"Fossies" - the Fresh Open Source Software Archive

Member "ffmpeg-4.0.1/libavcodec/aacenc_ltp.c" (13 Apr 2018, 8476 Bytes) of package /linux/misc/ffmpeg-4.0.1.tar.xz:


As a special service "Fossies" has tried to format the requested source page into HTML format using (guessed) C and C++ source code syntax highlighting (style: standard) with prefixed line numbers and code folding option. Alternatively you can here view or download the uninterpreted source code file. For more information about "aacenc_ltp.c" see the Fossies "Dox" file reference documentation.

    1 /*
    2  * AAC encoder long term prediction extension
    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 long term prediction extension
   25  * @author Rostislav Pehlivanov ( atomnuker gmail com )
   26  */
   27 
   28 #include "aacenc_ltp.h"
   29 #include "aacenc_quantization.h"
   30 #include "aacenc_utils.h"
   31 
   32 /**
   33  * Encode LTP data.
   34  */
   35 void ff_aac_encode_ltp_info(AACEncContext *s, SingleChannelElement *sce,
   36                             int common_window)
   37 {
   38     int i;
   39     IndividualChannelStream *ics = &sce->ics;
   40     if (s->profile != FF_PROFILE_AAC_LTP || !ics->predictor_present)
   41         return;
   42     if (common_window)
   43         put_bits(&s->pb, 1, 0);
   44     put_bits(&s->pb, 1, ics->ltp.present);
   45     if (!ics->ltp.present)
   46         return;
   47     put_bits(&s->pb, 11, ics->ltp.lag);
   48     put_bits(&s->pb, 3,  ics->ltp.coef_idx);
   49     for (i = 0; i < FFMIN(ics->max_sfb, MAX_LTP_LONG_SFB); i++)
   50         put_bits(&s->pb, 1, ics->ltp.used[i]);
   51 }
   52 
   53 void ff_aac_ltp_insert_new_frame(AACEncContext *s)
   54 {
   55     int i, ch, tag, chans, cur_channel, start_ch = 0;
   56     ChannelElement *cpe;
   57     SingleChannelElement *sce;
   58     for (i = 0; i < s->chan_map[0]; i++) {
   59         cpe = &s->cpe[i];
   60         tag      = s->chan_map[i+1];
   61         chans    = tag == TYPE_CPE ? 2 : 1;
   62         for (ch = 0; ch < chans; ch++) {
   63             sce = &cpe->ch[ch];
   64             cur_channel = start_ch + ch;
   65             /* New sample + overlap */
   66             memcpy(&sce->ltp_state[0],    &sce->ltp_state[1024], 1024*sizeof(sce->ltp_state[0]));
   67             memcpy(&sce->ltp_state[1024], &s->planar_samples[cur_channel][2048], 1024*sizeof(sce->ltp_state[0]));
   68             memcpy(&sce->ltp_state[2048], &sce->ret_buf[0], 1024*sizeof(sce->ltp_state[0]));
   69             sce->ics.ltp.lag = 0;
   70         }
   71         start_ch += chans;
   72     }
   73 }
   74 
   75 static void get_lag(float *buf, const float *new, LongTermPrediction *ltp)
   76 {
   77     int i, j, lag = 0, max_corr = 0;
   78     float max_ratio = 0.0f;
   79     for (i = 0; i < 2048; i++) {
   80         float corr, s0 = 0.0f, s1 = 0.0f;
   81         const int start = FFMAX(0, i - 1024);
   82         for (j = start; j < 2048; j++) {
   83             const int idx = j - i + 1024;
   84             s0 += new[j]*buf[idx];
   85             s1 += buf[idx]*buf[idx];
   86         }
   87         corr = s1 > 0.0f ? s0/sqrt(s1) : 0.0f;
   88         if (corr > max_corr) {
   89             max_corr = corr;
   90             lag = i;
   91             max_ratio = corr/(2048-start);
   92         }
   93     }
   94     ltp->lag = FFMAX(av_clip_uintp2(lag, 11), 0);
   95     ltp->coef_idx = quant_array_idx(max_ratio, ltp_coef, 8);
   96     ltp->coef = ltp_coef[ltp->coef_idx];
   97 }
   98 
   99 static void generate_samples(float *buf, LongTermPrediction *ltp)
  100 {
  101     int i, samples_num = 2048;
  102     if (!ltp->lag) {
  103         ltp->present = 0;
  104         return;
  105     } else if (ltp->lag < 1024) {
  106         samples_num = ltp->lag + 1024;
  107     }
  108     for (i = 0; i < samples_num; i++)
  109         buf[i] = ltp->coef*buf[i + 2048 - ltp->lag];
  110     memset(&buf[i], 0, (2048 - i)*sizeof(float));
  111 }
  112 
  113 /**
  114  * Process LTP parameters
  115  * @see Patent WO2006070265A1
  116  */
  117 void ff_aac_update_ltp(AACEncContext *s, SingleChannelElement *sce)
  118 {
  119     float *pred_signal = &sce->ltp_state[0];
  120     const float *samples = &s->planar_samples[s->cur_channel][1024];
  121 
  122     if (s->profile != FF_PROFILE_AAC_LTP)
  123         return;
  124 
  125     /* Calculate lag */
  126     get_lag(pred_signal, samples, &sce->ics.ltp);
  127     generate_samples(pred_signal, &sce->ics.ltp);
  128 }
  129 
  130 void ff_aac_adjust_common_ltp(AACEncContext *s, ChannelElement *cpe)
  131 {
  132     int sfb, count = 0;
  133     SingleChannelElement *sce0 = &cpe->ch[0];
  134     SingleChannelElement *sce1 = &cpe->ch[1];
