text: /*
   * TwinVQ decoder
   * Copyright (c) 2009 Vitor Sessak
   *
   * 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 "avcodec.h"
  #include "get_bits.h"
  #include "dsputil.h"
  #include "fft.h"
  #include "lsp.h"
  #include "sinewin.h"
  
  #include <math.h>
  #include <stdint.h>
  
  #include "twinvq_data.h"
  
  enum FrameType {
      FT_SHORT = 0,  ///< Short frame  (divided in n   sub-blocks)
      FT_MEDIUM,     ///< Medium frame (divided in m<n sub-blocks)
      FT_LONG,       ///< Long frame   (single sub-block + PPC)
      FT_PPC,        ///< Periodic Peak Component (part of the long frame)
  };
  
  /**
   * Parameters and tables that are different for each frame type
   */
  struct FrameMode {
      uint8_t         sub;      ///< Number subblocks in each frame
      const uint16_t *bark_tab;
  
      /** number of distinct bark scale envelope values */
      uint8_t         bark_env_size;
  
      const int16_t  *bark_cb;    ///< codebook for the bark scale envelope (BSE)
      uint8_t         bark_n_coef;///< number of BSE CB coefficients to read
      uint8_t         bark_n_bit; ///< number of bits of the BSE coefs
  
      //@{
      /** main codebooks for spectrum data */
      const int16_t    *cb0;
      const int16_t    *cb1;
      //@}
  
      uint8_t         cb_len_read; ///< number of spectrum coefficients to read
  };
  
  /**
   * Parameters and tables that are different for every combination of
   * bitrate/sample rate
   */
  typedef struct {
      struct FrameMode fmode[3]; ///< frame type-dependant parameters
  
      uint16_t     size;        ///< frame size in samples
      uint8_t      n_lsp;       ///< number of lsp coefficients
      const float *lspcodebook;
  
      /* number of bits of the different LSP CB coefficients */
      uint8_t      lsp_bit0;
      uint8_t      lsp_bit1;
      uint8_t      lsp_bit2;
  
      uint8_t      lsp_split;      ///< number of CB entries for the LSP decoding
      const int16_t *ppc_shape_cb; ///< PPC shape CB
  
      /** number of the bits for the PPC period value */
      uint8_t      ppc_period_bit;
  
      uint8_t      ppc_shape_bit;  ///< number of bits of the PPC shape CB coeffs
      uint8_t      ppc_shape_len;  ///< size of PPC shape CB
      uint8_t      pgain_bit;      ///< bits for PPC gain
  
      /** constant for peak period to peak width conversion */
      uint16_t     peak_per2wid;
  } ModeTab;
  
  static const ModeTab mode_08_08 = {
      {
          { 8, bark_tab_s08_64,  10, tab.fcb08s  , 1, 5, tab.cb0808s0, tab.cb0808s1, 18},
          { 2, bark_tab_m08_256, 20, tab.fcb08m  , 2, 5, tab.cb0808m0, tab.cb0808m1, 16},
          { 1, bark_tab_l08_512, 30, tab.fcb08l  , 3, 6, tab.cb0808l0, tab.cb0808l1, 17}
      },
      512 , 12, tab.lsp08,   1, 5, 3, 3, tab.shape08  , 8, 28, 20, 6, 40
  };
  
  static const ModeTab mode_11_08 = {
      {
          { 8, bark_tab_s11_64,  10, tab.fcb11s  , 1, 5, tab.cb1108s0, tab.cb1108s1, 29},
          { 2, bark_tab_m11_256, 20, tab.fcb11m  , 2, 5, tab.cb1108m0, tab.cb1108m1, 24},
          { 1, bark_tab_l11_512, 30, tab.fcb11l  , 3, 6, tab.cb1108l0, tab.cb1108l1, 27}
      },
      512 , 16, tab.lsp11,   1, 6, 4, 3, tab.shape11  , 9, 36, 30, 7, 90
  };
  
  static const ModeTab mode_11_10 = {
      {
          { 8, bark_tab_s11_64,  10, tab.fcb11s  , 1, 5, tab.cb1110s0, tab.cb1110s1, 21},
          { 2, bark_tab_m11_256, 20, tab.fcb11m  , 2, 5, tab.cb1110m0, tab.cb1110m1, 18},
          { 1, bark_tab_l11_512, 30, tab.fcb11l  , 3, 6, tab.cb1110l0, tab.cb1110l1, 20}
      },
      512 , 16, tab.lsp11,   1, 6, 4, 3, tab.shape11  , 9, 36, 30, 7, 90
  };
  
  static const ModeTab mode_16_16 = {
      {
          { 8, bark_tab_s16_128, 10, tab.fcb16s  , 1, 5, tab.cb1616s0, tab.cb1616s1, 16},
          { 2, bark_tab_m16_512, 20, tab.fcb16m  , 2, 5, tab.cb1616m0, tab.cb1616m1, 15},
          { 1, bark_tab_l16_1024,30, tab.fcb16l  , 3, 6, tab.cb1616l0, tab.cb1616l1, 16}
      },
      1024, 16, tab.lsp16,   1, 6, 4, 3, tab.shape16  , 9, 56, 60, 7, 180
  };
  
  static const ModeTab mode_22_20 = {
      {
          { 8, bark_tab_s22_128, 10, tab.fcb22s_1, 1, 6, tab.cb2220s0, tab.cb2220s1, 18},
          { 2, bark_tab_m22_512, 20, tab.fcb22m_1, 2, 6, tab.cb2220m0, tab.cb2220m1, 17},
          { 1, bark_tab_l22_1024,32, tab.fcb22l_1, 4, 6, tab.cb2220l0, tab.cb2220l1, 18}
      },
      1024, 16, tab.lsp22_1, 1, 6, 4, 3, tab.shape22_1, 9, 56, 36, 7, 144
  };
  
