libfaad2/sbr_hfgen.c

   1 /*
   2 ** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
   3 ** Copyright (C) 2003-2004 M. Bakker, Ahead Software AG, http://www.nero.com
   4 **
   5 ** This program is free software; you can redistribute it and/or modify
   6 ** it under the terms of the GNU General Public License as published by
   7 ** the Free Software Foundation; either version 2 of the License, or
   8 ** (at your option) any later version.
   9 **
  10 ** This program is distributed in the hope that it will be useful,
  11 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 ** GNU General Public License for more details.
  14 **
  15 ** You should have received a copy of the GNU General Public License
  16 ** along with this program; if not, write to the Free Software
  17 ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18 **
  19 ** Any non-GPL usage of this software or parts of this software is strictly
  20 ** forbidden.
  21 **
  22 ** Commercial non-GPL licensing of this software is possible.
  23 ** For more info contact Ahead Software through Mpeg4AAClicense@nero.com.
  24 **
  25 ** $Id: sbr_hfgen.c,v 1.22 2004/09/08 09:43:11 gcp Exp $
  26 **/
  27
  28 /* High Frequency generation */
  29
  30 #include "common.h"
  31 #include "structs.h"
  32
  33 #ifdef SBR_DEC
  34
  35 #include "sbr_syntax.h"
  36 #include "sbr_hfgen.h"
  37 #include "sbr_fbt.h"
  38
  39
  40 /* static function declarations */
  41 #ifdef SBR_LOW_POWER
  42 static void calc_prediction_coef_lp(sbr_info *sbr, qmf_t Xlow[MAX_NTSRHFG][64],
  43                                     complex_t *alpha_0, complex_t *alpha_1, real_t *rxx);
  44 static void calc_aliasing_degree(sbr_info *sbr, real_t *rxx, real_t *deg);
  45 #else
  46 static void calc_prediction_coef(sbr_info *sbr, qmf_t Xlow[MAX_NTSRHFG][64],
  47                                  complex_t *alpha_0, complex_t *alpha_1, uint8_t k);
  48 #endif
  49 static void calc_chirp_factors(sbr_info *sbr, uint8_t ch);
  50 static void patch_construction(sbr_info *sbr);
  51
  52
  53 void hf_generation(sbr_info *sbr, qmf_t Xlow[MAX_NTSRHFG][64],
  54                    qmf_t Xhigh[MAX_NTSRHFG][64]
  55 #ifdef SBR_LOW_POWER
  56                    ,real_t *deg
  57 #endif
  58                    ,uint8_t ch)
  59 {
  60     uint8_t l, i, x;
  61     ALIGN complex_t alpha_0[64], alpha_1[64];
  62 #ifdef SBR_LOW_POWER
  63     ALIGN real_t rxx[64];
  64 #endif
  65
  66     uint8_t offset = sbr->tHFAdj;
  67     uint8_t first = sbr->t_E[ch][0];
  68     uint8_t last = sbr->t_E[ch][sbr->L_E[ch]];
  69
  70     calc_chirp_factors(sbr, ch);
  71
  72 #ifdef SBR_LOW_POWER
  73     memset(deg, 0, 64*sizeof(real_t));
  74 #endif
  75
  76     if ((ch == 0) && (sbr->Reset))
  77         patch_construction(sbr);
  78
  79     /* calculate the prediction coefficients */
  80 #ifdef SBR_LOW_POWER
  81     calc_prediction_coef_lp(sbr, Xlow, alpha_0, alpha_1, rxx);
  82     calc_aliasing_degree(sbr, rxx, deg);
  83 #endif
  84
  85     /* actual HF generation */
  86     for (i = 0; i < sbr->noPatches; i++)
  87     {
  88         for (x = 0; x < sbr->patchNoSubbands[i]; x++)
