text: /*
   * AC-3 encoder float/fixed template
   * Copyright (c) 2000 Fabrice Bellard
   * Copyright (c) 2006-2011 Justin Ruggles <justin.ruggles@gmail.com>
   * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
   *
   * 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
   * AC-3 encoder float/fixed template
   */
  
  #include <stdint.h>
  
  #include "libavutil/internal.h"
  
  /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
  
  static void scale_coefficients(AC3EncodeContext *s);
  
  static void apply_window(void *dsp, SampleType *output,
                           const SampleType *input, const SampleType *window,
                           unsigned int len);
  
  static int normalize_samples(AC3EncodeContext *s);
  
  static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
  
  static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
  
  static void sum_square_butterfly(AC3EncodeContext *s, CoefSumType sum[4],
                                   const CoefType *coef0, const CoefType *coef1,
                                   int len);
  
  int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
  {
      int ch;
  
      FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
                       sizeof(*s->windowed_samples), alloc_fail);
      FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
                       alloc_fail);
      for (ch = 0; ch < s->channels; ch++) {
          FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
                            (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
                            alloc_fail);
      }
  
      return 0;
  alloc_fail:
      return AVERROR(ENOMEM);
  }
  
  
  /*
   * Copy input samples.
   * Channels are reordered from FFmpeg's default order to AC-3 order.
   */
  static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
  {
      int ch;
  
      /* copy and remap input samples */
      for (ch = 0; ch < s->channels; ch++) {
          /* copy last 256 samples of previous frame to the start of the current frame */
          memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
                 AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
  
          /* copy new samples for current frame */
          memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
                 samples[s->channel_map[ch]],
                 AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
      }
  }
  
  
  /*
   * Apply the MDCT to input samples to generate frequency coefficients.
   * This applies the KBD window and normalizes the input to reduce precision
   * loss due to fixed-point calculations.
   */
  static void apply_mdct(AC3EncodeContext *s)
  {
      int blk, ch;
  
      for (ch = 0; ch < s->channels; ch++) {
          for (blk = 0; blk < s->num_blocks; blk++) {
              AC3Block *block = &s->blocks[blk];
              const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
  
  #if CONFIG_AC3ENC_FLOAT
              apply_window(&s->fdsp, s->windowed_samples, input_samples,
                           s->mdct_window, AC3_WINDOW_SIZE);
  #else
              apply_window(&s->dsp, s->windowed_samples, input_samples,
                           s->mdct_window, AC3_WINDOW_SIZE);
  #endif
  
              if (s->fixed_point)
                  block->coeff_shift[ch+1] = normalize_samples(s);
  
              s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
                                 s->windowed_samples);
          }
      }
  }
  
  
  /*
   * Calculate coupling channel and coupling coordinates.
   */
  static void apply_channel_coupling(AC3EncodeContext *s)
  {
      LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
  #if CONFIG_AC3ENC_FLOAT
      LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
  #else
      int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
  #endif
      int av_uninit(blk), ch, bnd, i, j;
      CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
      int cpl_start, num_cpl_coefs;
  
      memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
  #if CONFIG_AC3ENC_FLOAT
      memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
  #endif
  
      /* align start to 16-byte boundary. align length to multiple of 32.
          note: coupling start bin % 4 will always be 1 */
      cpl_start     = s->start_freq[CPL_CH] - 1;
      num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
      cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
  
      /* calculate coupling channel from fbw channels */
      for (blk = 0; blk < s->num_blocks; blk++) {
          AC3Block *block = &s->blocks[blk];
          CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
          if (!block->cpl_in_use)
              continue;
          memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
          for (ch = 1; ch <= s->fbw_channels; ch++) {
              CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
              if (!block->channel_in_cpl[ch])
                  continue;
              for (i = 0; i < num_cpl_coefs; i++)
                  cpl_coef[i] += ch_coef[i];
          }
  
          /* coefficients must be clipped in order to be encoded */
          clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
      }
  