  static const ModeTab mode_22_24 = {
      {
          { 8, bark_tab_s22_128, 10, tab.fcb22s_1, 1, 6, tab.cb2224s0, tab.cb2224s1, 15},
          { 2, bark_tab_m22_512, 20, tab.fcb22m_1, 2, 6, tab.cb2224m0, tab.cb2224m1, 14},
          { 1, bark_tab_l22_1024,32, tab.fcb22l_1, 4, 6, tab.cb2224l0, tab.cb2224l1, 15}
      },
      1024, 16, tab.lsp22_1, 1, 6, 4, 3, tab.shape22_1, 9, 56, 36, 7, 144
  };
  
  static const ModeTab mode_22_32 = {
      {
          { 4, bark_tab_s22_128, 10, tab.fcb22s_2, 1, 6, tab.cb2232s0, tab.cb2232s1, 11},
          { 2, bark_tab_m22_256, 20, tab.fcb22m_2, 2, 6, tab.cb2232m0, tab.cb2232m1, 11},
          { 1, bark_tab_l22_512, 32, tab.fcb22l_2, 4, 6, tab.cb2232l0, tab.cb2232l1, 12}
      },
      512 , 16, tab.lsp22_2, 1, 6, 4, 4, tab.shape22_2, 9, 56, 36, 7, 72
  };
  
  static const ModeTab mode_44_40 = {
      {
          {16, bark_tab_s44_128, 10, tab.fcb44s  , 1, 6, tab.cb4440s0, tab.cb4440s1, 18},
          { 4, bark_tab_m44_512, 20, tab.fcb44m  , 2, 6, tab.cb4440m0, tab.cb4440m1, 17},
          { 1, bark_tab_l44_2048,40, tab.fcb44l  , 4, 6, tab.cb4440l0, tab.cb4440l1, 17}
      },
      2048, 20, tab.lsp44,   1, 6, 4, 4, tab.shape44  , 9, 84, 54, 7, 432
  };
  
  static const ModeTab mode_44_48 = {
      {
          {16, bark_tab_s44_128, 10, tab.fcb44s  , 1, 6, tab.cb4448s0, tab.cb4448s1, 15},
          { 4, bark_tab_m44_512, 20, tab.fcb44m  , 2, 6, tab.cb4448m0, tab.cb4448m1, 14},
          { 1, bark_tab_l44_2048,40, tab.fcb44l  , 4, 6, tab.cb4448l0, tab.cb4448l1, 14}
      },
      2048, 20, tab.lsp44,   1, 6, 4, 4, tab.shape44  , 9, 84, 54, 7, 432
  };
  
  typedef struct TwinContext {
      AVCodecContext *avctx;
      AVFrame frame;
      DSPContext      dsp;
      FFTContext mdct_ctx[3];
  
      const ModeTab *mtab;
  
      // history
      float lsp_hist[2][20];           ///< LSP coefficients of the last frame
      float bark_hist[3][2][40];       ///< BSE coefficients of last frame
  
      // bitstream parameters
      int16_t permut[4][4096];
      uint8_t length[4][2];            ///< main codebook stride
      uint8_t length_change[4];
      uint8_t bits_main_spec[2][4][2]; ///< bits for the main codebook
      int bits_main_spec_change[4];
      int n_div[4];
  
      float *spectrum;
      float *curr_frame;               ///< non-interleaved output
      float *prev_frame;               ///< non-interleaved previous frame
      int last_block_pos[2];
      int discarded_packets;
  
      float *cos_tabs[3];
  
      // scratch buffers
      float *tmp_buf;
  } TwinContext;
  
  #define PPC_SHAPE_CB_SIZE 64
  #define PPC_SHAPE_LEN_MAX 60
  #define SUB_AMP_MAX       4500.0
  #define MULAW_MU          100.0
  #define GAIN_BITS         8
  #define AMP_MAX           13000.0
  #define SUB_GAIN_BITS     5
  #define WINDOW_TYPE_BITS  4
  #define PGAIN_MU          200
  #define LSP_COEFS_MAX     20
  #define LSP_SPLIT_MAX     4
  #define CHANNELS_MAX      2
  #define SUBBLOCKS_MAX     16
  #define BARK_N_COEF_MAX   4
  
  /** @note not speed critical, hence not optimized */
  static void memset_float(float *buf, float val, int size)
  {
      while (size--)
          *buf++ = val;
  }
  
  /**
   * Evaluate a single LPC amplitude spectrum envelope coefficient from the line
   * spectrum pairs.
   *
   * @param lsp a vector of the cosinus of the LSP values
   * @param cos_val cos(PI*i/N) where i is the index of the LPC amplitude
   * @param order the order of the LSP (and the size of the *lsp buffer). Must
   *        be a multiple of four.
   * @return the LPC value
   *
   * @todo reuse code from Vorbis decoder: vorbis_floor0_decode
   */
  static float eval_lpc_spectrum(const float *lsp, float cos_val, int order)
  {
      int j;
      float p = 0.5f;
      float q = 0.5f;
      float two_cos_w = 2.0f*cos_val;
  
      for (j = 0; j + 1 < order; j += 2*2) {
          // Unroll the loop once since order is a multiple of four
          q *= lsp[j  ] - two_cos_w;
          p *= lsp[j+1] - two_cos_w;
  
          q *= lsp[j+2] - two_cos_w;
          p *= lsp[j+3] - two_cos_w;
      }
  
      p *= p * (2.0f - two_cos_w);
      q *= q * (2.0f + two_cos_w);
  
      return 0.5 / (p + q);
  }
  
  /**
   * Evaluate the LPC amplitude spectrum envelope from the line spectrum pairs.
   */
  static void eval_lpcenv(TwinContext *tctx, const float *cos_vals, float *lpc)
  {
      int i;
      const ModeTab *mtab = tctx->mtab;
      int size_s = mtab->size / mtab->fmode[FT_SHORT].sub;
  
      for (i = 0; i < size_s/2; i++) {
          float cos_i = tctx->cos_tabs[0][i];
          lpc[i]          = eval_lpc_spectrum(cos_vals,  cos_i, mtab->n_lsp);
          lpc[size_s-i-1] = eval_lpc_spectrum(cos_vals, -cos_i, mtab->n_lsp);
      }
  }
  
  static void interpolate(float *out, float v1, float v2, int size)
  {
      int i;
      float step = (v1 - v2)/(size + 1);
  
      for (i = 0; i < size; i++) {
          v2 += step;
          out[i] = v2;
      }
  }
  
  static inline float get_cos(int idx, int part, const float *cos_tab, int size)
  {
      return part ? -cos_tab[size - idx - 1] :
                     cos_tab[       idx    ];
  }
  
