text: /*
   * ATRAC9 decoder
   * Copyright (c) 2018 Rostislav Pehlivanov <atomnuker@gmail.com>
   *
   * 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
   */
  
  #include "internal.h"
  #include "get_bits.h"
  #include "fft.h"
  #include "atrac9tab.h"
  #include "libavutil/lfg.h"
  #include "libavutil/float_dsp.h"
  
  typedef struct ATRAC9ChannelData {
      int band_ext;
      int q_unit_cnt;
      int band_ext_data[4];
      int32_t scalefactors[31];
      int32_t scalefactors_prev[31];
  
      int precision_coarse[30];
      int precision_fine[30];
      int precision_mask[30];
  
      int codebookset[30];
  
      int32_t q_coeffs_coarse[256];
      int32_t q_coeffs_fine[256];
  
      DECLARE_ALIGNED(32, float, coeffs  )[256];
      DECLARE_ALIGNED(32, float, prev_win)[128];
  } ATRAC9ChannelData;
  
  typedef struct ATRAC9BlockData {
      ATRAC9ChannelData channel[2];
  
      /* Base */
      int band_count;
      int q_unit_cnt;
      int q_unit_cnt_prev;
  
      /* Stereo block only */
      int stereo_q_unit;
  
      /* Band extension only */
      int has_band_ext;
      int has_band_ext_data;
      int band_ext_q_unit;
  
      /* Gradient */
      int grad_mode;
      int grad_boundary;
      int gradient[31];
  
      /* Stereo */
      int cpe_base_channel;
      int is_signs[30];
  
      int reuseable;
  
  } ATRAC9BlockData;
  
  typedef struct ATRAC9Context {
      AVCodecContext *avctx;
      AVFloatDSPContext *fdsp;
      FFTContext imdct;
      ATRAC9BlockData block[5];
      AVLFG lfg;
  
      /* Set on init */
      int frame_log2;
      int avg_frame_size;
      int frame_count;
      int samplerate_idx;
      const ATRAC9BlockConfig *block_config;
  
      /* Generated on init */
      VLC sf_vlc[2][8];            /* Signed/unsigned, length */
      VLC coeff_vlc[2][8][4];      /* Cookbook, precision, cookbook index */
      uint8_t alloc_curve[48][48];
      DECLARE_ALIGNED(32, float, imdct_win)[256];
  
      DECLARE_ALIGNED(32, float, temp)[256];
  } ATRAC9Context;
  
  static inline int parse_gradient(ATRAC9Context *s, ATRAC9BlockData *b,
                                   GetBitContext *gb)
  {
      int grad_range[2];
      int grad_value[2];
      int values, sign, base;
      uint8_t *curve;
      float scale;
  
      b->grad_mode = get_bits(gb, 2);
      if (b->grad_mode) {
          grad_range[0] = get_bits(gb, 5);
          grad_range[1] = 31;
          grad_value[0] = get_bits(gb, 5);
          grad_value[1] = 31;
      } else {
          grad_range[0] = get_bits(gb, 6);
          grad_range[1] = get_bits(gb, 6) + 1;
          grad_value[0] = get_bits(gb, 5);
          grad_value[1] = get_bits(gb, 5);
      }
      b->grad_boundary = get_bits(gb, 4);
  
      if (grad_range[0] >= grad_range[1] || grad_range[1] > 31)
          return AVERROR_INVALIDDATA;
  
      if (grad_value[0] > 31 || grad_value[1] > 31)
          return AVERROR_INVALIDDATA;
  
      if (b->grad_boundary > b->q_unit_cnt)
          return AVERROR_INVALIDDATA;
  
      values    = grad_value[1] - grad_value[0];
      sign      = 1 - 2*(values < 0);
      base      = grad_value[0] + sign;
      scale     = (FFABS(values) - 1) / 31.0f;
      curve     = s->alloc_curve[grad_range[1] - grad_range[0] - 1];
  
      for (int i = 0; i <= b->q_unit_cnt; i++)
          b->gradient[i] = grad_value[i >= grad_range[0]];
  
      for (int i = grad_range[0]; i < grad_range[1]; i++)
          b->gradient[i] = base + sign*((int)(scale*curve[i - grad_range[0]]));
  
      return 0;
  }
  
  static inline void calc_precision(ATRAC9Context *s, ATRAC9BlockData *b,
                                    ATRAC9ChannelData *c)
  {
      memset(c->precision_mask, 0, sizeof(c->precision_mask));
      for (int i = 1; i < b->q_unit_cnt; i++) {
          const int delta = FFABS(c->scalefactors[i] - c->scalefactors[i - 1]) - 1;
          if (delta > 0) {
              const int neg = c->scalefactors[i - 1] > c->scalefactors[i];
              c->precision_mask[i - neg] += FFMIN(delta, 5);
          }
      }
  