  89         {
  90             real_t a0_r, a0_i, a1_r, a1_i;
  91             real_t bw, bw2;
  92             uint8_t q, p, k, g;
  93
  94             /* find the low and high band for patching */
  95             k = sbr->kx + x;
  96             for (q = 0; q < i; q++)
  97             {
  98                 k += sbr->patchNoSubbands[q];
  99             }
 100             p = sbr->patchStartSubband[i] + x;
 101
 102 #ifdef SBR_LOW_POWER
 103             if (x != 0 /*x < sbr->patchNoSubbands[i]-1*/)
 104                 deg[k] = deg[p];
 105             else
 106                 deg[k] = 0;
 107 #endif
 108
 109             g = sbr->table_map_k_to_g[k];
 110
 111             bw = sbr->bwArray[ch][g];
 112             bw2 = MUL_C(bw, bw);
 113
 114             /* do the patching */
 115             /* with or without filtering */
 116             if (bw2 > 0)
 117             {
 118                 real_t temp1_r, temp2_r, temp3_r;
 119 #ifndef SBR_LOW_POWER
 120                 real_t temp1_i, temp2_i, temp3_i;
 121                 calc_prediction_coef(sbr, Xlow, alpha_0, alpha_1, p);
 122 #endif
 123
 124                 a0_r = MUL_C(RE(alpha_0[p]), bw);
 125                 a1_r = MUL_C(RE(alpha_1[p]), bw2);
 126 #ifndef SBR_LOW_POWER
 127                 a0_i = MUL_C(IM(alpha_0[p]), bw);
 128                 a1_i = MUL_C(IM(alpha_1[p]), bw2);
 129 #endif
 130
 131                 temp2_r = QMF_RE(Xlow[first - 2 + offset][p]);
 132                 temp3_r = QMF_RE(Xlow[first - 1 + offset][p]);
 133 #ifndef SBR_LOW_POWER
 134                 temp2_i = QMF_IM(Xlow[first - 2 + offset][p]);
 135                 temp3_i = QMF_IM(Xlow[first - 1 + offset][p]);
 136 #endif
 137                                 for (l = first; l < last; l++)
 138                 {
 139                         temp1_r = temp2_r;
 140                         temp2_r = temp3_r;
 141                         temp3_r = QMF_RE(Xlow[l + offset][p]);
 142 #ifndef SBR_LOW_POWER
 143                         temp1_i = temp2_i;
 144                         temp2_i = temp3_i;
 145                     temp3_i = QMF_IM(Xlow[l + offset][p]);
 146 #endif
 147
 148 #ifdef SBR_LOW_POWER
 149                     QMF_RE(Xhigh[l + offset][k]) =
 150                         temp3_r
 151                       +(MUL_R(a0_r, temp2_r) +
 152                         MUL_R(a1_r, temp1_r));
 153 #else
 154                     QMF_RE(Xhigh[l + offset][k]) =
 155                         temp3_r
 156                       +(MUL_R(a0_r, temp2_r) -
 157                         MUL_R(a0_i, temp2_i) +
 158                         MUL_R(a1_r, temp1_r) -
 159                         MUL_R(a1_i, temp1_i));
 160                     QMF_IM(Xhigh[l + offset][k]) =
 161                         temp3_i
 162                       +(MUL_R(a0_i, temp2_r) +
 163                         MUL_R(a0_r, temp2_i) +
 164                         MUL_R(a1_i, temp1_r) +
 165                         MUL_R(a1_r, temp1_i));
 166 #endif
 167                 }
 168             } else {
 169                 for (l = first; l < last; l++)