  /**
   * Evaluate the LPC amplitude spectrum envelope from the line spectrum pairs.
   * Probably for speed reasons, the coefficients are evaluated as
   * siiiibiiiisiiiibiiiisiiiibiiiisiiiibiiiis ...
   * where s is an evaluated value, i is a value interpolated from the others
   * and b might be either calculated or interpolated, depending on an
   * unexplained condition.
   *
   * @param step the size of a block "siiiibiiii"
   * @param in the cosinus of the LSP data
   * @param part is 0 for 0...PI (positive cossinus values) and 1 for PI...2PI
            (negative cossinus values)
   * @param size the size of the whole output
   */
  static inline void eval_lpcenv_or_interp(TwinContext *tctx,
                                           enum FrameType ftype,
                                           float *out, const float *in,
                                           int size, int step, int part)
  {
      int i;
      const ModeTab *mtab = tctx->mtab;
      const float *cos_tab = tctx->cos_tabs[ftype];
  
      // Fill the 's'
      for (i = 0; i < size; i += step)
          out[i] =
              eval_lpc_spectrum(in,
                                get_cos(i, part, cos_tab, size),
                                mtab->n_lsp);
  
      // Fill the 'iiiibiiii'
      for (i = step; i <= size - 2*step; i += step) {
          if (out[i + step] + out[i - step] >  1.95*out[i] ||
              out[i + step]                 >=  out[i - step]) {
              interpolate(out + i - step + 1, out[i], out[i-step], step - 1);
          } else {
              out[i - step/2] =
                  eval_lpc_spectrum(in,
                                    get_cos(i-step/2, part, cos_tab, size),
                                    mtab->n_lsp);
              interpolate(out + i - step   + 1, out[i-step/2], out[i-step  ], step/2 - 1);
              interpolate(out + i - step/2 + 1, out[i       ], out[i-step/2], step/2 - 1);
          }
      }
  
      interpolate(out + size - 2*step + 1, out[size-step], out[size - 2*step], step - 1);
  }
  
  static void eval_lpcenv_2parts(TwinContext *tctx, enum FrameType ftype,
                                 const float *buf, float *lpc,
                                 int size, int step)
  {
      eval_lpcenv_or_interp(tctx, ftype, lpc         , buf, size/2,   step, 0);
      eval_lpcenv_or_interp(tctx, ftype, lpc + size/2, buf, size/2, 2*step, 1);
  
      interpolate(lpc+size/2-step+1, lpc[size/2], lpc[size/2-step], step);
  
      memset_float(lpc + size - 2*step + 1, lpc[size - 2*step], 2*step - 1);
  }
  
  /**
   * Inverse quantization. Read CB coefficients for cb1 and cb2 from the
   * bitstream, sum the corresponding vectors and write the result to *out
   * after permutation.
   */
  static void dequant(TwinContext *tctx, GetBitContext *gb, float *out,
                      enum FrameType ftype,
                      const int16_t *cb0, const int16_t *cb1, int cb_len)
  {
      int pos = 0;
      int i, j;
  
      for (i = 0; i < tctx->n_div[ftype]; i++) {
          int tmp0, tmp1;
          int sign0 = 1;
          int sign1 = 1;
          const int16_t *tab0, *tab1;
          int length = tctx->length[ftype][i >= tctx->length_change[ftype]];
          int bitstream_second_part = (i >= tctx->bits_main_spec_change[ftype]);
  
          int bits = tctx->bits_main_spec[0][ftype][bitstream_second_part];
          if (bits == 7) {
              if (get_bits1(gb))
                  sign0 = -1;
              bits = 6;
          }
          tmp0 = get_bits(gb, bits);
  
          bits = tctx->bits_main_spec[1][ftype][bitstream_second_part];
  
          if (bits == 7) {
              if (get_bits1(gb))
                  sign1 = -1;
  
              bits = 6;
          }
          tmp1 = get_bits(gb, bits);
  
          tab0 = cb0 + tmp0*cb_len;
          tab1 = cb1 + tmp1*cb_len;
  
          for (j = 0; j < length; j++)
              out[tctx->permut[ftype][pos+j]] = sign0*tab0[j] + sign1*tab1[j];
  
          pos += length;
      }
  
  }
  
  static inline float mulawinv(float y, float clip, float mu)
  {
      y = av_clipf(y/clip, -1, 1);
      return clip * FFSIGN(y) * (exp(log(1+mu) * fabs(y)) - 1) / mu;
  }
  
  /**
   * Evaluate a*b/400 rounded to the nearest integer. When, for example,
   * a*b == 200 and the nearest integer is ill-defined, use a table to emulate
   * the following broken float-based implementation used by the binary decoder:
   *
   * @code
   * static int very_broken_op(int a, int b)
   * {
   *    static float test; // Ugh, force gcc to do the division first...
   *
   *    test = a/400.;
   *    return b * test +  0.5;
   * }
   * @endcode
   *
   * @note if this function is replaced by just ROUNDED_DIV(a*b,400.), the stddev
   * between the original file (before encoding with Yamaha encoder) and the
   * decoded output increases, which leads one to believe that the encoder expects
   * exactly this broken calculation.
   */
  static int very_broken_op(int a, int b)
  {
      int x = a*b + 200;
      int size;
      const uint8_t *rtab;
  
      if (x%400 || b%5)
          return x/400;
  
      x /= 400;
  
      size = tabs[b/5].size;
      rtab = tabs[b/5].tab;
      return x - rtab[size*av_log2(2*(x - 1)/size)+(x - 1)%size];
  }
  