      if (b->grad_mode) {
          for (int i = 0; i < b->q_unit_cnt; i++) {
              c->precision_coarse[i] = c->scalefactors[i];
              c->precision_coarse[i] += c->precision_mask[i] - b->gradient[i];
              if (c->precision_coarse[i] < 0)
                  continue;
              switch (b->grad_mode) {
              case 1:
                  c->precision_coarse[i] >>= 1;
                  break;
              case 2:
                  c->precision_coarse[i] = (3 * c->precision_coarse[i]) >> 3;
                  break;
              case 3:
                  c->precision_coarse[i] >>= 2;
                  break;
              }
          }
      } else {
          for (int i = 0; i < b->q_unit_cnt; i++)
              c->precision_coarse[i] = c->scalefactors[i] - b->gradient[i];
      }
  
  
      for (int i = 0; i < b->q_unit_cnt; i++)
          c->precision_coarse[i] = FFMAX(c->precision_coarse[i], 1);
  
      for (int i = 0; i < b->grad_boundary; i++)
          c->precision_coarse[i]++;
  
      for (int i = 0; i < b->q_unit_cnt; i++) {
          c->precision_fine[i] = 0;
          if (c->precision_coarse[i] > 15) {
              c->precision_fine[i] = FFMIN(c->precision_coarse[i], 30) - 15;
              c->precision_coarse[i] = 15;
          }
      }
  }
  
  static inline int parse_band_ext(ATRAC9Context *s, ATRAC9BlockData *b,
                                   GetBitContext *gb, int stereo)
  {
      int ext_band = 0;
  
      if (b->has_band_ext) {
          if (b->q_unit_cnt < 13 || b->q_unit_cnt > 20)
              return AVERROR_INVALIDDATA;
          ext_band = at9_tab_band_ext_group[b->q_unit_cnt - 13][2];
          if (stereo) {
              b->channel[1].band_ext = get_bits(gb, 2);
              b->channel[1].band_ext = ext_band > 2 ? b->channel[1].band_ext : 4;
          } else {
              skip_bits1(gb);
          }
      }
  
      b->has_band_ext_data = get_bits1(gb);
      if (!b->has_band_ext_data)
          return 0;
  
      if (!b->has_band_ext) {
          skip_bits(gb, 2);
          skip_bits_long(gb, get_bits(gb, 5));
          return 0;
      }
  
      b->channel[0].band_ext = get_bits(gb, 2);
      b->channel[0].band_ext = ext_band > 2 ? b->channel[0].band_ext : 4;
  
      if (!get_bits(gb, 5)) {
          for (int i = 0; i <= stereo; i++) {
              ATRAC9ChannelData *c = &b->channel[i];
              const int count = at9_tab_band_ext_cnt[c->band_ext][ext_band];
              for (int j = 0; j < count; j++) {
                  int len = at9_tab_band_ext_lengths[c->band_ext][ext_band][j];
                  c->band_ext_data[j] = av_clip_uintp2_c(c->band_ext_data[j], len);
              }
          }
  
          return 0;
      }
  
      for (int i = 0; i <= stereo; i++) {
          ATRAC9ChannelData *c = &b->channel[i];
          const int count = at9_tab_band_ext_cnt[c->band_ext][ext_band];
          for (int j = 0; j < count; j++) {
              int len = at9_tab_band_ext_lengths[c->band_ext][ext_band][j];
              c->band_ext_data[j] = get_bits(gb, len);
          }
      }
  
      return 0;
  }
  
  static inline int read_scalefactors(ATRAC9Context *s, ATRAC9BlockData *b,
                                      ATRAC9ChannelData *c, GetBitContext *gb,
                                      int channel_idx, int first_in_pkt)
  {
      static const int mode_map[2][4] = { { 0, 1, 2, 3 }, { 0, 2, 3, 4 } };
      const int mode = mode_map[channel_idx][get_bits(gb, 2)];
  
      memset(c->scalefactors, 0, sizeof(c->scalefactors));
  
      if (first_in_pkt && (mode == 4 || ((mode == 3) && !channel_idx))) {
          av_log(s->avctx, AV_LOG_ERROR, "Invalid scalefactor coding mode!\n");
          return AVERROR_INVALIDDATA;
      }
  
      switch (mode) {
      case 0: { /* VLC delta offset */
          const uint8_t *sf_weights = at9_tab_sf_weights[get_bits(gb, 3)];
          const int base = get_bits(gb, 5);
          const int len = get_bits(gb, 2) + 3;
          const VLC *tab = &s->sf_vlc[0][len];
  
          c->scalefactors[0] = get_bits(gb, len);
  
          for (int i = 1; i < b->band_ext_q_unit; i++) {
              int val = c->scalefactors[i - 1] + get_vlc2(gb, tab->table, 9, 2);
              c->scalefactors[i] = val & ((1 << len) - 1);
          }
  
          for (int i = 0; i < b->band_ext_q_unit; i++)
              c->scalefactors[i] += base - sf_weights[i];
  
