/**
* Backward synthesis filter, find the LPC coefficients from past speech data.
*/
static void backward_filter(float *hist, float *rec, const float *window,
float *lpc, const float *tab,
int order, int n, int non_rec, int move_size)
{
float temp[MAX_BACKWARD_FILTER_ORDER+1];
do_hybrid_window(order, n, non_rec, temp, hist, rec, window);
if (!compute_lpc_coefs(temp, order, lpc, 0, 1, 1))
apply_window(lpc, lpc, tab, order);
memmove(hist, hist + n, move_size*sizeof(*hist));
}
/**
* Backward synthesis filter, find the LPC coefficients from past speech data.
*/
static void backward_filter(RA288Context *ractx,
float *hist, float *rec, const float *window,
float *lpc, const float *tab,
int order, int n, int non_rec, int move_size)
{
float temp[MAX_BACKWARD_FILTER_ORDER+1];
do_hybrid_window(ractx, order, n, non_rec, temp, hist, rec, window);
if (!compute_lpc_coefs(temp, order, lpc, 0, 1, 1))
ractx->fdsp->vector_fmul(lpc, lpc, tab, FFALIGN(order, 16));
memmove(hist, hist + n, move_size*sizeof(*hist));
}
/**
* Backward synthesis filter, find the LPC coefficients from past speech data.
*/
static void backward_filter(float *hist, float *rec, const float *window,
float *lpc, const float *tab,
int order, int n, int non_rec, int move_size)
{
#if __STDC_VERSION__ >= 199901L
float temp[order+1];
#else
float *temp = _alloca((order + 1) * sizeof(float));
#endif
do_hybrid_window(order, n, non_rec, temp, hist, rec, window);
if (!compute_lpc_coefs(temp, order, lpc, 0, 1, 1))
apply_window(lpc, lpc, tab, order);
memmove(hist, hist + n, move_size*sizeof(*hist));
}
/**
* Backward synthesis filter, find the LPC coefficients from past speech data.
*/
static void backward_filter(float *hist, float *rec, const float *window,
float *lpc, const float *tab,
int order, int n, int non_rec, int move_size)
{
#ifndef _MSC_VER
float temp[order+1];
#else
float *temp = av_malloc_items(order + 1, float);
#endif
do_hybrid_window(order, n, non_rec, temp, hist, rec, window);
if (!compute_lpc_coefs(temp, order, lpc, 0, 1, 1))
apply_window(lpc, lpc, tab, order);
memmove(hist, hist + n, move_size*sizeof(*hist));
#ifdef _MSC_VER
av_free(temp);
#endif
}
/* Apply TNS filter */
void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce)
{
TemporalNoiseShaping *tns = &sce->tns;
IndividualChannelStream *ics = &sce->ics;
int w, filt, m, i, top, order, bottom, start, end, size, inc;
const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
float lpc[TNS_MAX_ORDER];
for (w = 0; w < ics->num_windows; w++) {
bottom = ics->num_swb;
for (filt = 0; filt < tns->n_filt[w]; filt++) {
top = bottom;
bottom = FFMAX(0, top - tns->length[w][filt]);
order = tns->order[w][filt];
if (order == 0)
continue;
// tns_decode_coef
compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0);
start = ics->swb_offset[FFMIN(bottom, mmm)];
end = ics->swb_offset[FFMIN( top, mmm)];
if ((size = end - start) <= 0)
continue;
if (tns->direction[w][filt]) {
inc = -1;
start = end - 1;
} else {
inc = 1;
}
start += w * 128;
// ar filter
for (m = 0; m < size; m++, start += inc)
for (i = 1; i <= FFMIN(m, order); i++)
sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc];
}
}
}