  /**
   * Sum to data a periodic peak of a given period, width and shape.
   *
   * @param period the period of the peak divised by 400.0
   */
  static void add_peak(int period, int width, const float *shape,
                       float ppc_gain, float *speech, int len)
  {
      int i, j;
  
      const float *shape_end = shape + len;
      int center;
  
      // First peak centered around zero
      for (i = 0; i < width/2; i++)
          speech[i] += ppc_gain * *shape++;
  
      for (i = 1; i < ROUNDED_DIV(len,width) ; i++) {
          center = very_broken_op(period, i);
          for (j = -width/2; j < (width+1)/2; j++)
              speech[j+center] += ppc_gain * *shape++;
      }
  
      // For the last block, be careful not to go beyond the end of the buffer
      center = very_broken_op(period, i);
      for (j = -width/2; j < (width + 1)/2 && shape < shape_end; j++)
          speech[j+center] += ppc_gain * *shape++;
  }
  
  static void decode_ppc(TwinContext *tctx, int period_coef, const float *shape,
                         float ppc_gain, float *speech)
  {
      const ModeTab *mtab = tctx->mtab;
      int isampf = tctx->avctx->sample_rate/1000;
      int ibps = tctx->avctx->bit_rate/(1000 * tctx->avctx->channels);
      int min_period = ROUNDED_DIV(  40*2*mtab->size, isampf);
      int max_period = ROUNDED_DIV(6*40*2*mtab->size, isampf);
      int period_range = max_period - min_period;
  
      // This is actually the period multiplied by 400. It is just linearly coded
      // between its maximum and minimum value.
      int period = min_period +
          ROUNDED_DIV(period_coef*period_range, (1 << mtab->ppc_period_bit) - 1);
      int width;
  
      if (isampf == 22 && ibps == 32) {
          // For some unknown reason, NTT decided to code this case differently...
          width = ROUNDED_DIV((period + 800)* mtab->peak_per2wid, 400*mtab->size);
      } else
          width =             (period      )* mtab->peak_per2wid/(400*mtab->size);
  
      add_peak(period, width, shape, ppc_gain, speech, mtab->ppc_shape_len);
  }
  
  static void dec_gain(TwinContext *tctx, GetBitContext *gb, enum FrameType ftype,
                       float *out)
  {
      const ModeTab *mtab = tctx->mtab;
      int i, j;
      int sub = mtab->fmode[ftype].sub;
      float step     = AMP_MAX     / ((1 <<     GAIN_BITS) - 1);
      float sub_step = SUB_AMP_MAX / ((1 << SUB_GAIN_BITS) - 1);
  
      if (ftype == FT_LONG) {
          for (i = 0; i < tctx->avctx->channels; i++)
              out[i] = (1./(1<<13)) *
                  mulawinv(step * 0.5 + step * get_bits(gb, GAIN_BITS),
                           AMP_MAX, MULAW_MU);
      } else {
          for (i = 0; i < tctx->avctx->channels; i++) {
              float val = (1./(1<<23)) *
                  mulawinv(step * 0.5 + step * get_bits(gb, GAIN_BITS),
                           AMP_MAX, MULAW_MU);
  
              for (j = 0; j < sub; j++) {
                  out[i*sub + j] =
                      val*mulawinv(sub_step* 0.5 +
                                   sub_step* get_bits(gb, SUB_GAIN_BITS),
                                   SUB_AMP_MAX, MULAW_MU);
              }
          }
      }
  }
  
  /**
   * Rearrange the LSP coefficients so that they have a minimum distance of
   * min_dist. This function does it exactly as described in section of 3.2.4
   * of the G.729 specification (but interestingly is different from what the
   * reference decoder actually does).
   */
  static void rearrange_lsp(int order, float *lsp, float min_dist)
  {
      int i;
      float min_dist2 = min_dist * 0.5;
      for (i = 1; i < order; i++)
          if (lsp[i] - lsp[i-1] < min_dist) {
              float avg = (lsp[i] + lsp[i-1]) * 0.5;
  
              lsp[i-1] = avg - min_dist2;
              lsp[i  ] = avg + min_dist2;
          }
  }
  
  static void decode_lsp(TwinContext *tctx, int lpc_idx1, uint8_t *lpc_idx2,
                         int lpc_hist_idx, float *lsp, float *hist)
  {
      const ModeTab *mtab = tctx->mtab;
      int i, j;
  
      const float *cb  =  mtab->lspcodebook;
      const float *cb2 =  cb  + (1 << mtab->lsp_bit1)*mtab->n_lsp;
      const float *cb3 =  cb2 + (1 << mtab->lsp_bit2)*mtab->n_lsp;
  
      const int8_t funny_rounding[4] = {
          -2,
          mtab->lsp_split == 4 ? -2 : 1,
          mtab->lsp_split == 4 ? -2 : 1,
          0
      };
  
      j = 0;
      for (i = 0; i < mtab->lsp_split; i++) {
          int chunk_end = ((i + 1)*mtab->n_lsp + funny_rounding[i])/mtab->lsp_split;
          for (; j < chunk_end; j++)
              lsp[j] = cb [lpc_idx1    * mtab->n_lsp + j] +
                       cb2[lpc_idx2[i] * mtab->n_lsp + j];
      }
  
      rearrange_lsp(mtab->n_lsp, lsp, 0.0001);
  
      for (i = 0; i < mtab->n_lsp; i++) {
          float tmp1 = 1. -          cb3[lpc_hist_idx*mtab->n_lsp + i];
          float tmp2 =     hist[i] * cb3[lpc_hist_idx*mtab->n_lsp + i];
          hist[i] = lsp[i];
          lsp[i]  = lsp[i] * tmp1 + tmp2;
      }
  
      rearrange_lsp(mtab->n_lsp, lsp, 0.0001);
      rearrange_lsp(mtab->n_lsp, lsp, 0.000095);
      ff_sort_nearly_sorted_floats(lsp, mtab->n_lsp);
  }
  
  static void dec_lpc_spectrum_inv(TwinContext *tctx, float *lsp,
                                   enum FrameType ftype, float *lpc)
  {
      int i;
      int size = tctx->mtab->size / tctx->mtab->fmode[ftype].sub;
  