          break;
      }
      case 1: { /* CLC offset */
          const int len = get_bits(gb, 2) + 2;
          const int base = len < 5 ? get_bits(gb, 5) : 0;
          for (int i = 0; i < b->band_ext_q_unit; i++)
              c->scalefactors[i] = base + get_bits(gb, len);
          break;
      }
      case 2:
      case 4: { /* VLC dist to baseline */
          const int *baseline = mode == 4 ? c->scalefactors_prev :
                                channel_idx ? b->channel[0].scalefactors :
                                c->scalefactors_prev;
          const int baseline_len = mode == 4 ? b->q_unit_cnt_prev :
                                   channel_idx ? b->band_ext_q_unit :
                                   b->q_unit_cnt_prev;
  
          const int len = get_bits(gb, 2) + 2;
          const int unit_cnt = FFMIN(b->band_ext_q_unit, baseline_len);
          const VLC *tab = &s->sf_vlc[1][len];
  
          for (int i = 0; i < unit_cnt; i++) {
              int dist = get_vlc2(gb, tab->table, 9, 2);
              c->scalefactors[i] = baseline[i] + dist;
          }
  
          for (int i = unit_cnt; i < b->band_ext_q_unit; i++)
              c->scalefactors[i] = get_bits(gb, 5);
  
          break;
      }
      case 3: { /* VLC offset with baseline */
          const int *baseline = channel_idx ? b->channel[0].scalefactors :
                                c->scalefactors_prev;
          const int baseline_len = channel_idx ? b->band_ext_q_unit :
                                   b->q_unit_cnt_prev;
  
          const int base = get_bits(gb, 5) - (1 << (5 - 1));
          const int len = get_bits(gb, 2) + 1;
          const int unit_cnt = FFMIN(b->band_ext_q_unit, baseline_len);
          const VLC *tab = &s->sf_vlc[0][len];
  
          c->scalefactors[0] = get_bits(gb, len);
  
          for (int i = 1; i < unit_cnt; i++) {
              int val = c->scalefactors[i - 1] + get_vlc2(gb, tab->table, 9, 2);
              c->scalefactors[i] = val & ((1 << len) - 1);
          }
  
          for (int i = 0; i < unit_cnt; i++)
              c->scalefactors[i] += base + baseline[i];
  
          for (int i = unit_cnt; i < b->band_ext_q_unit; i++)
              c->scalefactors[i] = get_bits(gb, 5);
          break;
      }
      }
  
      for (int i = 0; i < b->band_ext_q_unit; i++)
          if (c->scalefactors[i] < 0 || c->scalefactors[i] > 31)
              return AVERROR_INVALIDDATA;
  
      memcpy(c->scalefactors_prev, c->scalefactors, sizeof(c->scalefactors));
  
      return 0;
  }
  
  static inline void calc_codebook_idx(ATRAC9Context *s, ATRAC9BlockData *b,
                                       ATRAC9ChannelData *c)
  {
      int avg = 0;
      const int last_sf = c->scalefactors[c->q_unit_cnt];
  
      memset(c->codebookset, 0, sizeof(c->codebookset));
  
      if (c->q_unit_cnt <= 1)
          return;
      if (s->samplerate_idx > 7)
          return;
  
      c->scalefactors[c->q_unit_cnt] = c->scalefactors[c->q_unit_cnt - 1];
  
      if (c->q_unit_cnt > 12) {
          for (int i = 0; i < 12; i++)
              avg += c->scalefactors[i];
          avg = (avg + 6) / 12;
      }
  
      for (int i = 8; i < c->q_unit_cnt; i++) {
          const int prev = c->scalefactors[i - 1];
          const int cur  = c->scalefactors[i    ];
          const int next = c->scalefactors[i + 1];
          const int min  = FFMIN(prev, next);
          if ((cur - min >= 3 || 2*cur - prev - next >= 3))
              c->codebookset[i] = 1;
      }
  
  
      for (int i = 12; i < c->q_unit_cnt; i++) {
          const int cur = c->scalefactors[i];
          const int cnd = at9_q_unit_to_coeff_cnt[i] == 16;
          const int min = FFMIN(c->scalefactors[i + 1], c->scalefactors[i - 1]);
          if (c->codebookset[i])
              continue;
  
          c->codebookset[i] = (((cur - min) >= 2) && (cur >= (avg - cnd)));
      }
  
      c->scalefactors[c->q_unit_cnt] = last_sf;
  }
  
  static inline void read_coeffs_coarse(ATRAC9Context *s, ATRAC9BlockData *b,
                                        ATRAC9ChannelData *c, GetBitContext *gb)
  {
      const int max_prec = s->samplerate_idx > 7 ? 1 : 7;
  
      memset(c->q_coeffs_coarse, 0, sizeof(c->q_coeffs_coarse));
  