 170                 {
 171                     QMF_RE(Xhigh[l + offset][k]) = QMF_RE(Xlow[l + offset][p]);
 172 #ifndef SBR_LOW_POWER
 173                     QMF_IM(Xhigh[l + offset][k]) = QMF_IM(Xlow[l + offset][p]);
 174 #endif
 175                 }
 176             }
 177         }
 178     }
 179
 180     if (sbr->Reset)
 181     {
 182         limiter_frequency_table(sbr);
 183     }
 184 }
 185
 186 typedef struct
 187 {
 188     complex_t r01;
 189     complex_t r02;
 190     complex_t r11;
 191     complex_t r12;
 192     complex_t r22;
 193     real_t det;
 194 } acorr_coef;
 195
 196 #ifdef SBR_LOW_POWER
 197 static void auto_correlation(sbr_info *sbr, acorr_coef *ac,
 198                              qmf_t buffer[MAX_NTSRHFG][64],
 199                              uint8_t bd, uint8_t len)
 200 {
 201     real_t r01 = 0, r02 = 0, r11 = 0;
 202     int8_t j;
 203     uint8_t offset = sbr->tHFAdj;
 204 #ifdef FIXED_POINT
 205     const real_t rel = FRAC_CONST(0.999999); // 1 / (1 + 1e-6f);
 206     uint32_t maxi = 0;
 207     uint32_t pow2, exp;
 208 #else
 209     const real_t rel = 1 / (1 + 1e-6f);
 210 #endif
 211
 212
 213 #ifdef FIXED_POINT
 214     mask = 0;
 215
 216     for (j = (offset-2); j < (len + offset); j++)
 217     {
 218         real_t x;
 219         x = QMF_RE(buffer[j][bd])>>REAL_BITS;
 220         mask |= x ^ (x >> 31);
 221     }
 222
 223     exp = wl_min_lzc(mask);
 224
 225     /* improves accuracy */
 226     if (exp > 0)
 227         exp -= 1;
 228
 229     for (j = offset; j < len + offset; j++)
 230     {
 231         real_t buf_j = ((QMF_RE(buffer[j][bd])+(1<<(exp-1)))>>exp);
 232         real_t buf_j_1 = ((QMF_RE(buffer[j-1][bd])+(1<<(exp-1)))>>exp);
 233         real_t buf_j_2 = ((QMF_RE(buffer[j-2][bd])+(1<<(exp-1)))>>exp);
 234
 235         /* normalisation with rounding */
 236         r01 += MUL_R(buf_j, buf_j_1);
 237         r02 += MUL_R(buf_j, buf_j_2);
 238         r11 += MUL_R(buf_j_1, buf_j_1);
 239     }
 240     RE(ac->r12) = r01 -
 241         MUL_R(((QMF_RE(buffer[len+offset-1][bd])+(1<<(exp-1)))>>exp), ((QMF_RE(buffer[len+offset-2][bd])+(1<<(exp-1)))>>exp)) +
 242         MUL_R(((QMF_RE(buffer[offset-1][bd])+(1<<(exp-1)))>>exp), ((QMF_RE(buffer[offset-2][bd])+(1<<(exp-1)))>>exp));
 243     RE(ac->r22) = r11 -
 244         MUL_R(((QMF_RE(buffer[len+offset-2][bd])+(1<<(exp-1)))>>exp), ((QMF_RE(buffer[len+offset-2][bd])+(1<<(exp-1)))>>exp)) +
 245         MUL_R(((QMF_RE(buffer[offset-2][bd])+(1<<(exp-1)))>>exp), ((QMF_RE(buffer[offset-2][bd])+(1<<(exp-1)))>>exp));
 246 #else
 247     for (j = offset; j < len + offset; j++)
 248     {
 249         r01 += QMF_RE(buffer[j][bd]) * QMF_RE(buffer[j-1][bd]);
 250         r02 += QMF_RE(buffer[j][bd]) * QMF_RE(buffer[j-2][bd]);
 251         r11 += QMF_RE(buffer[j-1][bd]) * QMF_RE(buffer[j-1][bd]);
 252     }
 253     RE(ac->r12) = r01 -
 254         QMF_RE(buffer[len+offset-1][bd]) * QMF_RE(buffer[len+offset-2][bd]) +
 255         QMF_RE(buffer[offset-1][bd]) * QMF_RE(buffer[offset-2][bd]);
 256     RE(ac->r22) = r11 -
 257         QMF_RE(buffer[len+offset-2][bd]) * QMF_RE(buffer[len+offset-2][bd]) +