      for (i = 0; i < tctx->mtab->n_lsp; i++)
          lsp[i] =  2*cos(lsp[i]);
  
      switch (ftype) {
      case FT_LONG:
          eval_lpcenv_2parts(tctx, ftype, lsp, lpc, size, 8);
          break;
      case FT_MEDIUM:
          eval_lpcenv_2parts(tctx, ftype, lsp, lpc, size, 2);
          break;
      case FT_SHORT:
          eval_lpcenv(tctx, lsp, lpc);
          break;
      }
  }
  
  static void imdct_and_window(TwinContext *tctx, enum FrameType ftype, int wtype,
                              float *in, float *prev, int ch)
  {
      FFTContext *mdct = &tctx->mdct_ctx[ftype];
      const ModeTab *mtab = tctx->mtab;
      int bsize = mtab->size / mtab->fmode[ftype].sub;
      int size  = mtab->size;
      float *buf1 = tctx->tmp_buf;
      int j;
      int wsize; // Window size
      float *out = tctx->curr_frame + 2*ch*mtab->size;
      float *out2 = out;
      float *prev_buf;
      int first_wsize;
  
      static const uint8_t wtype_to_wsize[]      = {0, 0, 2, 2, 2, 1, 0, 1, 1};
      int types_sizes[] = {
          mtab->size /    mtab->fmode[FT_LONG  ].sub,
          mtab->size /    mtab->fmode[FT_MEDIUM].sub,
          mtab->size / (2*mtab->fmode[FT_SHORT ].sub),
      };
  
      wsize = types_sizes[wtype_to_wsize[wtype]];
      first_wsize = wsize;
      prev_buf = prev + (size - bsize)/2;
  
      for (j = 0; j < mtab->fmode[ftype].sub; j++) {
          int sub_wtype = ftype == FT_MEDIUM ? 8 : wtype;
  
          if (!j && wtype == 4)
              sub_wtype = 4;
          else if (j == mtab->fmode[ftype].sub-1 && wtype == 7)
              sub_wtype = 7;
  
          wsize = types_sizes[wtype_to_wsize[sub_wtype]];
  
          mdct->imdct_half(mdct, buf1 + bsize*j, in + bsize*j);
  
          tctx->dsp.vector_fmul_window(out2,
                                       prev_buf + (bsize-wsize)/2,
                                       buf1 + bsize*j,
                                       ff_sine_windows[av_log2(wsize)],
                                       wsize/2);
          out2 += wsize;
  
          memcpy(out2, buf1 + bsize*j + wsize/2, (bsize - wsize/2)*sizeof(float));
  
          out2 += ftype == FT_MEDIUM ? (bsize-wsize)/2 : bsize - wsize;
  
          prev_buf = buf1 + bsize*j + bsize/2;
      }
  
      tctx->last_block_pos[ch] = (size + first_wsize)/2;
  }
  
  static void imdct_output(TwinContext *tctx, enum FrameType ftype, int wtype,
                           float *out)
  {
      const ModeTab *mtab = tctx->mtab;
      int size1, size2;
      float *prev_buf = tctx->prev_frame + tctx->last_block_pos[0];
      int i;
  
      for (i = 0; i < tctx->avctx->channels; i++) {
          imdct_and_window(tctx, ftype, wtype,
                           tctx->spectrum + i*mtab->size,
                           prev_buf + 2*i*mtab->size,
                           i);
      }
  
      if (!out)
          return;
  
      size2 = tctx->last_block_pos[0];
      size1 = mtab->size - size2;
      if (tctx->avctx->channels == 2) {
          tctx->dsp.butterflies_float_interleave(out, prev_buf,
                                                 &prev_buf[2*mtab->size],
                                                 size1);
  
          out += 2 * size1;
  
          tctx->dsp.butterflies_float_interleave(out, tctx->curr_frame,
                                                 &tctx->curr_frame[2*mtab->size],
                                                 size2);
      } else {
          memcpy(out, prev_buf, size1 * sizeof(*out));
  
          out += size1;
  
          memcpy(out, tctx->curr_frame, size2 * sizeof(*out));
      }
  
  }
  
  static void dec_bark_env(TwinContext *tctx, const uint8_t *in, int use_hist,
                           int ch, float *out, float gain, enum FrameType ftype)
  {
      const ModeTab *mtab = tctx->mtab;
      int i,j;
      float *hist = tctx->bark_hist[ftype][ch];
      float val = ((const float []) {0.4, 0.35, 0.28})[ftype];
      int bark_n_coef  = mtab->fmode[ftype].bark_n_coef;
      int fw_cb_len = mtab->fmode[ftype].bark_env_size / bark_n_coef;
      int idx = 0;
  
      for (i = 0; i < fw_cb_len; i++)
          for (j = 0; j < bark_n_coef; j++, idx++) {
              float tmp2 =
                  mtab->fmode[ftype].bark_cb[fw_cb_len*in[j] + i] * (1./4096);
              float st = use_hist ?
                  (1. - val) * tmp2 + val*hist[idx] + 1. : tmp2 + 1.;
  
              hist[idx] = tmp2;
              if (st < -1.) st = 1.;
  
              memset_float(out, st * gain, mtab->fmode[ftype].bark_tab[idx]);
              out += mtab->fmode[ftype].bark_tab[idx];
          }
  
