/*

  * AAC encoder long term prediction extension

  * Copyright (C) 2015 Rostislav Pehlivanov
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file

  * AAC encoder long term prediction extension

  * @author Rostislav Pehlivanov ( atomnuker gmail com )
  */
 
 #include "aacenc_ltp.h"
 #include "aacenc_quantization.h"
 #include "aacenc_utils.h"
 
 /**
  * Encode LTP data.
  */
 void ff_aac_encode_ltp_info(AACEncContext *s, SingleChannelElement *sce,
                             int common_window)
 {
     int i;
     IndividualChannelStream *ics = &sce->ics;
     if (s->profile != FF_PROFILE_AAC_LTP || !ics->predictor_present)
         return;
     if (common_window)
         put_bits(&s->pb, 1, 0);
     put_bits(&s->pb, 1, ics->ltp.present);
     if (!ics->ltp.present)
         return;
     put_bits(&s->pb, 11, ics->ltp.lag);
     put_bits(&s->pb, 3,  ics->ltp.coef_idx);
     for (i = 0; i < FFMIN(ics->max_sfb, MAX_LTP_LONG_SFB); i++)
         put_bits(&s->pb, 1, ics->ltp.used[i]);
 }
 
 void ff_aac_ltp_insert_new_frame(AACEncContext *s)
 {
     int i, ch, tag, chans, cur_channel, start_ch = 0;
     ChannelElement *cpe;
     SingleChannelElement *sce;
     for (i = 0; i < s->chan_map[0]; i++) {
         cpe = &s->cpe[i];
         tag      = s->chan_map[i+1];
         chans    = tag == TYPE_CPE ? 2 : 1;
         for (ch = 0; ch < chans; ch++) {
             sce = &cpe->ch[ch];
             cur_channel = start_ch + ch;
             /* New sample + overlap */
             memcpy(&sce->ltp_state[0],    &sce->ltp_state[1024], 1024*sizeof(sce->ltp_state[0]));
             memcpy(&sce->ltp_state[1024], &s->planar_samples[cur_channel][2048], 1024*sizeof(sce->ltp_state[0]));
             memcpy(&sce->ltp_state[2048], &sce->ret_buf[0], 1024*sizeof(sce->ltp_state[0]));

             sce->ics.ltp.lag = 0;

         }
         start_ch += chans;
     }
 }
 

 static void get_lag(float *buf, const float *new, LongTermPrediction *ltp)

 {

     int i, j, lag = 0, max_corr = 0;
     float max_ratio = 0.0f;

     for (i = 0; i < 2048; i++) {

         float corr, s0 = 0.0f, s1 = 0.0f;

         const int start = FFMAX(0, i - 1024);
         for (j = start; j < 2048; j++) {
             const int idx = j - i + 1024;

             s0 += new[j]*buf[idx];
             s1 += buf[idx]*buf[idx];

         }
         corr = s1 > 0.0f ? s0/sqrt(s1) : 0.0f;
         if (corr > max_corr) {
             max_corr = corr;
             lag = i;

             max_ratio = corr/(2048-start);

         }
     }

     ltp->lag = FFMAX(av_clip_uintp2(lag, 11), 0);
     ltp->coef_idx = quant_array_idx(max_ratio, ltp_coef, 8);
     ltp->coef = ltp_coef[ltp->coef_idx];
 }

 static void generate_samples(float *buf, LongTermPrediction *ltp)
 {
     int i, samples_num = 2048;
     if (!ltp->lag) {
         ltp->present = 0;

         return;

     } else if (ltp->lag < 1024) {
         samples_num = ltp->lag + 1024;
     }
     for (i = 0; i < samples_num; i++)
         buf[i] = ltp->coef*buf[i + 2048 - ltp->lag];
     memset(&buf[i], 0, (2048 - i)*sizeof(float));
 }
 
 /**
  * Process LTP parameters
  * @see Patent WO2006070265A1
  */
 void ff_aac_update_ltp(AACEncContext *s, SingleChannelElement *sce)
 {
     float *pred_signal = &sce->ltp_state[0];
     const float *samples = &s->planar_samples[s->cur_channel][1024];

     if (s->profile != FF_PROFILE_AAC_LTP)
         return;

     /* Calculate lag */
     get_lag(pred_signal, samples, &sce->ics.ltp);
     generate_samples(pred_signal, &sce->ics.ltp);

