libfaad2/ic_predict.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: ic_predict.c,v 1.23 2004/09/04 14:56:28 menno Exp $
  26 **/
  27
  28 #include "common.h"
  29 #include "structs.h"
  30
  31 #ifdef MAIN_DEC
  32
  33 #include "syntax.h"
  34 #include "ic_predict.h"
  35 #include "pns.h"
  36
  37
  38 static void flt_round(float32_t *pf)
  39 {
  40     int32_t flg;
  41     uint32_t tmp, tmp1, tmp2;
  42
  43     tmp = *(uint32_t*)pf;
  44     flg = tmp & (uint32_t)0x00008000;
  45     tmp &= (uint32_t)0xffff0000;
  46     tmp1 = tmp;
  47     /* round 1/2 lsb toward infinity */
  48     if (flg)
  49     {
  50         tmp &= (uint32_t)0xff800000;       /* extract exponent and sign */
  51         tmp |= (uint32_t)0x00010000;       /* insert 1 lsb */
  52         tmp2 = tmp;                             /* add 1 lsb and elided one */
  53         tmp &= (uint32_t)0xff800000;       /* extract exponent and sign */
  54
  55         *pf = *(float32_t*)&tmp1 + *(float32_t*)&tmp2 - *(float32_t*)&tmp;
  56     } else {
  57         *pf = *(float32_t*)&tmp;
  58     }
  59 }
  60
  61 static int16_t quant_pred(float32_t x)
  62 {
  63     int16_t q;
  64     uint32_t *tmp = (uint32_t*)&x;
  65
  66     q = (int16_t)(*tmp>>16);
  67
  68     return q;
  69 }
  70
  71 static float32_t inv_quant_pred(int16_t q)
  72 {
  73     float32_t x;
  74     uint32_t *tmp = (uint32_t*)&x;
  75     *tmp = ((uint32_t)q)<<16;
  76
  77     return x;
  78 }
  79
  80 static void ic_predict(pred_state *state, real_t input, real_t *output, uint8_t pred)
  81 {
  82     uint16_t tmp;
  83     int16_t i, j;
  84     real_t dr1, predictedvalue;
  85     real_t e0, e1;
  86     real_t k1, k2;
  87
  88     real_t r[2];
  89     real_t COR[2];
  90     real_t VAR[2];
  91
  92     r[0] = inv_quant_pred(state->r[0]);
  93     r[1] = inv_quant_pred(state->r[1]);
  94     COR[0] = inv_quant_pred(state->COR[0]);
  95     COR[1] = inv_quant_pred(state->COR[1]);
  96     VAR[0] = inv_quant_pred(state->VAR[0]);
  97     VAR[1] = inv_quant_pred(state->VAR[1]);
  98
  99
 100 #if 1
 101     tmp = state->VAR[0];
 102     j = (tmp >> 7);
 103     i = tmp & 0x7f;
 104     if (j >= 128)
 105     {
 106         j -= 128;
 107         k1 = COR[0] * exp_table[j] * mnt_table[i];
 108     } else {
 109         k1 = REAL_CONST(0);
 110     }
 111 #else
 112
 113     {
 114 #define B 0.953125
 115         real_t c = COR[0];
 116         real_t v = VAR[0];
 117         real_t tmp;
 118         if (c == 0 || v <= 1)
 119         {
 120             k1 = 0;
 121         } else {
 122             tmp = B / v;
 123             flt_round(&tmp);
 124             k1 = c * tmp;
 125         }
 126     }
 127 #endif
 128
 129     if (pred)
 130     {
 131 #if 1
 132         tmp = state->VAR[1];
 133         j = (tmp >> 7);
 134         i = tmp & 0x7f;
 135         if (j >= 128)
 136         {
 137             j -= 128;
 138             k2 = COR[1] * exp_table[j] * mnt_table[i];
 139         } else {
 140             k2 = REAL_CONST(0);
 141         }
 142 #else
 143
 144 #define B 0.953125
 145         real_t c = COR[1];
 146         real_t v = VAR[1];
 147         real_t tmp;
 148         if (c == 0 || v <= 1)
 149         {
 150             k2 = 0;
 151         } else {
 152             tmp = B / v;
 153             flt_round(&tmp);
 154             k2 = c * tmp;
 155         }
 156 #endif