 258         QMF_RE(buffer[offset-2][bd]) * QMF_RE(buffer[offset-2][bd]);
 259 #endif
 260     RE(ac->r01) = r01;
 261     RE(ac->r02) = r02;
 262     RE(ac->r11) = r11;
 263
 264     ac->det = MUL_R(RE(ac->r11), RE(ac->r22)) - MUL_F(MUL_R(RE(ac->r12), RE(ac->r12)), rel);
 265 }
 266 #else
 267 static void auto_correlation(sbr_info *sbr, acorr_coef *ac, qmf_t buffer[MAX_NTSRHFG][64],
 268                              uint8_t bd, uint8_t len)
 269 {
 270     real_t r01r = 0, r01i = 0, r02r = 0, r02i = 0, r11r = 0;
 271     real_t temp1_r, temp1_i, temp2_r, temp2_i, temp3_r, temp3_i, temp4_r, temp4_i, temp5_r, temp5_i;
 272 #ifdef FIXED_POINT
 273     const real_t rel = FRAC_CONST(0.999999); // 1 / (1 + 1e-6f);
 274     uint32_t mask, exp;
 275     real_t pow2_to_exp;
 276 #else
 277     const real_t rel = 1 / (1 + 1e-6f);
 278 #endif
 279     int8_t j;
 280     uint8_t offset = sbr->tHFAdj;
 281
 282 #ifdef FIXED_POINT
 283     mask = 0;
 284
 285     for (j = (offset-2); j < (len + offset); j++)
 286     {
 287         real_t x;
 288         x = QMF_RE(buffer[j][bd])>>REAL_BITS;
 289         mask |= x ^ (x >> 31);
 290         x = QMF_IM(buffer[j][bd])>>REAL_BITS;
 291         mask |= x ^ (x >> 31);
 292     }
 293
 294     exp = wl_min_lzc(mask);
 295
 296     /* improves accuracy */
 297     if (exp > 0)
 298         exp -= 1;
 299
 300     pow2_to_exp = 1<<(exp-1);
 301
 302     temp2_r = (QMF_RE(buffer[offset-2][bd]) + pow2_to_exp) >> exp;
 303     temp2_i = (QMF_IM(buffer[offset-2][bd]) + pow2_to_exp) >> exp;
 304     temp3_r = (QMF_RE(buffer[offset-1][bd]) + pow2_to_exp) >> exp;
 305     temp3_i = (QMF_IM(buffer[offset-1][bd]) + pow2_to_exp) >> exp;
 306     // Save these because they are needed after loop
 307     temp4_r = temp2_r;
 308     temp4_i = temp2_i;
 309     temp5_r = temp3_r;
 310     temp5_i = temp3_i;
 311
 312     for (j = offset; j < len + offset; j++)
 313     {
 314         temp1_r = temp2_r; // temp1_r = (QMF_RE(buffer[offset-2][bd] + (1<<(exp-1))) >> exp;
 315         temp1_i = temp2_i; // temp1_i = (QMF_IM(buffer[offset-2][bd] + (1<<(exp-1))) >> exp;
 316         temp2_r = temp3_r; // temp2_r = (QMF_RE(buffer[offset-1][bd] + (1<<(exp-1))) >> exp;
 317         temp2_i = temp3_i; // temp2_i = (QMF_IM(buffer[offset-1][bd] + (1<<(exp-1))) >> exp;
 318         temp3_r = (QMF_RE(buffer[j][bd]) + pow2_to_exp) >> exp;
 319         temp3_i = (QMF_IM(buffer[j][bd]) + pow2_to_exp) >> exp;
 320         r01r += MUL_R(temp3_r, temp2_r) + MUL_R(temp3_i, temp2_i);
 321         r01i += MUL_R(temp3_i, temp2_r) - MUL_R(temp3_r, temp2_i);
 322         r02r += MUL_R(temp3_r, temp1_r) + MUL_R(temp3_i, temp1_i);
 323         r02i += MUL_R(temp3_i, temp1_r) - MUL_R(temp3_r, temp1_i);
 324         r11r += MUL_R(temp2_r, temp2_r) + MUL_R(temp2_i, temp2_i);
 325     }
 326
 327     // These are actual values in temporary variable at this point
 328     // temp1_r = (QMF_RE(buffer[len+offset-1-2][bd] + (1<<(exp-1))) >> exp;
 329     // temp1_i = (QMF_IM(buffer[len+offset-1-2][bd] + (1<<(exp-1))) >> exp;
