libfaad2/lt_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: lt_predict.c,v 1.21 2004/02/26 09:29:27 menno Exp $
  26 **/
  27
  28
  29 #include "common.h"
  30 #include "structs.h"
  31
  32 #ifdef LTP_DEC
  33
  34 #include <stdlib.h>
  35 #include "syntax.h"
  36 #include "lt_predict.h"
  37 #include "filtbank.h"
  38 #include "tns.h"
  39
  40
  41 /* static function declarations */
  42 static int16_t real_to_int16(real_t sig_in);
  43
  44
  45 /* check if the object type is an object type that can have LTP */
  46 uint8_t is_ltp_ot(uint8_t object_type)
  47 {
  48 #ifdef LTP_DEC
  49     if ((object_type == LTP)
  50 #ifdef ERROR_RESILIENCE
  51         || (object_type == ER_LTP)
  52 #endif
  53 #ifdef LD_DEC
  54         || (object_type == LD)
  55 #endif
  56 #ifdef SCALABLE_DEC
  57         || (object_type == 6) /* TODO */
  58 #endif
  59         )
  60     {
  61         return 1;
  62     }
  63 #endif
  64
  65     return 0;
  66 }
  67
  68 ALIGN static const real_t codebook[8] =
  69 {
  70     REAL_CONST(0.570829),
  71     REAL_CONST(0.696616),
  72     REAL_CONST(0.813004),
  73     REAL_CONST(0.911304),
  74     REAL_CONST(0.984900),
  75     REAL_CONST(1.067894),
  76     REAL_CONST(1.194601),
  77     REAL_CONST(1.369533)
  78 };
  79
  80 void lt_prediction(ic_stream *ics, ltp_info *ltp, real_t *spec,
  81                    int16_t *lt_pred_stat, fb_info *fb, uint8_t win_shape,
  82                    uint8_t win_shape_prev, uint8_t sr_index,
  83                    uint8_t object_type, uint16_t frame_len)
  84 {
  85     uint8_t sfb;
  86     uint16_t bin, i, num_samples;
  87     ALIGN real_t x_est[2048];
  88     ALIGN real_t X_est[2048];
  89
  90     if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)
  91     {
  92         if (ltp->data_present)
  93         {
  94             num_samples = frame_len << 1;
  95
  96             for(i = 0; i < num_samples; i++)
  97             {
  98                 /* The extra lookback M (N/2 for LD, 0 for LTP) is handled
  99                    in the buffer updating */
 100
 101 #if 0
 102                 x_est[i] = MUL_R_C(lt_pred_stat[num_samples + i - ltp->lag],
 103                     codebook[ltp->coef]);
 104 #else
 105                 /* lt_pred_stat is a 16 bit int, multiplied with the fixed point real
 106                    this gives a real for x_est
 107                 */
 108                 x_est[i] = (real_t)lt_pred_stat[num_samples + i - ltp->lag] * codebook[ltp->coef];
 109 #endif
 110             }
 111
 112             filter_bank_ltp(fb, ics->window_sequence, win_shape, win_shape_prev,
 113                 x_est, X_est, object_type, frame_len);
 114
 115             tns_encode_frame(ics, &(ics->tns), sr_index, object_type, X_est,
 116                 frame_len);
 117
 118             for (sfb = 0; sfb < ltp->last_band; sfb++)
 119             {
 120                 if (ltp->long_used[sfb])
 121                 {
 122                     uint16_t low  = ics->swb_offset[sfb];
 123                     uint16_t high = ics->swb_offset[sfb+1];
 124
 125                     for (bin = low; bin < high; bin++)
 126                     {
 127                         spec[bin] += X_est[bin];
 128                     }
 129                 }
 130             }
 131         }
 132     }
 133 }
 134
 135 #ifdef FIXED_POINT
 136 static INLINE int16_t real_to_int16(real_t sig_in)
 137 {
 138     if (sig_in >= 0)
 139     {
 140         sig_in += (1 << (REAL_BITS-1));
 141         if (sig_in >= REAL_CONST(32768))
 142             return 32767;
 143     } else {
 144         sig_in += -(1 << (REAL_BITS-1));
 145         if (sig_in <= REAL_CONST(-32768))
 146             return -32768;
 147     }
 148
 149     return (sig_in >> REAL_BITS);
 150 }
 151 #else
 152 static INLINE int16_t real_to_int16(real_t sig_in)
 153 {
 154     if (sig_in >= 0)
 155     {
 156 #ifndef HAS_LRINTF
 157         sig_in += 0.5f;
 158 #endif
 159         if (sig_in >= 32768.0f)
 160             return 32767;
 161     } else {
 162 #ifndef HAS_LRINTF
 163         sig_in += -0.5f;
 164 #endif
 165         if (sig_in <= -32768.0f)
 166             return -32768;
 167     }
 168
 169     return lrintf(sig_in);
 170 }
 171 #endif
 172
 173 void lt_update_state(int16_t *lt_pred_stat, real_t *time, real_t *overlap,
 174                      uint16_t frame_len, uint8_t object_type)
 175 {
 176     uint16_t i;
 177
 178     /*
 179      * The reference point for index i and the content of the buffer
 180      * lt_pred_stat are arranged so that lt_pred_stat(0 ... N/2 - 1) contains the
 181      * last aliased half window from the IMDCT, and lt_pred_stat(N/2 ... N-1)
 182      * is always all zeros. The rest of lt_pred_stat (i<0) contains the previous
 183      * fully reconstructed time domain samples, i.e., output of the decoder.
 184      *
 185      * These values are shifted up by N*2 to avoid (i<0)
 186      *
 187      * For the LD object type an extra 512 samples lookback is accomodated here.
 188      */
 189 #ifdef LD_DEC
 190     if (object_type == LD)
 191     {
 192         for (i = 0; i < frame_len; i++)
 193         {
 194             lt_pred_stat[i]  /* extra 512 */  = lt_pred_stat[i + frame_len];
 195             lt_pred_stat[frame_len + i]       = lt_pred_stat[i + (frame_len * 2)];
 196             lt_pred_stat[(frame_len * 2) + i] = real_to_int16(time[i]);
 197             lt_pred_stat[(frame_len * 3) + i] = real_to_int16(overlap[i]);
 198         }
 199     } else {
 200 #endif
 201         for (i = 0; i < frame_len; i++)
 202         {
 203             lt_pred_stat[i]                   = lt_pred_stat[i + frame_len];
 204             lt_pred_stat[frame_len + i]       = real_to_int16(time[i]);
 205             lt_pred_stat[(frame_len * 2) + i] = real_to_int16(overlap[i]);
 206 #if 0 /* set to zero once upon initialisation */
 207             lt_pred_stat[(frame_len * 3) + i] = 0;
 208 #endif
 209         }
 210 #ifdef LD_DEC
 211     }
 212 #endif
 213 }
 214
 215 #endif