  }
  
  static void read_and_decode_spectrum(TwinContext *tctx, GetBitContext *gb,
                                       float *out, enum FrameType ftype)
  {
      const ModeTab *mtab = tctx->mtab;
      int channels = tctx->avctx->channels;
      int sub = mtab->fmode[ftype].sub;
      int block_size = mtab->size / sub;
      float gain[CHANNELS_MAX*SUBBLOCKS_MAX];
      float ppc_shape[PPC_SHAPE_LEN_MAX * CHANNELS_MAX * 4];
      uint8_t bark1[CHANNELS_MAX][SUBBLOCKS_MAX][BARK_N_COEF_MAX];
      uint8_t bark_use_hist[CHANNELS_MAX][SUBBLOCKS_MAX];
  
      uint8_t lpc_idx1[CHANNELS_MAX];
      uint8_t lpc_idx2[CHANNELS_MAX][LSP_SPLIT_MAX];
      uint8_t lpc_hist_idx[CHANNELS_MAX];
  
      int i, j, k;
  
      dequant(tctx, gb, out, ftype,
              mtab->fmode[ftype].cb0, mtab->fmode[ftype].cb1,
              mtab->fmode[ftype].cb_len_read);
  
      for (i = 0; i < channels; i++)
          for (j = 0; j < sub; j++)
              for (k = 0; k < mtab->fmode[ftype].bark_n_coef; k++)
                  bark1[i][j][k] =
                      get_bits(gb, mtab->fmode[ftype].bark_n_bit);
  
      for (i = 0; i < channels; i++)
          for (j = 0; j < sub; j++)
              bark_use_hist[i][j] = get_bits1(gb);
  
      dec_gain(tctx, gb, ftype, gain);
  
      for (i = 0; i < channels; i++) {
          lpc_hist_idx[i] = get_bits(gb, tctx->mtab->lsp_bit0);
          lpc_idx1    [i] = get_bits(gb, tctx->mtab->lsp_bit1);
  
          for (j = 0; j < tctx->mtab->lsp_split; j++)
              lpc_idx2[i][j] = get_bits(gb, tctx->mtab->lsp_bit2);
      }
  
      if (ftype == FT_LONG) {
          int cb_len_p = (tctx->n_div[3] + mtab->ppc_shape_len*channels - 1)/
              tctx->n_div[3];
          dequant(tctx, gb, ppc_shape, FT_PPC, mtab->ppc_shape_cb,
                  mtab->ppc_shape_cb + cb_len_p*PPC_SHAPE_CB_SIZE, cb_len_p);
      }
  
      for (i = 0; i < channels; i++) {
          float *chunk = out + mtab->size * i;
          float lsp[LSP_COEFS_MAX];
  
          for (j = 0; j < sub; j++) {
              dec_bark_env(tctx, bark1[i][j], bark_use_hist[i][j], i,
                           tctx->tmp_buf, gain[sub*i+j], ftype);
  
              tctx->dsp.vector_fmul(chunk + block_size*j, chunk + block_size*j, tctx->tmp_buf,
                                    block_size);
  
          }
  
          if (ftype == FT_LONG) {
              float pgain_step = 25000. / ((1 << mtab->pgain_bit) - 1);
              int p_coef = get_bits(gb, tctx->mtab->ppc_period_bit);
              int g_coef = get_bits(gb, tctx->mtab->pgain_bit);
              float v = 1./8192*
                  mulawinv(pgain_step*g_coef+ pgain_step/2, 25000., PGAIN_MU);
  
              decode_ppc(tctx, p_coef, ppc_shape + i*mtab->ppc_shape_len, v,
                         chunk);
          }
  
          decode_lsp(tctx, lpc_idx1[i], lpc_idx2[i], lpc_hist_idx[i], lsp,
                     tctx->lsp_hist[i]);
  
          dec_lpc_spectrum_inv(tctx, lsp, ftype, tctx->tmp_buf);
  
          for (j = 0; j < mtab->fmode[ftype].sub; j++) {
              tctx->dsp.vector_fmul(chunk, chunk, tctx->tmp_buf, block_size);
              chunk += block_size;
          }
      }
  }
  
  static int twin_decode_frame(AVCodecContext * avctx, void *data,
                               int *got_frame_ptr, AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      TwinContext *tctx = avctx->priv_data;
      GetBitContext gb;
      const ModeTab *mtab = tctx->mtab;
      float *out = NULL;
      enum FrameType ftype;
      int window_type, ret;
      static const enum FrameType wtype_to_ftype_table[] = {
          FT_LONG,   FT_LONG, FT_SHORT, FT_LONG,
          FT_MEDIUM, FT_LONG, FT_LONG,  FT_MEDIUM, FT_MEDIUM
      };
  
      if (buf_size*8 < avctx->bit_rate*mtab->size/avctx->sample_rate + 8) {
          av_log(avctx, AV_LOG_ERROR,
                 "Frame too small (%d bytes). Truncated file?\n", buf_size);
          return AVERROR(EINVAL);
      }
  
      /* get output buffer */
      if (tctx->discarded_packets >= 2) {
          tctx->frame.nb_samples = mtab->size;
          if ((ret = avctx->get_buffer(avctx, &tctx->frame)) < 0) {
              av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
              return ret;
          }
          out = (float *)tctx->frame.data[0];
      }
  
      init_get_bits(&gb, buf, buf_size * 8);
      skip_bits(&gb, get_bits(&gb, 8));
      window_type = get_bits(&gb, WINDOW_TYPE_BITS);
  
      if (window_type > 8) {
          av_log(avctx, AV_LOG_ERROR, "Invalid window type, broken sample?\n");
          return -1;
      }
  
      ftype = wtype_to_ftype_table[window_type];
  
      read_and_decode_spectrum(tctx, &gb, tctx->spectrum, ftype);
  
      imdct_output(tctx, ftype, window_type, out);
  
      FFSWAP(float*, tctx->curr_frame, tctx->prev_frame);
  
      if (tctx->discarded_packets < 2) {
          tctx->discarded_packets++;
          *got_frame_ptr = 0;
          return buf_size;
      }
  
      *got_frame_ptr   = 1;
      *(AVFrame *)data = tctx->frame;
  
      return buf_size;
  }
  
  /**
   * Init IMDCT and windowing tables
   */
  static av_cold int init_mdct_win(TwinContext *tctx)
  {
      int i, j, ret;
      const ModeTab *mtab = tctx->mtab;
      int size_s = mtab->size / mtab->fmode[FT_SHORT].sub;
      int size_m = mtab->size / mtab->fmode[FT_MEDIUM].sub;
      int channels = tctx->avctx->channels;
      float norm = channels == 1 ? 2. : 1.;
  
      for (i = 0; i < 3; i++) {
          int bsize = tctx->mtab->size/tctx->mtab->fmode[i].sub;
          if ((ret = ff_mdct_init(&tctx->mdct_ctx[i], av_log2(bsize) + 1, 1,
                                  -sqrt(norm/bsize) / (1<<15))))
              return ret;
      }
  
