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Member "ffmpeg-4.0.1/libavcodec/aacenc_is.c" (13 Apr 2018, 7385 Bytes) of package /linux/misc/ffmpeg-4.0.1.tar.xz:


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    1 /*
    2  * AAC encoder intensity stereo
    3  * Copyright (C) 2015 Rostislav Pehlivanov
    4  *
    5  * This file is part of FFmpeg.
    6  *
    7  * FFmpeg is free software; you can redistribute it and/or
    8  * modify it under the terms of the GNU Lesser General Public
    9  * License as published by the Free Software Foundation; either
   10  * version 2.1 of the License, or (at your option) any later version.
   11  *
   12  * FFmpeg is distributed in the hope that it will be useful,
   13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   15  * Lesser General Public License for more details.
   16  *
   17  * You should have received a copy of the GNU Lesser General Public
   18  * License along with FFmpeg; if not, write to the Free Software
   19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   20  */
   21 
   22 /**
   23  * @file
   24  * AAC encoder Intensity Stereo
   25  * @author Rostislav Pehlivanov ( atomnuker gmail com )
   26  */
   27 
   28 #include "aacenc.h"
   29 #include "aacenc_utils.h"
   30 #include "aacenc_is.h"
   31 #include "aacenc_quantization.h"
   32 
   33 struct AACISError ff_aac_is_encoding_err(AACEncContext *s, ChannelElement *cpe,
   34                                          int start, int w, int g, float ener0,
   35                                          float ener1, float ener01,
   36                                          int use_pcoeffs, int phase)
   37 {
   38     int i, w2;
   39     SingleChannelElement *sce0 = &cpe->ch[0];
   40     SingleChannelElement *sce1 = &cpe->ch[1];
   41     float *L = use_pcoeffs ? sce0->pcoeffs : sce0->coeffs;
   42     float *R = use_pcoeffs ? sce1->pcoeffs : sce1->coeffs;
   43     float *L34 = &s->scoefs[256*0], *R34 = &s->scoefs[256*1];
   44     float *IS  = &s->scoefs[256*2], *I34 = &s->scoefs[256*3];
   45     float dist1 = 0.0f, dist2 = 0.0f;
   46     struct AACISError is_error = {0};
   47 
   48     if (ener01 <= 0 || ener0 <= 0) {
   49         is_error.pass = 0;
   50         return is_error;
   51     }
   52 
   53     for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
   54         FFPsyBand *band0 = &s->psy.ch[s->cur_channel+0].psy_bands[(w+w2)*16+g];
   55         FFPsyBand *band1 = &s->psy.ch[s->cur_channel+1].psy_bands[(w+w2)*16+g];
   56         int is_band_type, is_sf_idx = FFMAX(1, sce0->sf_idx[w*16+g]-4);
   57         float e01_34 = phase*pos_pow34(ener1/ener0);
   58         float maxval, dist_spec_err = 0.0f;
   59         float minthr = FFMIN(band0->threshold, band1->threshold);
   60         for (i = 0; i < sce0->ics.swb_sizes[g]; i++)
   61             IS[i] = (L[start+(w+w2)*128+i] + phase*R[start+(w+w2)*128+i])*sqrt(ener0/ener01);
   62         s->abs_pow34(L34, &L[start+(w+w2)*128], sce0->ics.swb_sizes[g]);
   63         s->abs_pow34(R34, &R[start+(w+w2)*128], sce0->ics.swb_sizes[g]);
   64         s->abs_pow34(I34, IS,                   sce0->ics.swb_sizes[g]);
   65         maxval = find_max_val(1, sce0->ics.swb_sizes[g], I34);
   66         is_band_type = find_min_book(maxval, is_sf_idx);
   67         dist1 += quantize_band_cost(s, &L[start + (w+w2)*128], L34,
   68                                     sce0->ics.swb_sizes[g],
   69                                     sce0->sf_idx[w*16+g],
   70                                     sce0->band_type[w*16+g],
   71                                     s->lambda / band0->threshold, INFINITY, NULL, NULL, 0);
   72         dist1 += quantize_band_cost(s, &R[start + (w+w2)*128], R34,
   73                                     sce1->ics.swb_sizes[g],
   74                                     sce1->sf_idx[w*16+g],
   75                                     sce1->band_type[w*16+g],
   76                                     s->lambda / band1->threshold, INFINITY, NULL, NULL, 0);
   77         dist2 += quantize_band_cost(s, IS, I34, sce0->ics.swb_sizes[g],
   78                                     is_sf_idx, is_band_type,