 330     // temp2_r = (QMF_RE(buffer[len+offset-1-1][bd] + (1<<(exp-1))) >> exp;
 331     // temp2_i = (QMF_IM(buffer[len+offset-1-1][bd] + (1<<(exp-1))) >> exp;
 332     // temp3_r = (QMF_RE(buffer[len+offset-1][bd]) + (1<<(exp-1))) >> exp;
 333     // temp3_i = (QMF_IM(buffer[len+offset-1][bd]) + (1<<(exp-1))) >> exp;
 334     // temp4_r = (QMF_RE(buffer[offset-2][bd]) + (1<<(exp-1))) >> exp;
 335     // temp4_i = (QMF_IM(buffer[offset-2][bd]) + (1<<(exp-1))) >> exp;
 336     // temp5_r = (QMF_RE(buffer[offset-1][bd]) + (1<<(exp-1))) >> exp;
 337     // temp5_i = (QMF_IM(buffer[offset-1][bd]) + (1<<(exp-1))) >> exp;
 338
 339     RE(ac->r12) = r01r -
 340         (MUL_R(temp3_r, temp2_r) + MUL_R(temp3_i, temp2_i)) +
 341         (MUL_R(temp5_r, temp4_r) + MUL_R(temp5_i, temp4_i));
 342     IM(ac->r12) = r01i -
 343         (MUL_R(temp3_i, temp2_r) - MUL_R(temp3_r, temp2_i)) +
 344         (MUL_R(temp5_i, temp4_r) - MUL_R(temp5_r, temp4_i));
 345     RE(ac->r22) = r11r -
 346         (MUL_R(temp2_r, temp2_r) + MUL_R(temp2_i, temp2_i)) +
 347         (MUL_R(temp4_r, temp4_r) + MUL_R(temp4_i, temp4_i));
 348
 349 #else
 350
 351     temp2_r = QMF_RE(buffer[offset-2][bd]);
 352     temp2_i = QMF_IM(buffer[offset-2][bd]);
 353     temp3_r = QMF_RE(buffer[offset-1][bd]);
 354     temp3_i = QMF_IM(buffer[offset-1][bd]);
 355     // Save these because they are needed after loop
 356     temp4_r = temp2_r;
 357     temp4_i = temp2_i;
 358     temp5_r = temp3_r;
 359     temp5_i = temp3_i;
 360
 361     for (j = offset; j < len + offset; j++)
 362     {
 363         temp1_r = temp2_r; // temp1_r = QMF_RE(buffer[j-2][bd];
 364         temp1_i = temp2_i; // temp1_i = QMF_IM(buffer[j-2][bd];
 365         temp2_r = temp3_r; // temp2_r = QMF_RE(buffer[j-1][bd];
 366         temp2_i = temp3_i; // temp2_i = QMF_IM(buffer[j-1][bd];
 367         temp3_r = QMF_RE(buffer[j][bd]);
 368         temp3_i = QMF_IM(buffer[j][bd]);
 369         r01r += temp3_r * temp2_r + temp3_i * temp2_i;
 370         r01i += temp3_i * temp2_r - temp3_r * temp2_i;
 371         r02r += temp3_r * temp1_r + temp3_i * temp1_i;
 372         r02i += temp3_i * temp1_r - temp3_r * temp1_i;
 373         r11r += temp2_r * temp2_r + temp2_i * temp2_i;
 374     }
 375
 376     // These are actual values in temporary variable at this point
 377     // temp1_r = QMF_RE(buffer[len+offset-1-2][bd];
 378     // temp1_i = QMF_IM(buffer[len+offset-1-2][bd];
 379     // temp2_r = QMF_RE(buffer[len+offset-1-1][bd];
 380     // temp2_i = QMF_IM(buffer[len+offset-1-1][bd];
 381     // temp3_r = QMF_RE(buffer[len+offset-1][bd]);
 382     // temp3_i = QMF_IM(buffer[len+offset-1][bd]);
 383     // temp4_r = QMF_RE(buffer[offset-2][bd]);
 384     // temp4_i = QMF_IM(buffer[offset-2][bd]);
 385     // temp5_r = QMF_RE(buffer[offset-1][bd]);
 386     // temp5_i = QMF_IM(buffer[offset-1][bd]);
 387
 388     RE(ac->r12) = r01r -
 389         (temp3_r * temp2_r + temp3_i * temp2_i) +
 390         (temp5_r * temp4_r + temp5_i * temp4_i);
 391     IM(ac->r12) = r01i -
 392         (temp3_i * temp2_r - temp3_r * temp2_i) +
 393         (temp5_i * temp4_r - temp5_r * temp4_i);