      FF_ALLOC_OR_GOTO(tctx->avctx, tctx->tmp_buf,
                       mtab->size * sizeof(*tctx->tmp_buf), alloc_fail);
  
      FF_ALLOC_OR_GOTO(tctx->avctx, tctx->spectrum,
                       2 * mtab->size * channels * sizeof(*tctx->spectrum),
                       alloc_fail);
      FF_ALLOC_OR_GOTO(tctx->avctx, tctx->curr_frame,
                       2 * mtab->size * channels * sizeof(*tctx->curr_frame),
                       alloc_fail);
      FF_ALLOC_OR_GOTO(tctx->avctx, tctx->prev_frame,
                       2 * mtab->size * channels * sizeof(*tctx->prev_frame),
                       alloc_fail);
  
      for (i = 0; i < 3; i++) {
          int m = 4*mtab->size/mtab->fmode[i].sub;
          double freq = 2*M_PI/m;
          FF_ALLOC_OR_GOTO(tctx->avctx, tctx->cos_tabs[i],
                           (m / 4) * sizeof(*tctx->cos_tabs[i]), alloc_fail);
  
          for (j = 0; j <= m/8; j++)
              tctx->cos_tabs[i][j] = cos((2*j + 1)*freq);
          for (j = 1; j <  m/8; j++)
              tctx->cos_tabs[i][m/4-j] = tctx->cos_tabs[i][j];
      }
  
  
      ff_init_ff_sine_windows(av_log2(size_m));
      ff_init_ff_sine_windows(av_log2(size_s/2));
      ff_init_ff_sine_windows(av_log2(mtab->size));
  
      return 0;
  alloc_fail:
      return AVERROR(ENOMEM);
  }
  
  /**
   * Interpret the data as if it were a num_blocks x line_len[0] matrix and for
   * each line do a cyclic permutation, i.e.
   * abcdefghijklm -> defghijklmabc
   * where the amount to be shifted is evaluated depending on the column.
   */
  static void permutate_in_line(int16_t *tab, int num_vect, int num_blocks,
                                int block_size,
                                const uint8_t line_len[2], int length_div,
                                enum FrameType ftype)
  
  {
      int i,j;
  
      for (i = 0; i < line_len[0]; i++) {
          int shift;
  
          if (num_blocks == 1 ||
              (ftype == FT_LONG && num_vect % num_blocks) ||
              (ftype != FT_LONG && num_vect & 1         ) ||
              i == line_len[1]) {
              shift = 0;
          } else if (ftype == FT_LONG) {
              shift = i;
          } else
              shift = i*i;
  
          for (j = 0; j < num_vect && (j+num_vect*i < block_size*num_blocks); j++)
              tab[i*num_vect+j] = i*num_vect + (j + shift) % num_vect;
      }
  }
  
  /**
   * Interpret the input data as in the following table:
   *
   * @verbatim
   *
   * abcdefgh
   * ijklmnop
   * qrstuvw
   * x123456
   *
   * @endverbatim
   *
   * and transpose it, giving the output
   * aiqxbjr1cks2dlt3emu4fvn5gow6hp
   */
  static void transpose_perm(int16_t *out, int16_t *in, int num_vect,
                             const uint8_t line_len[2], int length_div)
  {
      int i,j;
      int cont= 0;
      for (i = 0; i < num_vect; i++)
          for (j = 0; j < line_len[i >= length_div]; j++)
              out[cont++] = in[j*num_vect + i];
  }
  
  static void linear_perm(int16_t *out, int16_t *in, int n_blocks, int size)
  {
      int block_size = size/n_blocks;
      int i;
  
      for (i = 0; i < size; i++)
          out[i] = block_size * (in[i] % n_blocks) + in[i] / n_blocks;
  }
  
  static av_cold void construct_perm_table(TwinContext *tctx,enum FrameType ftype)
  {
      int block_size;
      const ModeTab *mtab = tctx->mtab;
      int size;
      int16_t *tmp_perm = (int16_t *) tctx->tmp_buf;
  
      if (ftype == FT_PPC) {
          size  = tctx->avctx->channels;
          block_size = mtab->ppc_shape_len;
      } else {
          size       = tctx->avctx->channels * mtab->fmode[ftype].sub;
          block_size = mtab->size / mtab->fmode[ftype].sub;
      }
  
      permutate_in_line(tmp_perm, tctx->n_div[ftype], size,
                        block_size, tctx->length[ftype],
                        tctx->length_change[ftype], ftype);
  
      transpose_perm(tctx->permut[ftype], tmp_perm, tctx->n_div[ftype],
                     tctx->length[ftype], tctx->length_change[ftype]);
  
      linear_perm(tctx->permut[ftype], tctx->permut[ftype], size,
                  size*block_size);
  }
  
  static av_cold void init_bitstream_params(TwinContext *tctx)
  {
      const ModeTab *mtab = tctx->mtab;
      int n_ch = tctx->avctx->channels;
      int total_fr_bits = tctx->avctx->bit_rate*mtab->size/
                               tctx->avctx->sample_rate;
  
      int lsp_bits_per_block = n_ch*(mtab->lsp_bit0 + mtab->lsp_bit1 +
                                     mtab->lsp_split*mtab->lsp_bit2);
  
      int ppc_bits = n_ch*(mtab->pgain_bit + mtab->ppc_shape_bit +
                           mtab->ppc_period_bit);
  
      int bsize_no_main_cb[3];
      int bse_bits[3];
      int i;
      enum FrameType frametype;
  
      for (i = 0; i < 3; i++)
          // +1 for history usage switch
          bse_bits[i] = n_ch *
              (mtab->fmode[i].bark_n_coef * mtab->fmode[i].bark_n_bit + 1);
  
      bsize_no_main_cb[2] = bse_bits[2] + lsp_bits_per_block + ppc_bits +
                            WINDOW_TYPE_BITS + n_ch*GAIN_BITS;
  
      for (i = 0; i < 2; i++)
          bsize_no_main_cb[i] =
              lsp_bits_per_block + n_ch*GAIN_BITS + WINDOW_TYPE_BITS +
              mtab->fmode[i].sub*(bse_bits[i] + n_ch*SUB_GAIN_BITS);
  