      for (int i = 0; i < c->q_unit_cnt; i++) {
          int *coeffs = &c->q_coeffs_coarse[at9_q_unit_to_coeff_idx[i]];
          const int bands = at9_q_unit_to_coeff_cnt[i];
          const int prec = c->precision_coarse[i] + 1;
  
          if (prec <= max_prec) {
              const int cb = c->codebookset[i];
              const int cbi = at9_q_unit_to_codebookidx[i];
              const VLC *tab = &s->coeff_vlc[cb][prec][cbi];
              const HuffmanCodebook *huff = &at9_huffman_coeffs[cb][prec][cbi];
              const int groups = bands >> huff->value_cnt_pow;
  
              for (int j = 0; j < groups; j++) {
                  uint16_t val = get_vlc2(gb, tab->table, 9, huff->max_bit_size);
  
                  for (int k = 0; k < huff->value_cnt; k++) {
                      coeffs[k] = sign_extend(val, huff->value_bits);
                      val >>= huff->value_bits;
                  }
  
                  coeffs += huff->value_cnt;
              }
          } else {
              for (int j = 0; j < bands; j++)
                  coeffs[j] = sign_extend(get_bits(gb, prec), prec);
          }
      }
  }
  
  static inline void read_coeffs_fine(ATRAC9Context *s, ATRAC9BlockData *b,
                                      ATRAC9ChannelData *c, GetBitContext *gb)
  {
      memset(c->q_coeffs_fine, 0, sizeof(c->q_coeffs_fine));
  
      for (int i = 0; i < c->q_unit_cnt; i++) {
          const int start = at9_q_unit_to_coeff_idx[i + 0];
          const int end   = at9_q_unit_to_coeff_idx[i + 1];
          const int len   = c->precision_fine[i] + 1;
  
          if (c->precision_fine[i] <= 0)
              continue;
  
          for (int j = start; j < end; j++)
              c->q_coeffs_fine[j] = sign_extend(get_bits(gb, len), len);
      }
  }
  
  static inline void dequantize(ATRAC9Context *s, ATRAC9BlockData *b,
                                ATRAC9ChannelData *c)
  {
      memset(c->coeffs, 0, sizeof(c->coeffs));
  
      for (int i = 0; i < c->q_unit_cnt; i++) {
          const int start = at9_q_unit_to_coeff_idx[i + 0];
          const int end   = at9_q_unit_to_coeff_idx[i + 1];
  
          const float coarse_c = at9_quant_step_coarse[c->precision_coarse[i]];
          const float fine_c   = at9_quant_step_fine[c->precision_fine[i]];
  
          for (int j = start; j < end; j++) {
              const float vc = c->q_coeffs_coarse[j] * coarse_c;
              const float vf = c->q_coeffs_fine[j]   * fine_c;
              c->coeffs[j] = vc + vf;
          }
      }
  }
  
  static inline void apply_intensity_stereo(ATRAC9Context *s, ATRAC9BlockData *b,
                                            const int stereo)
  {
      float *src = b->channel[ b->cpe_base_channel].coeffs;
      float *dst = b->channel[!b->cpe_base_channel].coeffs;
  
      if (!stereo)
          return;
  
      if (b->q_unit_cnt <= b->stereo_q_unit)
          return;
  
      for (int i = b->stereo_q_unit; i < b->q_unit_cnt; i++) {
          const int sign  = b->is_signs[i];
          const int start = at9_q_unit_to_coeff_idx[i + 0];
          const int end   = at9_q_unit_to_coeff_idx[i + 1];
          for (int j = start; j < end; j++)
              dst[j] = sign*src[j];
      }
  }
  
  static inline void apply_scalefactors(ATRAC9Context *s, ATRAC9BlockData *b,
                                        const int stereo)
  {
      for (int i = 0; i <= stereo; i++) {
          float *coeffs = b->channel[i].coeffs;
          for (int j = 0; j < b->q_unit_cnt; j++) {
              const int start = at9_q_unit_to_coeff_idx[j + 0];
              const int end   = at9_q_unit_to_coeff_idx[j + 1];
              const int scalefactor = b->channel[i].scalefactors[j];
              const float scale = at9_scalefactor_c[scalefactor];
              for (int k = start; k < end; k++)
                  coeffs[k] *= scale;
          }
      }
  }
  
  static inline void fill_with_noise(ATRAC9Context *s, ATRAC9ChannelData *c,
                                     int start, int count)
  {
      float maxval = 0.0f;
      for (int i = 0; i < count; i += 2) {
          double tmp[2];
          av_bmg_get(&s->lfg, tmp);
          c->coeffs[start + i + 0] = tmp[0];
          c->coeffs[start + i + 1] = tmp[1];
          maxval = FFMAX(FFMAX(FFABS(tmp[0]), FFABS(tmp[1])), maxval);
      }
      /* Normalize */
      for (int i = 0; i < count; i++)
          c->coeffs[start + i] /= maxval;
  }
  