      /* calculate energy in each band in coupling channel and each fbw channel */
      /* TODO: possibly use SIMD to speed up energy calculation */
      bnd = 0;
      i = s->start_freq[CPL_CH];
      while (i < s->cpl_end_freq) {
          int band_size = s->cpl_band_sizes[bnd];
          for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
              for (blk = 0; blk < s->num_blocks; blk++) {
                  AC3Block *block = &s->blocks[blk];
                  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
                      continue;
                  for (j = 0; j < band_size; j++) {
                      CoefType v = block->mdct_coef[ch][i+j];
                      MAC_COEF(energy[blk][ch][bnd], v, v);
                  }
              }
          }
          i += band_size;
          bnd++;
      }
  
      /* calculate coupling coordinates for all blocks for all channels */
      for (blk = 0; blk < s->num_blocks; blk++) {
          AC3Block *block  = &s->blocks[blk];
          if (!block->cpl_in_use)
              continue;
          for (ch = 1; ch <= s->fbw_channels; ch++) {
              if (!block->channel_in_cpl[ch])
                  continue;
              for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
                  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
                                                            energy[blk][CPL_CH][bnd]);
              }
          }
      }
  
      /* determine which blocks to send new coupling coordinates for */
      for (blk = 0; blk < s->num_blocks; blk++) {
          AC3Block *block  = &s->blocks[blk];
          AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
  
          memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
  
          if (block->cpl_in_use) {
              /* send new coordinates if this is the first block, if previous
               * block did not use coupling but this block does, the channels
               * using coupling has changed from the previous block, or the
               * coordinate difference from the last block for any channel is
               * greater than a threshold value. */
              if (blk == 0 || !block0->cpl_in_use) {
                  for (ch = 1; ch <= s->fbw_channels; ch++)
                      block->new_cpl_coords[ch] = 1;
              } else {
                  for (ch = 1; ch <= s->fbw_channels; ch++) {
                      if (!block->channel_in_cpl[ch])
                          continue;
                      if (!block0->channel_in_cpl[ch]) {
                          block->new_cpl_coords[ch] = 1;
                      } else {
                          CoefSumType coord_diff = 0;
                          for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
                              coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
                                                  cpl_coords[blk  ][ch][bnd]);
                          }
                          coord_diff /= s->num_cpl_bands;
                          if (coord_diff > NEW_CPL_COORD_THRESHOLD)
                              block->new_cpl_coords[ch] = 1;
                      }
                  }
              }
          }
      }
  
      /* calculate final coupling coordinates, taking into account reusing of
         coordinates in successive blocks */
      for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
          blk = 0;
          while (blk < s->num_blocks) {
              int av_uninit(blk1);
              AC3Block *block  = &s->blocks[blk];
  
              if (!block->cpl_in_use) {
                  blk++;
                  continue;
              }
  
              for (ch = 1; ch <= s->fbw_channels; ch++) {
                  CoefSumType energy_ch, energy_cpl;
                  if (!block->channel_in_cpl[ch])
                      continue;
                  energy_cpl = energy[blk][CPL_CH][bnd];
                  energy_ch = energy[blk][ch][bnd];
                  blk1 = blk+1;
                  while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
                      if (s->blocks[blk1].cpl_in_use) {
                          energy_cpl += energy[blk1][CPL_CH][bnd];
                          energy_ch += energy[blk1][ch][bnd];
                      }
                      blk1++;
                  }
                  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
              }
              blk = blk1;
          }
      }
  
      /* calculate exponents/mantissas for coupling coordinates */
      for (blk = 0; blk < s->num_blocks; blk++) {
          AC3Block *block = &s->blocks[blk];
          if (!block->cpl_in_use)
              continue;
  
  #if CONFIG_AC3ENC_FLOAT
          s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
                                     cpl_coords[blk][1],
                                     s->fbw_channels * 16);
  #endif
          s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
                                      fixed_cpl_coords[blk][1],
                                      s->fbw_channels * 16);
  
          for (ch = 1; ch <= s->fbw_channels; ch++) {
              int bnd, min_exp, max_exp, master_exp;
  
              if (!block->new_cpl_coords[ch])
                  continue;
  