 }
 
 void ff_aac_adjust_common_ltp(AACEncContext *s, ChannelElement *cpe)
 {
     int sfb, count = 0;
     SingleChannelElement *sce0 = &cpe->ch[0];
     SingleChannelElement *sce1 = &cpe->ch[1];
 
     if (!cpe->common_window ||
         sce0->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE ||

         sce1->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
         sce0->ics.ltp.present = 0;

         return;

     }

 
     for (sfb = 0; sfb < FFMIN(sce0->ics.max_sfb, MAX_LTP_LONG_SFB); sfb++) {
         int sum = sce0->ics.ltp.used[sfb] + sce1->ics.ltp.used[sfb];
         if (sum != 2) {
             sce0->ics.ltp.used[sfb] = 0;
         } else if (sum == 2) {
             count++;
         }
     }
 
     sce0->ics.ltp.present = !!count;
     sce0->ics.predictor_present = !!count;
 }
 
 /**
  * Mark LTP sfb's
  */
 void ff_aac_search_for_ltp(AACEncContext *s, SingleChannelElement *sce,
                            int common_window)
 {
     int w, g, w2, i, start = 0, count = 0;
     int saved_bits = -(15 + FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB));
     float *C34 = &s->scoefs[128*0], *PCD = &s->scoefs[128*1];
     float *PCD34 = &s->scoefs[128*2];
     const int max_ltp = FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB);
 

     if (sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
         if (sce->ics.ltp.lag) {

             memset(&sce->ltp_state[0], 0, 3072*sizeof(sce->ltp_state[0]));

             memset(&sce->ics.ltp, 0, sizeof(LongTermPrediction));
         }
         return;
     }
 

     if (!sce->ics.ltp.lag || s->lambda > 120.0f)

         return;
 
     for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
         start = 0;
         for (g = 0;  g < sce->ics.num_swb; g++) {
             int bits1 = 0, bits2 = 0;
             float dist1 = 0.0f, dist2 = 0.0f;
             if (w*16+g > max_ltp) {
                 start += sce->ics.swb_sizes[g];
                 continue;
             }
             for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                 int bits_tmp1, bits_tmp2;
                 FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
                 for (i = 0; i < sce->ics.swb_sizes[g]; i++)
                     PCD[i] = sce->coeffs[start+(w+w2)*128+i] - sce->lcoeffs[start+(w+w2)*128+i];

                 s->abs_pow34(C34,  &sce->coeffs[start+(w+w2)*128],  sce->ics.swb_sizes[g]);
                 s->abs_pow34(PCD34, PCD, sce->ics.swb_sizes[g]);

                 dist1 += quantize_band_cost(s, &sce->coeffs[start+(w+w2)*128], C34, sce->ics.swb_sizes[g],
                                             sce->sf_idx[(w+w2)*16+g], sce->band_type[(w+w2)*16+g],
                                             s->lambda/band->threshold, INFINITY, &bits_tmp1, NULL, 0);
                 dist2 += quantize_band_cost(s, PCD, PCD34, sce->ics.swb_sizes[g],
                                             sce->sf_idx[(w+w2)*16+g],
                                             sce->band_type[(w+w2)*16+g],
                                             s->lambda/band->threshold, INFINITY, &bits_tmp2, NULL, 0);
                 bits1 += bits_tmp1;
                 bits2 += bits_tmp2;
             }
             if (dist2 < dist1 && bits2 < bits1) {
                 for (w2 = 0; w2 < sce->ics.group_len[w]; w2++)
                     for (i = 0; i < sce->ics.swb_sizes[g]; i++)
                         sce->coeffs[start+(w+w2)*128+i] -= sce->lcoeffs[start+(w+w2)*128+i];
                 sce->ics.ltp.used[w*16+g] = 1;
                 saved_bits += bits1 - bits2;
                 count++;
             }
             start += sce->ics.swb_sizes[g];
         }
     }
 
     sce->ics.ltp.present = !!count && (saved_bits >= 0);
     sce->ics.predictor_present = !!sce->ics.ltp.present;
 
     /* Reset any marked sfbs */
     if (!sce->ics.ltp.present && !!count) {
         for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
             start = 0;
             for (g = 0;  g < sce->ics.num_swb; g++) {
                 if (sce->ics.ltp.used[w*16+g]) {
                     for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                         for (i = 0; i < sce->ics.swb_sizes[g]; i++) {
                             sce->coeffs[start+(w+w2)*128+i] += sce->lcoeffs[start+(w+w2)*128+i];
                         }
                     }
                 }
                 start += sce->ics.swb_sizes[g];
             }
         }
     }
 }