  static inline void scale_band_ext_coeffs(ATRAC9ChannelData *c, float sf[6],
                                           const int s_unit, const int e_unit)
  {
      for (int i = s_unit; i < e_unit; i++) {
          const int start = at9_q_unit_to_coeff_idx[i + 0];
          const int end   = at9_q_unit_to_coeff_idx[i + 1];
          for (int j = start; j < end; j++)
              c->coeffs[j] *= sf[i - s_unit];
      }
  }
  
  static inline void apply_band_extension(ATRAC9Context *s, ATRAC9BlockData *b,
                                         const int stereo)
  {
      const int g_units[4] = { /* A, B, C, total units */
          b->q_unit_cnt,
          at9_tab_band_ext_group[b->q_unit_cnt - 13][0],
          at9_tab_band_ext_group[b->q_unit_cnt - 13][1],
          FFMAX(g_units[2], 22),
      };
  
      const int g_bins[4] = { /* A, B, C, total bins */
          at9_q_unit_to_coeff_idx[g_units[0]],
          at9_q_unit_to_coeff_idx[g_units[1]],
          at9_q_unit_to_coeff_idx[g_units[2]],
          at9_q_unit_to_coeff_idx[g_units[3]],
      };
  
      for (int ch = 0; ch <= stereo; ch++) {
          ATRAC9ChannelData *c = &b->channel[ch];
  
          /* Mirror the spectrum */
          for (int i = 0; i < 3; i++)
              for (int j = 0; j < (g_bins[i + 1] - g_bins[i + 0]); j++)
                  c->coeffs[g_bins[i] + j] = c->coeffs[g_bins[i] - j - 1];
  
          switch (c->band_ext) {
          case 0: {
              float sf[6] = { 0.0f };
              const int l = g_units[3] - g_units[0] - 1;
              const int n_start = at9_q_unit_to_coeff_idx[g_units[3] - 1];
              const int n_cnt   = at9_q_unit_to_coeff_cnt[g_units[3] - 1];
              switch (at9_tab_band_ext_group[b->q_unit_cnt - 13][2]) {
              case 3:
                  sf[0] = at9_band_ext_scales_m0[0][0][c->band_ext_data[0]];
                  sf[1] = at9_band_ext_scales_m0[0][1][c->band_ext_data[0]];
                  sf[2] = at9_band_ext_scales_m0[0][2][c->band_ext_data[1]];
                  sf[3] = at9_band_ext_scales_m0[0][3][c->band_ext_data[2]];
                  sf[4] = at9_band_ext_scales_m0[0][4][c->band_ext_data[3]];
                  break;
              case 4:
                  sf[0] = at9_band_ext_scales_m0[1][0][c->band_ext_data[0]];
                  sf[1] = at9_band_ext_scales_m0[1][1][c->band_ext_data[0]];
                  sf[2] = at9_band_ext_scales_m0[1][2][c->band_ext_data[1]];
                  sf[3] = at9_band_ext_scales_m0[1][3][c->band_ext_data[2]];
                  sf[4] = at9_band_ext_scales_m0[1][4][c->band_ext_data[3]];
                  break;
              case 5:
                  sf[0] = at9_band_ext_scales_m0[2][0][c->band_ext_data[0]];
                  sf[1] = at9_band_ext_scales_m0[2][1][c->band_ext_data[1]];
                  sf[2] = at9_band_ext_scales_m0[2][2][c->band_ext_data[1]];
                  break;
              }
  
              sf[l] = at9_scalefactor_c[c->scalefactors[g_units[0]]];
  
              fill_with_noise(s, c, n_start, n_cnt);
              scale_band_ext_coeffs(c, sf, g_units[0], g_units[3]);
              break;
          }
          case 1: {
              float sf[6];
              for (int i = g_units[0]; i < g_units[3]; i++)
                  sf[i - g_units[0]] = at9_scalefactor_c[c->scalefactors[i]];
  
              fill_with_noise(s, c, g_bins[0], g_bins[3] - g_bins[0]);
              scale_band_ext_coeffs(c, sf, g_units[0], g_units[3]);
              break;
          }
          case 2: {
              const float g_sf[2] = {
                  at9_band_ext_scales_m2[c->band_ext_data[0]],
                  at9_band_ext_scales_m2[c->band_ext_data[1]],
              };
  
              for (int i = 0; i < 2; i++)
                  for (int j = g_bins[i + 0]; j < g_bins[i + 1]; j++)
                      c->coeffs[j] *= g_sf[i];
              break;
          }
          case 3: {
              float scale = at9_band_ext_scales_m3[c->band_ext_data[0]][0];
              float rate  = at9_band_ext_scales_m3[c->band_ext_data[1]][1];
              rate = pow(2, rate);
              for (int i = g_bins[0]; i < g_bins[3]; i++) {
                  scale *= rate;
                  c->coeffs[i] *= scale;
              }
              break;
          }
          case 4: {
              const float m = at9_band_ext_scales_m4[c->band_ext_data[0]];
              const float g_sf[3] = { 0.7079468f*m, 0.5011902f*m, 0.3548279f*m };
  