              /* determine master exponent */
              min_exp = max_exp = block->cpl_coord_exp[ch][0];
              for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
                  int exp = block->cpl_coord_exp[ch][bnd];
                  min_exp = FFMIN(exp, min_exp);
                  max_exp = FFMAX(exp, max_exp);
              }
              master_exp = ((max_exp - 15) + 2) / 3;
              master_exp = FFMAX(master_exp, 0);
              while (min_exp < master_exp * 3)
                  master_exp--;
              for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
                  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
                                                          master_exp * 3, 0, 15);
              }
              block->cpl_master_exp[ch] = master_exp;
  
              /* quantize mantissas */
              for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
                  int cpl_exp  = block->cpl_coord_exp[ch][bnd];
                  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
                  if (cpl_exp == 15)
                      cpl_mant >>= 1;
                  else
                      cpl_mant -= 16;
  
                  block->cpl_coord_mant[ch][bnd] = cpl_mant;
              }
          }
      }
  
      if (CONFIG_EAC3_ENCODER && s->eac3)
          ff_eac3_set_cpl_states(s);
  }
  
  
  /*
   * Determine rematrixing flags for each block and band.
   */
  static void compute_rematrixing_strategy(AC3EncodeContext *s)
  {
      int nb_coefs;
      int blk, bnd;
      AC3Block *block, *block0 = NULL;
  
      if (s->channel_mode != AC3_CHMODE_STEREO)
          return;
  
      for (blk = 0; blk < s->num_blocks; blk++) {
          block = &s->blocks[blk];
          block->new_rematrixing_strategy = !blk;
  
          block->num_rematrixing_bands = 4;
          if (block->cpl_in_use) {
              block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
              block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
              if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
                  block->new_rematrixing_strategy = 1;
          }
          nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
  
          if (!s->rematrixing_enabled) {
              block0 = block;
              continue;
          }
  
          for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
              /* calculate sum of squared coeffs for one band in one block */
              int start = ff_ac3_rematrix_band_tab[bnd];
              int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
              CoefSumType sum[4];
              sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
                                   block->mdct_coef[2] + start, end - start);
  
              /* compare sums to determine if rematrixing will be used for this band */
              if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
                  block->rematrixing_flags[bnd] = 1;
              else
                  block->rematrixing_flags[bnd] = 0;
  
              /* determine if new rematrixing flags will be sent */
              if (blk &&
                  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
                  block->new_rematrixing_strategy = 1;
              }
          }
          block0 = block;
      }
  }
  
  
  int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
                             const AVFrame *frame, int *got_packet_ptr)
  {
      AC3EncodeContext *s = avctx->priv_data;
      int ret;
  
      if (s->options.allow_per_frame_metadata) {
          ret = ff_ac3_validate_metadata(s);
          if (ret)
              return ret;
      }
  
      if (s->bit_alloc.sr_code == 1 || s->eac3)
          ff_ac3_adjust_frame_size(s);
  
      copy_input_samples(s, (SampleType **)frame->extended_data);
  
      apply_mdct(s);
  
      if (s->fixed_point)
          scale_coefficients(s);
  
      clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
                        AC3_MAX_COEFS * s->num_blocks * s->channels);
  
      s->cpl_on = s->cpl_enabled;
      ff_ac3_compute_coupling_strategy(s);
  
      if (s->cpl_on)
          apply_channel_coupling(s);
  
      compute_rematrixing_strategy(s);
  
      if (!s->fixed_point)
          scale_coefficients(s);
  
      ff_ac3_apply_rematrixing(s);
  
      ff_ac3_process_exponents(s);
  
      ret = ff_ac3_compute_bit_allocation(s);
      if (ret) {
          av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
          return ret;
      }
  
      ff_ac3_group_exponents(s);
  
      ff_ac3_quantize_mantissas(s);
  
      if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)) < 0)
          return ret;
      ff_ac3_output_frame(s, avpkt->data);
  
      if (frame->pts != AV_NOPTS_VALUE)
          avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
  
      *got_packet_ptr = 1;
      return 0;
  }
  