      // The remaining bits are all used for the main spectrum coefficients
      for (i = 0; i < 4; i++) {
          int bit_size;
          int vect_size;
          int rounded_up, rounded_down, num_rounded_down, num_rounded_up;
          if (i == 3) {
              bit_size  = n_ch * mtab->ppc_shape_bit;
              vect_size = n_ch * mtab->ppc_shape_len;
          } else {
              bit_size = total_fr_bits - bsize_no_main_cb[i];
              vect_size = n_ch * mtab->size;
          }
  
          tctx->n_div[i] = (bit_size + 13) / 14;
  
          rounded_up   = (bit_size + tctx->n_div[i] - 1)/tctx->n_div[i];
          rounded_down = (bit_size           )/tctx->n_div[i];
          num_rounded_down = rounded_up * tctx->n_div[i] - bit_size;
          num_rounded_up = tctx->n_div[i] - num_rounded_down;
          tctx->bits_main_spec[0][i][0] = (rounded_up   + 1)/2;
          tctx->bits_main_spec[1][i][0] = (rounded_up      )/2;
          tctx->bits_main_spec[0][i][1] = (rounded_down + 1)/2;
          tctx->bits_main_spec[1][i][1] = (rounded_down    )/2;
          tctx->bits_main_spec_change[i] = num_rounded_up;
  
          rounded_up   = (vect_size + tctx->n_div[i] - 1)/tctx->n_div[i];
          rounded_down = (vect_size                     )/tctx->n_div[i];
          num_rounded_down = rounded_up * tctx->n_div[i] - vect_size;
          num_rounded_up = tctx->n_div[i] - num_rounded_down;
          tctx->length[i][0] = rounded_up;
          tctx->length[i][1] = rounded_down;
          tctx->length_change[i] = num_rounded_up;
      }
  
      for (frametype = FT_SHORT; frametype <= FT_PPC; frametype++)
          construct_perm_table(tctx, frametype);
  }
  
  static av_cold int twin_decode_close(AVCodecContext *avctx)
  {
      TwinContext *tctx = avctx->priv_data;
      int i;
  
      for (i = 0; i < 3; i++) {
          ff_mdct_end(&tctx->mdct_ctx[i]);
          av_free(tctx->cos_tabs[i]);
      }
  
  
      av_free(tctx->curr_frame);
      av_free(tctx->spectrum);
      av_free(tctx->prev_frame);
      av_free(tctx->tmp_buf);
  
      return 0;
  }
  
  static av_cold int twin_decode_init(AVCodecContext *avctx)
  {
      int ret;
      TwinContext *tctx = avctx->priv_data;
      int isampf, ibps;
  
      tctx->avctx       = avctx;
      avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
  
      if (!avctx->extradata || avctx->extradata_size < 12) {
          av_log(avctx, AV_LOG_ERROR, "Missing or incomplete extradata\n");
          return AVERROR_INVALIDDATA;
      }
      avctx->channels = AV_RB32(avctx->extradata    ) + 1;
      avctx->bit_rate = AV_RB32(avctx->extradata + 4) * 1000;
      isampf          = AV_RB32(avctx->extradata + 8);
      switch (isampf) {
      case 44: avctx->sample_rate = 44100;         break;
      case 22: avctx->sample_rate = 22050;         break;
      case 11: avctx->sample_rate = 11025;         break;
      default: avctx->sample_rate = isampf * 1000; break;
      }
  
      if (avctx->channels > CHANNELS_MAX) {
          av_log(avctx, AV_LOG_ERROR, "Unsupported number of channels: %i\n",
                 avctx->channels);
          return -1;
      }
      ibps = avctx->bit_rate / (1000 * avctx->channels);
  
      switch ((isampf << 8) +  ibps) {
      case (8 <<8) +  8: tctx->mtab = &mode_08_08; break;
      case (11<<8) +  8: tctx->mtab = &mode_11_08; break;
      case (11<<8) + 10: tctx->mtab = &mode_11_10; break;
      case (16<<8) + 16: tctx->mtab = &mode_16_16; break;
      case (22<<8) + 20: tctx->mtab = &mode_22_20; break;
      case (22<<8) + 24: tctx->mtab = &mode_22_24; break;
      case (22<<8) + 32: tctx->mtab = &mode_22_32; break;
      case (44<<8) + 40: tctx->mtab = &mode_44_40; break;
      case (44<<8) + 48: tctx->mtab = &mode_44_48; break;
      default:
          av_log(avctx, AV_LOG_ERROR, "This version does not support %d kHz - %d kbit/s/ch mode.\n", isampf, isampf);
          return -1;
      }
  
      ff_dsputil_init(&tctx->dsp, avctx);
      if ((ret = init_mdct_win(tctx))) {
          av_log(avctx, AV_LOG_ERROR, "Error initializing MDCT\n");
          twin_decode_close(avctx);
          return ret;
      }
      init_bitstream_params(tctx);
  
      memset_float(tctx->bark_hist[0][0], 0.1, FF_ARRAY_ELEMS(tctx->bark_hist));
  
      avcodec_get_frame_defaults(&tctx->frame);
      avctx->coded_frame = &tctx->frame;
  
      return 0;
  }
  
  AVCodec ff_twinvq_decoder = {
      .name           = "twinvq",
      .type           = AVMEDIA_TYPE_AUDIO,
      .id             = CODEC_ID_TWINVQ,
      .priv_data_size = sizeof(TwinContext),
      .init           = twin_decode_init,
      .close          = twin_decode_close,
      .decode         = twin_decode_frame,
      .capabilities   = CODEC_CAP_DR1,
      .long_name      = NULL_IF_CONFIG_SMALL("VQF TwinVQ"),
  };
  