              for (int i = 0; i < 3; i++)
                  for (int j = g_bins[i + 0]; j < g_bins[i + 1]; j++)
                      c->coeffs[j] *= g_sf[i];
              break;
          }
          }
      }
  }
  
  static int atrac9_decode_block(ATRAC9Context *s, GetBitContext *gb,
                                 ATRAC9BlockData *b, AVFrame *frame,
                                 int frame_idx, int block_idx)
  {
      const int first_in_pkt = !get_bits1(gb);
      const int reuse_params =  get_bits1(gb);
      const int stereo = s->block_config->type[block_idx] == ATRAC9_BLOCK_TYPE_CPE;
  
      if (s->block_config->type[block_idx] == ATRAC9_BLOCK_TYPE_LFE) {
          ATRAC9ChannelData *c = &b->channel[0];
          const int precision = reuse_params ? 8 : 4;
          c->q_unit_cnt = b->q_unit_cnt = 2;
  
          memset(c->scalefactors, 0, sizeof(c->scalefactors));
          memset(c->q_coeffs_fine, 0, sizeof(c->q_coeffs_fine));
          memset(c->q_coeffs_coarse, 0, sizeof(c->q_coeffs_coarse));
  
          for (int i = 0; i < b->q_unit_cnt; i++) {
              c->scalefactors[i] = get_bits(gb, 5);
              c->precision_coarse[i] = precision;
              c->precision_fine[i] = 0;
          }
  
          for (int i = 0; i < c->q_unit_cnt; i++) {
              const int start = at9_q_unit_to_coeff_idx[i + 0];
              const int end   = at9_q_unit_to_coeff_idx[i + 1];
              for (int j = start; j < end; j++)
                  c->q_coeffs_coarse[j] = get_bits(gb, c->precision_coarse[i] + 1);
          }
  
          dequantize        (s, b, c);
          apply_scalefactors(s, b, 0);
  
          goto imdct;
      }
  
      if (first_in_pkt && reuse_params) {
          av_log(s->avctx, AV_LOG_ERROR, "Invalid block flags!\n");
          return AVERROR_INVALIDDATA;
      }
  
      /* Band parameters */
      if (!reuse_params) {
          int stereo_band, ext_band;
          const int min_band_count = s->samplerate_idx > 7 ? 1 : 3;
          b->reuseable = 0;
          b->band_count = get_bits(gb, 4) + min_band_count;
          b->q_unit_cnt = at9_tab_band_q_unit_map[b->band_count];
  
          b->band_ext_q_unit = b->stereo_q_unit = b->q_unit_cnt;
  
          if (b->band_count > at9_tab_sri_max_bands[s->samplerate_idx]) {
              av_log(s->avctx, AV_LOG_ERROR, "Invalid band count %i!\n",
                     b->band_count);
              return AVERROR_INVALIDDATA;
          }
  
          if (stereo) {
              stereo_band = get_bits(gb, 4) + min_band_count;
              if (stereo_band > b->band_count) {
                  av_log(s->avctx, AV_LOG_ERROR, "Invalid stereo band %i!\n",
                         stereo_band);
                  return AVERROR_INVALIDDATA;
              }
              b->stereo_q_unit = at9_tab_band_q_unit_map[stereo_band];
          }
  
          b->has_band_ext = get_bits1(gb);
          if (b->has_band_ext) {
              ext_band = get_bits(gb, 4) + min_band_count;
              if (ext_band < b->band_count) {
                  av_log(s->avctx, AV_LOG_ERROR, "Invalid extension band %i!\n",
                         ext_band);
                  return AVERROR_INVALIDDATA;
              }
              b->band_ext_q_unit = at9_tab_band_q_unit_map[ext_band];
          }
          b->reuseable = 1;
      }
      if (!b->reuseable) {
          av_log(s->avctx, AV_LOG_ERROR, "invalid block reused!\n");
          return AVERROR_INVALIDDATA;
      }
  
      /* Calculate bit alloc gradient */
      if (parse_gradient(s, b, gb))
          return AVERROR_INVALIDDATA;
  
      /* IS data */
      b->cpe_base_channel = 0;
      if (stereo) {
          b->cpe_base_channel = get_bits1(gb);
          if (get_bits1(gb)) {
              for (int i = b->stereo_q_unit; i < b->q_unit_cnt; i++)
                  b->is_signs[i] = 1 - 2*get_bits1(gb);
          } else {
              for (int i = 0; i < FF_ARRAY_ELEMS(b->is_signs); i++)
                  b->is_signs[i] = 1;
          }
      }
  
      /* Band extension */
      if (parse_band_ext(s, b, gb, stereo))
          return AVERROR_INVALIDDATA;
  
