID Frame */
/*************/
if(parm[0] != 0) {
sid_gain = tab_Sidgain[parm[4]];
/* Inverse quantization of the LSP */
sid_lsfq_decode(&parm[1], lspSid, freq_prev);
}
/* non SID Frame */
/*****************/
else {
/* Case of 1st SID frame erased : quantize-decode */
/* energy estimate stored in sid_gain */
if(past_ftyp > 1) {
qua_Sidgain(&sid_sav, 0, &temp, &ind);
sid_gain = tab_Sidgain[ind];
}
}
if(past_ftyp > 1) {
cur_gain = sid_gain;
}
else {
cur_gain *= A_GAIN0;
cur_gain += A_GAIN1 * sid_gain;
}
calc_exc_rand(cur_gain, exc, seed, FLAG_DEC);
/* Interpolate the Lsp vectors */
int_qlpc(lsp_old, lspSid, A_t);
copy(lspSid, lsp_old, M);
return;
}
/*-----------------------------------------------------------*
* procedure cod_cng: *
* ~~~~~~~~ *
* computes DTX decision *
* encodes SID frames *
* computes CNG excitation for encoder update *
*-----------------------------------------------------------*/
void cod_cng(float * exc, /* (i/o) : excitation array */
int pastVad, /* (i) : previous VAD decision */
float * lsp_old_q, /* (i/o) : previous quantized lsp */
float * old_A, /* (i/o) : last stable filter LPC coefficients */
float * old_rc, /* (i/o) : last stable filter Reflection coefficients. */
float * Aq, /* (o) : set of interpolated LPC coefficients */
int *ana, /* (o) : coded SID parameters */
float freq_prev[MA_NP][M], /* (i/o) : previous LPS for quantization */
int16_t * seed /* (i/o) : random generator seed */
)
{
int i;
float curAcf[MP1];
float bid[MP1];
float curCoeff[MP1];
float lsp_new[M];
float *lpcCoeff;
int cur_igain;
float energyq;
/* Update Ener */
for (i = NB_GAIN - 1; i >= 1; i--) {
ener[i] = ener[i - 1];
}
/* Compute current Acfs */
calc_sum_acf(Acf, curAcf, NB_CURACF);
/* Compute LPC coefficients and residual energy */
if (curAcf[0] == (float) 0.) {
ener[0] = (float) 0.; /* should not happen */
} else {
ener[0] = levinsone(M, curAcf, curCoeff, bid, old_A, old_rc);
}
/* if first frame of silence => SID frame */
if (pastVad != 0) {
ana[0] = 1;
count_fr0 = 0;
nb_ener = 1;
qua_Sidgain(ener, nb_ener, &energyq, &cur_igain);
} else {
nb_ener++;
if (nb_ener > NB_GAIN)
nb_ener = NB_GAIN;
qua_Sidgain(ener, nb_ener, &energyq, &cur_igain);
/* Compute stationarity of current filter */
/* versus reference filter */
if (cmp_filt(RCoeff, curAcf, ener[0], THRESH1) != 0) {
flag_chang = 1;
}
/* compare energy difference between current frame and last frame */
if ((float) fabs(prev_energy - energyq) > (float) 2.0)
flag_chang = 1;
count_fr0++;
if (count_fr0 < FR_SID_MIN) {
ana[0] = 0; /* no transmission */
} else {
if (flag_chang != 0) {
ana[0] = 1; /* transmit SID frame */
} else {
ana[0] = 0;
}
count_fr0 = FR_SID_MIN; /* to avoid overflow */
}
}
if (ana[0] == 1) {
/* Reset frame count and change flag */
count_fr0 = 0;
flag_chang = 0;
/* Compute past average filter */
calc_pastfilt(pastCoeff, old_A, old_rc);
calc_RCoeff(pastCoeff, RCoeff);
/* Compute stationarity of current filter */
/* versus past average filter */
/* if stationary */
/* transmit average filter => new ref. filter */
if (cmp_filt(RCoeff, curAcf, ener[0], THRESH2) == 0) {
lpcCoeff = pastCoeff;
}
/* else */
/* transmit current filter => new ref. filter */
else {
lpcCoeff = curCoeff;
calc_RCoeff(curCoeff, 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 *= A_GAIN0;
cur_gain += A_GAIN1 * sid_gain;
}
calc_exc_rand(cur_gain, exc, seed, FLAG_COD);
int_qlpc(lsp_old_q, lspSid_q, Aq);
for (i = 0; i < M; i++) {
lsp_old_q[i] = lspSid_q[i];
}
/* Update sumAcf if fr_cur = 0 */
if (fr_cur == 0) {
update_sumAcf();
}
return;
}
