libfaad2/ssr.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: ssr.c,v 1.15 2004/09/04 14:56:29 menno Exp $
  26 **/
  27
  28 #include "common.h"
  29 #include "structs.h"
  30
  31 #ifdef SSR_DEC
  32
  33 #include "syntax.h"
  34 #include "filtbank.h"
  35 #include "ssr.h"
  36 #include "ssr_fb.h"
  37
  38 void ssr_decode(ssr_info *ssr, fb_info *fb, uint8_t window_sequence,
  39                 uint8_t window_shape, uint8_t window_shape_prev,
  40                 real_t *freq_in, real_t *time_out, real_t *overlap,
  41                 real_t ipqf_buffer[SSR_BANDS][96/4],
  42                 real_t *prev_fmd, uint16_t frame_len)
  43 {
  44     uint8_t band;
  45     uint16_t ssr_frame_len = frame_len/SSR_BANDS;
  46     real_t time_tmp[2048] = {0};
  47     real_t output[1024] = {0};
  48
  49     for (band = 0; band < SSR_BANDS; band++)
  50     {
  51         int16_t j;
  52
  53         /* uneven bands have inverted frequency scale */
  54         if (band == 1 || band == 3)
  55         {
  56             for (j = 0; j < ssr_frame_len/2; j++)
  57             {
  58                 real_t tmp;
  59                 tmp = freq_in[j + ssr_frame_len*band];
  60                 freq_in[j + ssr_frame_len*band] =
  61                     freq_in[ssr_frame_len - j - 1 + ssr_frame_len*band];
  62                 freq_in[ssr_frame_len - j - 1 + ssr_frame_len*band] = tmp;
  63             }
  64         }
  65
  66         /* non-overlapping inverse filterbank for SSR */
  67         ssr_ifilter_bank(fb, window_sequence, window_shape, window_shape_prev,
  68             freq_in + band*ssr_frame_len, time_tmp + band*ssr_frame_len,
  69             ssr_frame_len);
  70
  71         /* gain control */
  72         ssr_gain_control(ssr, time_tmp, output, overlap, prev_fmd,
  73             band, window_sequence, ssr_frame_len);
  74     }
  75
  76     /* inverse pqf to bring subbands together again */
  77     ssr_ipqf(ssr, output, time_out, ipqf_buffer, frame_len, SSR_BANDS);
  78 }
  79
  80 static void ssr_gain_control(ssr_info *ssr, real_t *data, real_t *output,
  81                              real_t *overlap, real_t *prev_fmd, uint8_t band,
  82                              uint8_t window_sequence, uint16_t frame_len)
  83 {
  84     uint16_t i;
  85     real_t gc_function[2*1024/SSR_BANDS];
  86
  87     if (window_sequence != EIGHT_SHORT_SEQUENCE)
  88     {
  89         ssr_gc_function(ssr, &prev_fmd[band * frame_len*2],
  90             gc_function, window_sequence, band, frame_len);
  91
  92         for (i = 0; i < frame_len*2; i++)
  93             data[band * frame_len*2 + i] *= gc_function[i];
  94         for (i = 0; i < frame_len; i++)
  95         {
  96             output[band*frame_len + i] = overlap[band*frame_len + i] +
  97                 data[band*frame_len*2 + i];
  98         }
  99         for (i = 0; i < frame_len; i++)
 100         {
 101             overlap[band*frame_len + i] =
 102                 data[band*frame_len*2 + frame_len + i];
 103         }
 104     } else {
 105         uint8_t w;
 106         for (w = 0; w < 8; w++)
 107         {
 108             uint16_t frame_len8 = frame_len/8;
 109             uint16_t frame_len16 = frame_len/16;
 110
 111             ssr_gc_function(ssr, &prev_fmd[band*frame_len*2 + w*frame_len*2/8],
 112                 gc_function, window_sequence, frame_len);
 113
 114             for (i = 0; i < frame_len8*2; i++)
 115                 data[band*frame_len*2 + w*frame_len8*2+i] *= gc_function[i];
 116             for (i = 0; i < frame_len8; i++)
 117             {
 118                 overlap[band*frame_len + i + 7*frame_len16 + w*frame_len8] +=
 119                     data[band*frame_len*2 + 2*w*frame_len8 + i];
 120             }
 121             for (i = 0; i < frame_len8; i++)
 122             {
 123                 overlap[band*frame_len + i + 7*frame_len16 + (w+1)*frame_len8] =
 124                     data[band*frame_len*2 + 2*w*frame_len8 + frame_len8 + i];
 125             }
 126         }
 127         for (i = 0; i < frame_len; i++)
 128             output[band*frame_len + i] = overlap[band*frame_len + i];
 129         for (i = 0; i < frame_len; i++)
 130             overlap[band*frame_len + i] = overlap[band*frame_len + i + frame_len];
 131     }
 132 }
 133
 134 static void ssr_gc_function(ssr_info *ssr, real_t *prev_fmd,
 135                             real_t *gc_function, uint8_t window_sequence,
 136                             uint8_t band, uint16_t frame_len)
 137 {
 138     uint16_t i;
 139     uint16_t len_area1, len_area2;
 140     int32_t aloc[10];
 141     real_t alev[10];
 142
 143     switch (window_sequence)
 144     {
 145     case ONLY_LONG_SEQUENCE:
 146         len_area1 = frame_len/SSR_BANDS;
 147         len_area2 = 0;
 148         break;
 149     case LONG_START_SEQUENCE:
 150         len_area1 = (frame_len/SSR_BANDS)*7/32;
 151         len_area2 = (frame_len/SSR_BANDS)/16;
 152         break;
 153     case EIGHT_SHORT_SEQUENCE:
 154         len_area1 = (frame_len/8)/SSR_BANDS;
 155         len_area2 = 0;
 156         break;
 157     case LONG_STOP_SEQUENCE:
 158         len_area1 = (frame_len/SSR_BANDS);
 159         len_area2 = 0;
 160         break;
 161     }
 162
 163     /* decode bitstream information */
 164
 165     /* build array M */
 166
 167
 168     for (i = 0; i < frame_len*2; i++)
 169         gc_function[i] = 1;
 170 }
 171
 172 #endif