 157
 158         predictedvalue = k1*r[0] + k2*r[1];
 159         flt_round(&predictedvalue);
 160         *output = input + predictedvalue;
 161     }
 162
 163     /* calculate new state data */
 164     e0 = *output;
 165     e1 = e0 - k1*r[0];
 166     dr1 = k1*e0;
 167
 168     VAR[0] = ALPHA*VAR[0] + 0.5f * (r[0]*r[0] + e0*e0);
 169     COR[0] = ALPHA*COR[0] + r[0]*e0;
 170     VAR[1] = ALPHA*VAR[1] + 0.5f * (r[1]*r[1] + e1*e1);
 171     COR[1] = ALPHA*COR[1] + r[1]*e1;
 172
 173     r[1] = A * (r[0]-dr1);
 174     r[0] = A * e0;
 175
 176     state->r[0] = quant_pred(r[0]);
 177     state->r[1] = quant_pred(r[1]);
 178     state->COR[0] = quant_pred(COR[0]);
 179     state->COR[1] = quant_pred(COR[1]);
 180     state->VAR[0] = quant_pred(VAR[0]);
 181     state->VAR[1] = quant_pred(VAR[1]);
 182 }
 183
 184 static void reset_pred_state(pred_state *state)
 185 {
 186     state->r[0]   = 0;
 187     state->r[1]   = 0;
 188     state->COR[0] = 0;
 189     state->COR[1] = 0;
 190     state->VAR[0] = 0x3F80;
 191     state->VAR[1] = 0x3F80;
 192 }
 193
 194 void pns_reset_pred_state(ic_stream *ics, pred_state *state)
 195 {
 196     uint8_t sfb, g, b;
 197     uint16_t i, offs, offs2;
 198
 199     /* prediction only for long blocks */
 200     if (ics->window_sequence == EIGHT_SHORT_SEQUENCE)
 201         return;
 202
 203     for (g = 0; g < ics->num_window_groups; g++)
 204     {
 205         for (b = 0; b < ics->window_group_length[g]; b++)
 206         {
 207             for (sfb = 0; sfb < ics->max_sfb; sfb++)
 208             {
 209                 if (is_noise(ics, g, sfb))
 210                 {
 211                     offs = ics->swb_offset[sfb];
 212                     offs2 = ics->swb_offset[sfb+1];
 213
 214                     for (i = offs; i < offs2; i++)
 215                         reset_pred_state(&state[i]);
 216                 }
 217             }
 218         }
 219     }
 220 }
 221
 222 void reset_all_predictors(pred_state *state, uint16_t frame_len)
 223 {
 224     uint16_t i;
 225
 226     for (i = 0; i < frame_len; i++)
 227         reset_pred_state(&state[i]);
 228 }
 229
 230 /* intra channel prediction */
 231 void ic_prediction(ic_stream *ics, real_t *spec, pred_state *state,
 232                    uint16_t frame_len, uint8_t sf_index)
 233 {
 234     uint8_t sfb;
 235     uint16_t bin;
 236
 237     if (ics->window_sequence == EIGHT_SHORT_SEQUENCE)
 238     {
 239         reset_all_predictors(state, frame_len);
 240     } else {
 241         for (sfb = 0; sfb < max_pred_sfb(sf_index); sfb++)
 242         {
 243             uint16_t low  = ics->swb_offset[sfb];
 244             uint16_t high = ics->swb_offset[sfb+1];
 245
 246             for (bin = low; bin < high; bin++)
 247             {
 248                 ic_predict(&state[bin], spec[bin], &spec[bin],
 249                     (ics->predictor_data_present && ics->pred.prediction_used[sfb]));
 250             }
 251         }
 252
 253         if (ics->predictor_data_present)
 254         {
 255             if (ics->pred.predictor_reset)
 256             {
 257                 for (bin = ics->pred.predictor_reset_group_number - 1;
 258                      bin < frame_len; bin += 30)
 259                 {
 260                     reset_pred_state(&state[bin]);
 261                 }
 262             }
 263         }
 264     }
 265 }
 266
 267 #endif