      /* Scalefactors */
      for (int i = 0; i <= stereo; i++) {
          ATRAC9ChannelData *c = &b->channel[i];
          c->q_unit_cnt = i == b->cpe_base_channel ? b->q_unit_cnt :
                                                     b->stereo_q_unit;
          if (read_scalefactors(s, b, c, gb, i, first_in_pkt))
              return AVERROR_INVALIDDATA;
  
          calc_precision    (s, b, c);
          calc_codebook_idx (s, b, c);
          read_coeffs_coarse(s, b, c, gb);
          read_coeffs_fine  (s, b, c, gb);
          dequantize        (s, b, c);
      }
  
      b->q_unit_cnt_prev = b->has_band_ext ? b->band_ext_q_unit : b->q_unit_cnt;
  
      apply_intensity_stereo(s, b, stereo);
      apply_scalefactors    (s, b, stereo);
  
      if (b->has_band_ext && b->has_band_ext_data)
          apply_band_extension  (s, b, stereo);
  
  imdct:
      for (int i = 0; i <= stereo; i++) {
          ATRAC9ChannelData *c = &b->channel[i];
          const int dst_idx = s->block_config->plane_map[block_idx][i];
          const int wsize = 1 << s->frame_log2;
          const ptrdiff_t offset = wsize*frame_idx*sizeof(float);
          float *dst = (float *)(frame->extended_data[dst_idx] + offset);
  
          s->imdct.imdct_half(&s->imdct, s->temp, c->coeffs);
          s->fdsp->vector_fmul_window(dst, c->prev_win, s->temp,
                                      s->imdct_win, wsize >> 1);
          memcpy(c->prev_win, s->temp + (wsize >> 1), sizeof(float)*wsize >> 1);
      }
  
      return 0;
  }
  
  static int atrac9_decode_frame(AVCodecContext *avctx, void *data,
                                 int *got_frame_ptr, AVPacket *avpkt)
  {
      int ret;
      GetBitContext gb;
      AVFrame *frame = data;
      ATRAC9Context *s = avctx->priv_data;
      const int frames = FFMIN(avpkt->size / s->avg_frame_size, s->frame_count);
  
      frame->nb_samples = (1 << s->frame_log2) * frames;
      ret = ff_get_buffer(avctx, frame, 0);
      if (ret < 0)
          return ret;
  
      init_get_bits8(&gb, avpkt->data, avpkt->size);
  
      for (int i = 0; i < frames; i++) {
          for (int j = 0; j < s->block_config->count; j++) {
              ret = atrac9_decode_block(s, &gb, &s->block[j], frame, i, j);
              if (ret)
                  return ret;
              align_get_bits(&gb);
          }
      }
  
      *got_frame_ptr = 1;
  
      return avctx->block_align;
  }
  
  static void atrac9_decode_flush(AVCodecContext *avctx)
  {
      ATRAC9Context *s = avctx->priv_data;
  
      for (int j = 0; j < s->block_config->count; j++) {
          ATRAC9BlockData *b = &s->block[j];
          const int stereo = s->block_config->type[j] == ATRAC9_BLOCK_TYPE_CPE;
          for (int i = 0; i <= stereo; i++) {
              ATRAC9ChannelData *c = &b->channel[i];
              memset(c->prev_win, 0, sizeof(c->prev_win));
          }
      }
  }
  
  static av_cold int atrac9_decode_close(AVCodecContext *avctx)
  {
      ATRAC9Context *s = avctx->priv_data;
  
      for (int i = 1; i < 7; i++)
          ff_free_vlc(&s->sf_vlc[0][i]);
      for (int i = 2; i < 6; i++)
          ff_free_vlc(&s->sf_vlc[1][i]);
      for (int i = 0; i < 2; i++)
          for (int j = 0; j < 8; j++)
              for (int k = 0; k < 4; k++)
                  ff_free_vlc(&s->coeff_vlc[i][j][k]);
  
      ff_mdct_end(&s->imdct);
      av_free(s->fdsp);
  
      return 0;
  }
  
  static av_cold int atrac9_decode_init(AVCodecContext *avctx)
  {
      GetBitContext gb;
      ATRAC9Context *s = avctx->priv_data;
      int version, block_config_idx, superframe_idx, alloc_c_len;
  
      s->avctx = avctx;
  
      av_lfg_init(&s->lfg, 0xFBADF00D);
  
      if (avctx->block_align <= 0) {
          av_log(avctx, AV_LOG_ERROR, "Invalid block align\n");
          return AVERROR_INVALIDDATA;
      }
  
      if (avctx->extradata_size != 12) {
          av_log(avctx, AV_LOG_ERROR, "Invalid extradata length!\n");
          return AVERROR_INVALIDDATA;
      }
  
      version = AV_RL32(avctx->extradata);
      if (version > 2) {
          av_log(avctx, AV_LOG_ERROR, "Unsupported version (%i)!\n", version);
          return AVERROR_INVALIDDATA;
      }
  