 394     RE(ac->r22) = r11r -
 395         (temp2_r * temp2_r + temp2_i * temp2_i) +
 396         (temp4_r * temp4_r + temp4_i * temp4_i);
 397
 398 #endif
 399
 400     RE(ac->r01) = r01r;
 401     IM(ac->r01) = r01i;
 402     RE(ac->r02) = r02r;
 403     IM(ac->r02) = r02i;
 404     RE(ac->r11) = r11r;
 405
 406     ac->det = MUL_R(RE(ac->r11), RE(ac->r22)) - MUL_F(rel, (MUL_R(RE(ac->r12), RE(ac->r12)) + MUL_R(IM(ac->r12), IM(ac->r12))));
 407 }
 408 #endif
 409
 410 /* calculate linear prediction coefficients using the covariance method */
 411 #ifndef SBR_LOW_POWER
 412 static void calc_prediction_coef(sbr_info *sbr, qmf_t Xlow[MAX_NTSRHFG][64],
 413                                  complex_t *alpha_0, complex_t *alpha_1, uint8_t k)
 414 {
 415     real_t tmp;
 416     acorr_coef ac;
 417
 418     auto_correlation(sbr, &ac, Xlow, k, sbr->numTimeSlotsRate + 6);
 419
 420     if (ac.det == 0)
 421     {
 422         RE(alpha_1[k]) = 0;
 423         IM(alpha_1[k]) = 0;
 424     } else {
 425 #ifdef FIXED_POINT
 426         tmp = (MUL_R(RE(ac.r01), RE(ac.r12)) - MUL_R(IM(ac.r01), IM(ac.r12)) - MUL_R(RE(ac.r02), RE(ac.r11)));
 427         RE(alpha_1[k]) = DIV_R(tmp, ac.det);
 428         tmp = (MUL_R(IM(ac.r01), RE(ac.r12)) + MUL_R(RE(ac.r01), IM(ac.r12)) - MUL_R(IM(ac.r02), RE(ac.r11)));
 429         IM(alpha_1[k]) = DIV_R(tmp, ac.det);
 430 #else
 431         tmp = REAL_CONST(1.0) / ac.det;
 432         RE(alpha_1[k]) = (MUL_R(RE(ac.r01), RE(ac.r12)) - MUL_R(IM(ac.r01), IM(ac.r12)) - MUL_R(RE(ac.r02), RE(ac.r11))) * tmp;
 433         IM(alpha_1[k]) = (MUL_R(IM(ac.r01), RE(ac.r12)) + MUL_R(RE(ac.r01), IM(ac.r12)) - MUL_R(IM(ac.r02), RE(ac.r11))) * tmp;
 434 #endif
 435     }
 436
 437     if (RE(ac.r11) == 0)
 438     {
 439         RE(alpha_0[k]) = 0;
 440         IM(alpha_0[k]) = 0;
 441     } else {
 442 #ifdef FIXED_POINT
 443         tmp = -(RE(ac.r01) + MUL_R(RE(alpha_1[k]), RE(ac.r12)) + MUL_R(IM(alpha_1[k]), IM(ac.r12)));
 444         RE(alpha_0[k]) = DIV_R(tmp, RE(ac.r11));
 445         tmp = -(IM(ac.r01) + MUL_R(IM(alpha_1[k]), RE(ac.r12)) - MUL_R(RE(alpha_1[k]), IM(ac.r12)));
 446         IM(alpha_0[k]) = DIV_R(tmp, RE(ac.r11));
 447 #else
 448         tmp = 1.0f / RE(ac.r11);
 449         RE(alpha_0[k]) = -(RE(ac.r01) + MUL_R(RE(alpha_1[k]), RE(ac.r12)) + MUL_R(IM(alpha_1[k]), IM(ac.r12))) * tmp;
 450         IM(alpha_0[k]) = -(IM(ac.r01) + MUL_R(IM(alpha_1[k]), RE(ac.r12)) - MUL_R(RE(alpha_1[k]), IM(ac.r12))) * tmp;
 451 #endif
 452     }
 453
 454     if ((MUL_R(RE(alpha_0[k]),RE(alpha_0[k])) + MUL_R(IM(alpha_0[k]),IM(alpha_0[k])) >= REAL_CONST(16)) ||
 455         (MUL_R(RE(alpha_1[k]),RE(alpha_1[k])) + MUL_R(IM(alpha_1[k]),IM(alpha_1[k])) >= REAL_CONST(16)))
 456     {
 457         RE(alpha_0[k]) = 0;
 458         IM(alpha_0[k]) = 0;
 459         RE(alpha_1[k]) = 0;
 460         IM(alpha_1[k]) = 0;
 461     }
 462 }
 463 #else
 464 static void calc_prediction_coef_lp(sbr_info *sbr, qmf_t Xlow[MAX_NTSRHFG][64],
 465                                     complex_t *alpha_0, complex_t *alpha_1, real_t *rxx)
 466 {
 467     uint8_t k;
 468     real_t tmp;
 469     acorr_coef ac;
