/*
  * AAC encoder intensity stereo
  * 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 Intensity Stereo
  * @author Rostislav Pehlivanov ( atomnuker gmail com )
  */
 
 #include "aacenc.h"
 #include "aacenc_utils.h"
 #include "aacenc_is.h"
 #include "aacenc_quantization.h"
 

 struct AACISError ff_aac_is_encoding_err(AACEncContext *s, ChannelElement *cpe,
                                          int start, int w, int g, float ener0,

                                          float ener1, float ener01,
                                          int use_pcoeffs, int phase)

 {
     int i, w2;

     SingleChannelElement *sce0 = &cpe->ch[0];
     SingleChannelElement *sce1 = &cpe->ch[1];
     float *L = use_pcoeffs ? sce0->pcoeffs : sce0->coeffs;
     float *R = use_pcoeffs ? sce1->pcoeffs : sce1->coeffs;

     float *L34 = &s->scoefs[256*0], *R34 = &s->scoefs[256*1];
     float *IS  = &s->scoefs[256*2], *I34 = &s->scoefs[256*3];
     float dist1 = 0.0f, dist2 = 0.0f;

     struct AACISError is_error = {0};

     if (ener01 <= 0 || ener0 <= 0) {
         is_error.pass = 0;
         return is_error;
     }
 

     for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
         FFPsyBand *band0 = &s->psy.ch[s->cur_channel+0].psy_bands[(w+w2)*16+g];
         FFPsyBand *band1 = &s->psy.ch[s->cur_channel+1].psy_bands[(w+w2)*16+g];

         int is_band_type, is_sf_idx = FFMAX(1, sce0->sf_idx[w*16+g]-4);

         float e01_34 = phase*pos_pow34(ener1/ener0);

         float maxval, dist_spec_err = 0.0f;
         float minthr = FFMIN(band0->threshold, band1->threshold);

         for (i = 0; i < sce0->ics.swb_sizes[g]; i++)
             IS[i] = (L[start+(w+w2)*128+i] + phase*R[start+(w+w2)*128+i])*sqrt(ener0/ener01);

         s->abs_pow34(L34, &L[start+(w+w2)*128], sce0->ics.swb_sizes[g]);
         s->abs_pow34(R34, &R[start+(w+w2)*128], sce0->ics.swb_sizes[g]);
         s->abs_pow34(I34, IS,                   sce0->ics.swb_sizes[g]);

         maxval = find_max_val(1, sce0->ics.swb_sizes[g], I34);
         is_band_type = find_min_book(maxval, is_sf_idx);

         dist1 += quantize_band_cost(s, &L[start + (w+w2)*128], L34,

                                     sce0->ics.swb_sizes[g],

                                     sce0->sf_idx[w*16+g],
                                     sce0->band_type[w*16+g],

                                     s->lambda / band0->threshold, INFINITY, NULL, NULL, 0);

         dist1 += quantize_band_cost(s, &R[start + (w+w2)*128], R34,

                                     sce1->ics.swb_sizes[g],

                                     sce1->sf_idx[w*16+g],
                                     sce1->band_type[w*16+g],

                                     s->lambda / band1->threshold, INFINITY, NULL, NULL, 0);

         dist2 += quantize_band_cost(s, IS, I34, sce0->ics.swb_sizes[g],
                                     is_sf_idx, is_band_type,

                                     s->lambda / minthr, INFINITY, NULL, NULL, 0);

         for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
             dist_spec_err += (L34[i] - I34[i])*(L34[i] - I34[i]);
             dist_spec_err += (R34[i] - I34[i]*e01_34)*(R34[i] - I34[i]*e01_34);
         }
         dist_spec_err *= s->lambda / minthr;
         dist2 += dist_spec_err;
     }
 
     is_error.pass = dist2 <= dist1;
     is_error.phase = phase;

     is_error.error = dist2 - dist1;

     is_error.dist1 = dist1;
     is_error.dist2 = dist2;

     is_error.ener01 = ener01;

 
     return is_error;
 }
 

 void ff_aac_search_for_is(AACEncContext *s, AVCodecContext *avctx, ChannelElement *cpe)

 {
     SingleChannelElement *sce0 = &cpe->ch[0];
     SingleChannelElement *sce1 = &cpe->ch[1];

     int start = 0, count = 0, w, w2, g, i, prev_sf1 = -1, prev_bt = -1, prev_is = 0;

     const float freq_mult = avctx->sample_rate/(1024.0f/sce0->ics.num_windows)/2.0f;

     uint8_t nextband1[128];

 
     if (!cpe->common_window)
         return;
 

     /** Scout out next nonzero bands */
     ff_init_nextband_map(sce1, nextband1);
 

     for (w = 0; w < sce0->ics.num_windows; w += sce0->ics.group_len[w]) {
         start = 0;
         for (g = 0;  g < sce0->ics.num_swb; g++) {
             if (start*freq_mult > INT_STEREO_LOW_LIMIT*(s->lambda/170.0f) &&
                 cpe->ch[0].band_type[w*16+g] != NOISE_BT && !cpe->ch[0].zeroes[w*16+g] &&

                 cpe->ch[1].band_type[w*16+g] != NOISE_BT && !cpe->ch[1].zeroes[w*16+g] &&
                 ff_sfdelta_can_remove_band(sce1, nextband1, prev_sf1, w*16+g)) {

                 float ener0 = 0.0f, ener1 = 0.0f, ener01 = 0.0f, ener01p = 0.0f;

                 struct AACISError ph_err1, ph_err2, *best;

                 for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
                     for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {

                         float coef0 = sce0->coeffs[start+(w+w2)*128+i];
                         float coef1 = sce1->coeffs[start+(w+w2)*128+i];

                         ener0  += coef0*coef0;
                         ener1  += coef1*coef1;

                         ener01 += (coef0 + coef1)*(coef0 + coef1);

                         ener01p += (coef0 - coef1)*(coef0 - coef1);

                     }
                 }

                 ph_err1 = ff_aac_is_encoding_err(s, cpe, start, w, g,

                                                  ener0, ener1, ener01p, 0, -1);

                 ph_err2 = ff_aac_is_encoding_err(s, cpe, start, w, g,

                                                  ener0, ener1, ener01, 0, +1);

                 best = (ph_err1.pass && ph_err1.error < ph_err2.error) ? &ph_err1 : &ph_err2;
                 if (best->pass) {

                     cpe->is_mask[w*16+g] = 1;

                     cpe->ms_mask[w*16+g] = 0;

                     cpe->ch[0].is_ener[w*16+g] = sqrt(ener0 / best->ener01);

                     cpe->ch[1].is_ener[w*16+g] = ener0/ener1;

                     cpe->ch[1].band_type[w*16+g] = (best->phase > 0) ? INTENSITY_BT : INTENSITY_BT2;

                     if (prev_is && prev_bt != cpe->ch[1].band_type[w*16+g]) {
                         /** Flip M/S mask and pick the other CB, since it encodes more efficiently */
                         cpe->ms_mask[w*16+g] = 1;
                         cpe->ch[1].band_type[w*16+g] = (best->phase > 0) ? INTENSITY_BT2 : INTENSITY_BT;
                     }
                     prev_bt = cpe->ch[1].band_type[w*16+g];

                     count++;
                 }
             }

             if (!sce1->zeroes[w*16+g] && sce1->band_type[w*16+g] < RESERVED_BT)
                 prev_sf1 = sce1->sf_idx[w*16+g];

             prev_is = cpe->is_mask[w*16+g];

             start += sce0->ics.swb_sizes[g];
         }
     }
     cpe->is_mode = !!count;
 }