  135 
  136     if (!cpe->common_window ||
  137         sce0->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE ||
  138         sce1->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
  139         sce0->ics.ltp.present = 0;
  140         return;
  141     }
  142 
  143     for (sfb = 0; sfb < FFMIN(sce0->ics.max_sfb, MAX_LTP_LONG_SFB); sfb++) {
  144         int sum = sce0->ics.ltp.used[sfb] + sce1->ics.ltp.used[sfb];
  145         if (sum != 2) {
  146             sce0->ics.ltp.used[sfb] = 0;
  147         } else if (sum == 2) {
  148             count++;
  149         }
  150     }
  151 
  152     sce0->ics.ltp.present = !!count;
  153     sce0->ics.predictor_present = !!count;
  154 }
  155 
  156 /**
  157  * Mark LTP sfb's
  158  */
  159 void ff_aac_search_for_ltp(AACEncContext *s, SingleChannelElement *sce,
  160                            int common_window)
  161 {
  162     int w, g, w2, i, start = 0, count = 0;
  163     int saved_bits = -(15 + FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB));
  164     float *C34 = &s->scoefs[128*0], *PCD = &s->scoefs[128*1];
  165     float *PCD34 = &s->scoefs[128*2];
  166     const int max_ltp = FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB);
  167 
  168     if (sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
  169         if (sce->ics.ltp.lag) {
  170             memset(&sce->ltp_state[0], 0, 3072*sizeof(sce->ltp_state[0]));
  171             memset(&sce->ics.ltp, 0, sizeof(LongTermPrediction));
  172         }
  173         return;
  174     }
  175 
  176     if (!sce->ics.ltp.lag || s->lambda > 120.0f)
  177         return;
  178 
  179     for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
  180         start = 0;
  181         for (g = 0;  g < sce->ics.num_swb; g++) {
  182             int bits1 = 0, bits2 = 0;
  183             float dist1 = 0.0f, dist2 = 0.0f;
  184             if (w*16+g > max_ltp) {
  185                 start += sce->ics.swb_sizes[g];
  186                 continue;
  187             }
  188             for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
  189                 int bits_tmp1, bits_tmp2;
  190                 FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
  191                 for (i = 0; i < sce->ics.swb_sizes[g]; i++)
  192                     PCD[i] = sce->coeffs[start+(w+w2)*128+i] - sce->lcoeffs[start+(w+w2)*128+i];
  193                 s->abs_pow34(C34,  &sce->coeffs[start+(w+w2)*128],  sce->ics.swb_sizes[g]);
  194                 s->abs_pow34(PCD34, PCD, sce->ics.swb_sizes[g]);
  195                 dist1 += quantize_band_cost(s, &sce->coeffs[start+(w+w2)*128], C34, sce->ics.swb_sizes[g],
  196                                             sce->sf_idx[(w+w2)*16+g], sce->band_type[(w+w2)*16+g],
  197                                             s->lambda/band->threshold, INFINITY, &bits_tmp1, NULL, 0);
  198                 dist2 += quantize_band_cost(s, PCD, PCD34, sce->ics.swb_sizes[g],
  199                                             sce->sf_idx[(w+w2)*16+g],
  200                                             sce->band_type[(w+w2)*16+g],
  201                                             s->lambda/band->threshold, INFINITY, &bits_tmp2, NULL, 0);
  202                 bits1 += bits_tmp1;
  203                 bits2 += bits_tmp2;
  204             }
  205             if (dist2 < dist1 && bits2 < bits1) {
  206                 for (w2 = 0; w2 < sce->ics.group_len[w]; w2++)
  207                     for (i = 0; i < sce->ics.swb_sizes[g]; i++)
  208                         sce->coeffs[start+(w+w2)*128+i] -= sce->lcoeffs[start+(w+w2)*128+i];
  209                 sce->ics.ltp.used[w*16+g] = 1;
  210                 saved_bits += bits1 - bits2;
  211                 count++;
  212             }
  213             start += sce->ics.swb_sizes[g];
  214         }
  215     }
  216 
  217     sce->ics.ltp.present = !!count && (saved_bits >= 0);
  218     sce->ics.predictor_present = !!sce->ics.ltp.present;
  219 
  220     /* Reset any marked sfbs */
  221     if (!sce->ics.ltp.present && !!count) {
  222         for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
  223             start = 0;
  224             for (g = 0;  g < sce->ics.num_swb; g++) {
  225                 if (sce->ics.ltp.used[w*16+g]) {
  226                     for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
  227                         for (i = 0; i < sce->ics.swb_sizes[g]; i++) {
  228                             sce->coeffs[start+(w+w2)*128+i] += sce->lcoeffs[start+(w+w2)*128+i];
  229                         }
  230                     }
  231                 }
  232                 start += sce->ics.swb_sizes[g];
  233             }
  234         }
  235     }
  236 }