forked from KolibriOS/kolibrios
195 lines
7.3 KiB
C
195 lines
7.3 KiB
C
/*
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* AAC encoder TNS
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* Copyright (C) 2015 Rostislav Pehlivanov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* AAC encoder temporal noise shaping
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* @author Rostislav Pehlivanov ( atomnuker gmail com )
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*/
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#include "aacenc.h"
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#include "aacenc_tns.h"
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#include "aactab.h"
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#include "aacenc_utils.h"
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#include "aacenc_quantization.h"
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/**
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* Encode TNS data.
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* Coefficient compression saves a single bit per coefficient.
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*/
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void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce)
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{
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uint8_t u_coef;
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const uint8_t coef_res = TNS_Q_BITS == 4;
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int i, w, filt, coef_len, coef_compress = 0;
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const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
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TemporalNoiseShaping *tns = &sce->tns;
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if (!sce->tns.present)
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return;
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for (i = 0; i < sce->ics.num_windows; i++) {
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put_bits(&s->pb, 2 - is8, sce->tns.n_filt[i]);
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if (tns->n_filt[i]) {
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put_bits(&s->pb, 1, coef_res);
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for (filt = 0; filt < tns->n_filt[i]; filt++) {
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put_bits(&s->pb, 6 - 2 * is8, tns->length[i][filt]);
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put_bits(&s->pb, 5 - 2 * is8, tns->order[i][filt]);
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if (tns->order[i][filt]) {
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put_bits(&s->pb, 1, !!tns->direction[i][filt]);
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put_bits(&s->pb, 1, !!coef_compress);
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coef_len = coef_res + 3 - coef_compress;
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for (w = 0; w < tns->order[i][filt]; w++) {
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u_coef = (tns->coef_idx[i][filt][w])&(~(~0<<coef_len));
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put_bits(&s->pb, coef_len, u_coef);
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}
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}
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}
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}
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}
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}
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static inline void quantize_coefs(double *coef, int *idx, float *lpc, int order)
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{
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int i;
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uint8_t u_coef;
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const float *quant_arr = tns_tmp2_map[TNS_Q_BITS == 4];
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const double iqfac_p = ((1 << (TNS_Q_BITS-1)) - 0.5)/(M_PI/2.0);
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const double iqfac_m = ((1 << (TNS_Q_BITS-1)) + 0.5)/(M_PI/2.0);
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for (i = 0; i < order; i++) {
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idx[i] = ceilf(asin(coef[i])*((coef[i] >= 0) ? iqfac_p : iqfac_m));
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u_coef = (idx[i])&(~(~0<<TNS_Q_BITS));
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lpc[i] = quant_arr[u_coef];
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}
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}
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/* Apply TNS filter */
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void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce)
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{
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TemporalNoiseShaping *tns = &sce->tns;
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IndividualChannelStream *ics = &sce->ics;
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int w, filt, m, i, top, order, bottom, start, end, size, inc;
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const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
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float lpc[TNS_MAX_ORDER];
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for (w = 0; w < ics->num_windows; w++) {
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bottom = ics->num_swb;
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for (filt = 0; filt < tns->n_filt[w]; filt++) {
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top = bottom;
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bottom = FFMAX(0, top - tns->length[w][filt]);
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order = tns->order[w][filt];
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if (order == 0)
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continue;
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// tns_decode_coef
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compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0);
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start = ics->swb_offset[FFMIN(bottom, mmm)];
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end = ics->swb_offset[FFMIN( top, mmm)];
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if ((size = end - start) <= 0)
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continue;
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if (tns->direction[w][filt]) {
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inc = -1;
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start = end - 1;
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} else {
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inc = 1;
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}
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start += w * 128;
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// ar filter
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for (m = 0; m < size; m++, start += inc)
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for (i = 1; i <= FFMIN(m, order); i++)
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sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc];
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}
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}
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}
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void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce)
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{
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TemporalNoiseShaping *tns = &sce->tns;
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int w, w2, g, count = 0;
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const int mmm = FFMIN(sce->ics.tns_max_bands, sce->ics.max_sfb);
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const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
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const int order = is8 ? 7 : s->profile == FF_PROFILE_AAC_LOW ? 12 : TNS_MAX_ORDER;
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int sfb_start = av_clip(tns_min_sfb[is8][s->samplerate_index], 0, mmm);
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int sfb_end = av_clip(sce->ics.num_swb, 0, mmm);
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for (w = 0; w < sce->ics.num_windows; w++) {
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float e_ratio = 0.0f, threshold = 0.0f, spread = 0.0f, en[2] = {0.0, 0.0f};
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double gain = 0.0f, coefs[MAX_LPC_ORDER] = {0};
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int coef_start = w*sce->ics.num_swb + sce->ics.swb_offset[sfb_start];
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int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start];
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for (g = 0; g < sce->ics.num_swb; g++) {
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if (w*16+g < sfb_start || w*16+g > sfb_end)
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continue;
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for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
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FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
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if ((w+w2)*16+g > sfb_start + ((sfb_end - sfb_start)/2))
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en[1] += band->energy;
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else
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en[0] += band->energy;
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threshold += band->threshold;
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spread += band->spread;
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}
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}
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if (coef_len <= 0 || (sfb_end - sfb_start) <= 0)
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continue;
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else
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e_ratio = en[0]/en[1];
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/* LPC */
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gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[coef_start],
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coef_len, order, coefs);
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if (gain > TNS_GAIN_THRESHOLD_LOW && gain < TNS_GAIN_THRESHOLD_HIGH &&
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(en[0]+en[1]) > TNS_GAIN_THRESHOLD_LOW*threshold &&
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spread < TNS_SPREAD_THRESHOLD && order) {
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if (is8 || order < 2 || (e_ratio > TNS_E_RATIO_LOW && e_ratio < TNS_E_RATIO_HIGH)) {
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tns->n_filt[w] = 1;
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for (g = 0; g < tns->n_filt[w]; g++) {
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tns->length[w][g] = sfb_end - sfb_start;
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tns->direction[w][g] = en[0] < en[1];
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tns->order[w][g] = order;
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quantize_coefs(coefs, tns->coef_idx[w][g], tns->coef[w][g],
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order);
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}
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} else { /* 2 filters due to energy disbalance */
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tns->n_filt[w] = 2;
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for (g = 0; g < tns->n_filt[w]; g++) {
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tns->direction[w][g] = en[g] < en[!g];
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tns->order[w][g] = !g ? order/2 : order - tns->order[w][g-1];
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tns->length[w][g] = !g ? (sfb_end - sfb_start)/2 : \
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(sfb_end - sfb_start) - tns->length[w][g-1];
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quantize_coefs(&coefs[!g ? 0 : order - tns->order[w][g-1]],
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tns->coef_idx[w][g], tns->coef[w][g],
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tns->order[w][g]);
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}
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}
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count++;
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}
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}
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sce->tns.present = !!count;
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}
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