      init_get_bits8(&gb, avctx->extradata + 4, avctx->extradata_size);
  
      if (get_bits(&gb, 8) != 0xFE) {
          av_log(avctx, AV_LOG_ERROR, "Incorrect magic byte!\n");
          return AVERROR_INVALIDDATA;
      }
  
      s->samplerate_idx = get_bits(&gb, 4);
      avctx->sample_rate = at9_tab_samplerates[s->samplerate_idx];
  
      block_config_idx = get_bits(&gb, 3);
      if (block_config_idx > 5) {
          av_log(avctx, AV_LOG_ERROR, "Incorrect block config!\n");
          return AVERROR_INVALIDDATA;
      }
      s->block_config = &at9_block_layout[block_config_idx];
  
      avctx->channel_layout = s->block_config->channel_layout;
      avctx->channels       = av_get_channel_layout_nb_channels(avctx->channel_layout);
      avctx->sample_fmt     = AV_SAMPLE_FMT_FLTP;
  
      if (get_bits1(&gb)) {
          av_log(avctx, AV_LOG_ERROR, "Incorrect verification bit!\n");
          return AVERROR_INVALIDDATA;
      }
  
      /* Average frame size in bytes */
      s->avg_frame_size = get_bits(&gb, 11) + 1;
  
      superframe_idx = get_bits(&gb, 2);
      if (superframe_idx & 1) {
          av_log(avctx, AV_LOG_ERROR, "Invalid superframe index!\n");
          return AVERROR_INVALIDDATA;
      }
  
      s->frame_count = 1 << superframe_idx;
      s->frame_log2  = at9_tab_sri_frame_log2[s->samplerate_idx];
  
      if (ff_mdct_init(&s->imdct, s->frame_log2 + 1, 1, 1.0f / 32768.0f))
          return AVERROR(ENOMEM);
  
      s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
      if (!s->fdsp)
          return AVERROR(ENOMEM);
  
      /* iMDCT window */
      for (int i = 0; i < (1 << s->frame_log2); i++) {
          const int   len  = 1 << s->frame_log2;
          const float sidx = (      i + 0.5f) / len;
          const float eidx = (len - i - 0.5f) / len;
          const float s_c  = sinf(sidx*M_PI - M_PI_2)*0.5f + 0.5f;
          const float e_c  = sinf(eidx*M_PI - M_PI_2)*0.5f + 0.5f;
          s->imdct_win[i]  = s_c / ((s_c * s_c) + (e_c * e_c));
      }
  
      /* Allocation curve */
      alloc_c_len = FF_ARRAY_ELEMS(at9_tab_b_dist);
      for (int i = 1; i <= alloc_c_len; i++)
          for (int j = 0; j < i; j++)
              s->alloc_curve[i - 1][j] = at9_tab_b_dist[(j * alloc_c_len) / i];
  
      /* Unsigned scalefactor VLCs */
      for (int i = 1; i < 7; i++) {
          const HuffmanCodebook *hf = &at9_huffman_sf_unsigned[i];
  
          init_vlc(&s->sf_vlc[0][i], 9, hf->size, hf->bits, 1, 1, hf->codes,
                   2, 2, 0);
      }
  
      /* Signed scalefactor VLCs */
      for (int i = 2; i < 6; i++) {
          const HuffmanCodebook *hf = &at9_huffman_sf_signed[i];
  
          int nums = hf->size;
          int16_t sym[32];
          for (int j = 0; j < nums; j++)
              sym[j] = sign_extend(j, hf->value_bits);
  
          ff_init_vlc_sparse(&s->sf_vlc[1][i], 9, hf->size, hf->bits, 1, 1,
                             hf->codes, 2, 2, sym, sizeof(*sym), sizeof(*sym), 0);
      }
  
      /* Coefficient VLCs */
      for (int i = 0; i < 2; i++) {
          for (int j = 0; j < 8; j++) {
              for (int k = 0; k < 4; k++) {
                  const HuffmanCodebook *hf = &at9_huffman_coeffs[i][j][k];
                  init_vlc(&s->coeff_vlc[i][j][k], 9, hf->size, hf->bits, 1, 1,
                           hf->codes, 2, 2, 0);
              }
          }
      }
  
      return 0;
  }
  
  AVCodec ff_atrac9_decoder = {
      .name           = "atrac9",
      .long_name      = NULL_IF_CONFIG_SMALL("ATRAC9 (Adaptive TRansform Acoustic Coding 9)"),
      .type           = AVMEDIA_TYPE_AUDIO,
      .id             = AV_CODEC_ID_ATRAC9,
      .priv_data_size = sizeof(ATRAC9Context),
      .init           = atrac9_decode_init,
      .close          = atrac9_decode_close,
      .decode         = atrac9_decode_frame,
      .flush          = atrac9_decode_flush,
      .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
      .capabilities   = AV_CODEC_CAP_SUBFRAMES | AV_CODEC_CAP_DR1,
  };
  