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AAC encoder: TNS fixes on short windows

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TNS was computing filter coefficients incorrectly for short windows
due to a few coefficient addressing bugs. Fixing them fixes lots of
instability with transients (short windows).
This commit is contained in:
Claudio Freire 2016-01-16 23:02:41 -03:00
parent df3fa48288
commit 3d0849cc90
1 changed files with 7 additions and 11 deletions
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18
libavcodec/aacenc_tns.c
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@ -178,23 +178,19 @@ void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce)
int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start];
const int sfb_len = sfb_end - sfb_start;
for (g = 0; g < sce->ics.num_swb; g++) {
if (w*16+g < sfb_start || w*16+g > sfb_end)
continue;
for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
if ((w+w2)*16+g > sfb_start + (sfb_len/2))
en[1] += band->energy;
else
en[0] += band->energy;
}
for (g = sfb_start; g < sce->ics.num_swb && g <= sfb_end; g++) {
FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[w*16+g];
if (g > sfb_start + (sfb_len/2))
en[1] += band->energy;
else
en[0] += band->energy;
}
if (coef_len <= 0 || sfb_len <= 0)
continue;
/* LPC */
gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[coef_start],
gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[w*128 + coef_start],
coef_len, order, coefs);
if (!order || gain < TNS_GAIN_THRESHOLD_LOW || gain > TNS_GAIN_THRESHOLD_HIGH)