 470
 471     for (k = 1; k < sbr->f_master[0]; k++)
 472     {
 473         auto_correlation(sbr, &ac, Xlow, k, sbr->numTimeSlotsRate + 6);
 474
 475         if (ac.det == 0)
 476         {
 477             RE(alpha_0[k]) = 0;
 478             RE(alpha_1[k]) = 0;
 479         } else {
 480             tmp = MUL_R(RE(ac.r01), RE(ac.r22)) - MUL_R(RE(ac.r12), RE(ac.r02));
 481             RE(alpha_0[k]) = DIV_R(tmp, (-ac.det));
 482
 483             tmp = MUL_R(RE(ac.r01), RE(ac.r12)) - MUL_R(RE(ac.r02), RE(ac.r11));
 484             RE(alpha_1[k]) = DIV_R(tmp, ac.det);
 485         }
 486
 487         if ((RE(alpha_0[k]) >= REAL_CONST(4)) || (RE(alpha_1[k]) >= REAL_CONST(4)))
 488         {
 489             RE(alpha_0[k]) = REAL_CONST(0);
 490             RE(alpha_1[k]) = REAL_CONST(0);
 491         }
 492
 493         /* reflection coefficient */
 494         if (RE(ac.r11) == 0)
 495         {
 496             rxx[k] = COEF_CONST(0.0);
 497         } else {
 498             rxx[k] = DIV_C(RE(ac.r01), RE(ac.r11));
 499             rxx[k] = -rxx[k];
 500             if (rxx[k] > COEF_CONST(1.0)) rxx[k] = COEF_CONST(1.0);
 501             if (rxx[k] < COEF_CONST(-1.0)) rxx[k] = COEF_CONST(-1.0);
 502         }
 503     }
 504 }
 505
 506 static void calc_aliasing_degree(sbr_info *sbr, real_t *rxx, real_t *deg)
 507 {
 508     uint8_t k;
 509
 510     rxx[0] = COEF_CONST(0.0);
 511     deg[1] = COEF_CONST(0.0);
 512
 513     for (k = 2; k < sbr->k0; k++)
 514     {
 515         deg[k] = 0.0;
 516
 517         if ((k % 2 == 0) && (rxx[k] < COEF_CONST(0.0)))
 518         {
 519             if (rxx[k-1] < 0.0)
 520             {
 521                 deg[k] = COEF_CONST(1.0);
 522
 523                 if (rxx[k-2] > COEF_CONST(0.0))
 524                 {
 525                     deg[k-1] = COEF_CONST(1.0) - MUL_C(rxx[k-1], rxx[k-1]);
 526                 }
 527             } else if (rxx[k-2] > COEF_CONST(0.0)) {
 528                 deg[k] = COEF_CONST(1.0) - MUL_C(rxx[k-1], rxx[k-1]);
 529             }
 530         }
 531
 532         if ((k % 2 == 1) && (rxx[k] > COEF_CONST(0.0)))
 533         {
 534             if (rxx[k-1] > COEF_CONST(0.0))
 535             {
 536                 deg[k] = COEF_CONST(1.0);
 537
 538                 if (rxx[k-2] < COEF_CONST(0.0))
 539                 {
 540                     deg[k-1] = COEF_CONST(1.0) - MUL_C(rxx[k-1], rxx[k-1]);
 541                 }
 542             } else if (rxx[k-2] < COEF_CONST(0.0)) {
 543                 deg[k] = COEF_CONST(1.0) - MUL_C(rxx[k-1], rxx[k-1]);
 544             }
 545         }
 546     }
 547 }
 548 #endif
 549
 550 /* FIXED POINT: bwArray = COEF */
 551 static real_t mapNewBw(uint8_t invf_mode, uint8_t invf_mode_prev)
 552 {
 553     switch (invf_mode)
 554     {
 555     case 1: /* LOW */
 556         if (invf_mode_prev == 0) /* NONE */
 557             return COEF_CONST(0.6);
 558         else
 559             return COEF_CONST(0.75);
 560
 561     case 2: /* MID */
 562         return COEF_CONST(0.9);
 563
 564     case 3: /* HIGH */
 565         return COEF_CONST(0.98);
 566
 567     default: /* NONE */