   79                                     s->lambda / minthr, INFINITY, NULL, NULL, 0);
   80         for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
   81             dist_spec_err += (L34[i] - I34[i])*(L34[i] - I34[i]);
   82             dist_spec_err += (R34[i] - I34[i]*e01_34)*(R34[i] - I34[i]*e01_34);
   83         }
   84         dist_spec_err *= s->lambda / minthr;
   85         dist2 += dist_spec_err;
   86     }
   87 
   88     is_error.pass = dist2 <= dist1;
   89     is_error.phase = phase;
   90     is_error.error = dist2 - dist1;
   91     is_error.dist1 = dist1;
   92     is_error.dist2 = dist2;
   93     is_error.ener01 = ener01;
   94 
   95     return is_error;
   96 }
   97 
   98 void ff_aac_search_for_is(AACEncContext *s, AVCodecContext *avctx, ChannelElement *cpe)
   99 {
  100     SingleChannelElement *sce0 = &cpe->ch[0];
  101     SingleChannelElement *sce1 = &cpe->ch[1];
  102     int start = 0, count = 0, w, w2, g, i, prev_sf1 = -1, prev_bt = -1, prev_is = 0;
  103     const float freq_mult = avctx->sample_rate/(1024.0f/sce0->ics.num_windows)/2.0f;
  104     uint8_t nextband1[128];
  105 
  106     if (!cpe->common_window)
  107         return;
  108 
  109     /** Scout out next nonzero bands */
  110     ff_init_nextband_map(sce1, nextband1);
  111 
  112     for (w = 0; w < sce0->ics.num_windows; w += sce0->ics.group_len[w]) {
  113         start = 0;
  114         for (g = 0;  g < sce0->ics.num_swb; g++) {
  115             if (start*freq_mult > INT_STEREO_LOW_LIMIT*(s->lambda/170.0f) &&
  116                 cpe->ch[0].band_type[w*16+g] != NOISE_BT && !cpe->ch[0].zeroes[w*16+g] &&
  117                 cpe->ch[1].band_type[w*16+g] != NOISE_BT && !cpe->ch[1].zeroes[w*16+g] &&
  118                 ff_sfdelta_can_remove_band(sce1, nextband1, prev_sf1, w*16+g)) {
  119                 float ener0 = 0.0f, ener1 = 0.0f, ener01 = 0.0f, ener01p = 0.0f;
  120                 struct AACISError ph_err1, ph_err2, *best;
  121                 for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
  122                     for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
  123                         float coef0 = sce0->coeffs[start+(w+w2)*128+i];
  124                         float coef1 = sce1->coeffs[start+(w+w2)*128+i];
  125                         ener0  += coef0*coef0;
  126                         ener1  += coef1*coef1;
  127                         ener01 += (coef0 + coef1)*(coef0 + coef1);
  128                         ener01p += (coef0 - coef1)*(coef0 - coef1);
  129                     }
  130                 }
  131                 ph_err1 = ff_aac_is_encoding_err(s, cpe, start, w, g,
  132                                                  ener0, ener1, ener01p, 0, -1);
  133                 ph_err2 = ff_aac_is_encoding_err(s, cpe, start, w, g,
  134                                                  ener0, ener1, ener01, 0, +1);
  135                 best = (ph_err1.pass && ph_err1.error < ph_err2.error) ? &ph_err1 : &ph_err2;
  136                 if (best->pass) {
  137                     cpe->is_mask[w*16+g] = 1;
  138                     cpe->ms_mask[w*16+g] = 0;
  139                     cpe->ch[0].is_ener[w*16+g] = sqrt(ener0 / best->ener01);
  140                     cpe->ch[1].is_ener[w*16+g] = ener0/ener1;
  141                     cpe->ch[1].band_type[w*16+g] = (best->phase > 0) ? INTENSITY_BT : INTENSITY_BT2;
  142                     if (prev_is && prev_bt != cpe->ch[1].band_type[w*16+g]) {
  143                         /** Flip M/S mask and pick the other CB, since it encodes more efficiently */
  144                         cpe->ms_mask[w*16+g] = 1;
  145                         cpe->ch[1].band_type[w*16+g] = (best->phase > 0) ? INTENSITY_BT2 : INTENSITY_BT;
  146                     }
  147                     prev_bt = cpe->ch[1].band_type[w*16+g];
  148                     count++;
  149                 }
  150             }
  151             if (!sce1->zeroes[w*16+g] && sce1->band_type[w*16+g] < RESERVED_BT)
  152                 prev_sf1 = sce1->sf_idx[w*16+g];
  153             prev_is = cpe->is_mask[w*16+g];
  154             start += sce0->ics.swb_sizes[g];
  155         }
  156     }
  157     cpe->is_mode = !!count;
  158 }