 568         if (invf_mode_prev == 1) /* LOW */
 569             return COEF_CONST(0.6);
 570         else
 571             return COEF_CONST(0.0);
 572     }
 573 }
 574
 575 /* FIXED POINT: bwArray = COEF */
 576 static void calc_chirp_factors(sbr_info *sbr, uint8_t ch)
 577 {
 578     uint8_t i;
 579
 580     for (i = 0; i < sbr->N_Q; i++)
 581     {
 582         sbr->bwArray[ch][i] = mapNewBw(sbr->bs_invf_mode[ch][i], sbr->bs_invf_mode_prev[ch][i]);
 583
 584         if (sbr->bwArray[ch][i] < sbr->bwArray_prev[ch][i])
 585             sbr->bwArray[ch][i] = MUL_F(sbr->bwArray[ch][i], FRAC_CONST(0.75)) + MUL_F(sbr->bwArray_prev[ch][i], FRAC_CONST(0.25));
 586         else
 587             sbr->bwArray[ch][i] = MUL_F(sbr->bwArray[ch][i], FRAC_CONST(0.90625)) + MUL_F(sbr->bwArray_prev[ch][i], FRAC_CONST(0.09375));
 588
 589         if (sbr->bwArray[ch][i] < COEF_CONST(0.015625))
 590             sbr->bwArray[ch][i] = COEF_CONST(0.0);
 591
 592         if (sbr->bwArray[ch][i] >= COEF_CONST(0.99609375))
 593             sbr->bwArray[ch][i] = COEF_CONST(0.99609375);
 594
 595         sbr->bwArray_prev[ch][i] = sbr->bwArray[ch][i];
 596         sbr->bs_invf_mode_prev[ch][i] = sbr->bs_invf_mode[ch][i];
 597     }
 598 }
 599
 600 static void patch_construction(sbr_info *sbr)
 601 {
 602     uint8_t i, k;
 603     uint8_t odd, sb;
 604     uint8_t msb = sbr->k0;
 605     uint8_t usb = sbr->kx;
 606     uint8_t goalSbTab[] = { 21, 23, 32, 43, 46, 64, 85, 93, 128, 0, 0, 0 };
 607     /* (uint8_t)(2.048e6/sbr->sample_rate + 0.5); */
 608     uint8_t goalSb = goalSbTab[get_sr_index(sbr->sample_rate)];
 609
 610     sbr->noPatches = 0;
 611
 612     if (goalSb < (sbr->kx + sbr->M))
 613     {
 614         for (i = 0, k = 0; sbr->f_master[i] < goalSb; i++)
 615             k = i+1;
 616     } else {
 617         k = sbr->N_master;
 618     }
 619
 620     if (sbr->N_master == 0)
 621     {
 622         sbr->noPatches = 0;
 623         sbr->patchNoSubbands[0] = 0;
 624         sbr->patchStartSubband[0] = 0;
 625
 626         return;
 627     }
 628
 629     do
 630     {
 631         uint8_t j = k + 1;
 632
 633         do
 634         {
 635             j--;
 636
 637             sb = sbr->f_master[j];
 638             odd = (sb - 2 + sbr->k0) % 2;
 639         } while (sb > (sbr->k0 - 1 + msb - odd));
 640
 641         sbr->patchNoSubbands[sbr->noPatches] = max(sb - usb, 0);
 642         sbr->patchStartSubband[sbr->noPatches] = sbr->k0 - odd -
 643             sbr->patchNoSubbands[sbr->noPatches];
 644
 645         if (sbr->patchNoSubbands[sbr->noPatches] > 0)
 646         {
 647             usb = sb;
 648             msb = sb;
 649             sbr->noPatches++;
 650         } else {
 651             msb = sbr->kx;
 652         }
 653
 654         if (sbr->f_master[k] - sb < 3)
 655             k = sbr->N_master;
 656     } while (sb != (sbr->kx + sbr->M));
 657
 658     if ((sbr->patchNoSubbands[sbr->noPatches-1] < 3) && (sbr->noPatches > 1))
 659     {
 660         sbr->noPatches--;
 661     }
 662
 663     sbr->noPatches = min(sbr->noPatches, 5);
 664 }
 665
 666 #endif