blob: dc64ceea52292a08986cc0c914321dad5a3fe4c6
| 1 | /* |
| 2 | ** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding |
| 3 | ** Copyright (C) 2003-2005 M. Bakker, Nero 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 | ** The "appropriate copyright message" mentioned in section 2c of the GPLv2 |
| 23 | ** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com" |
| 24 | ** |
| 25 | ** Commercial non-GPL licensing of this software is possible. |
| 26 | ** For more info contact Nero AG through Mpeg4AAClicense@nero.com. |
| 27 | ** |
| 28 | ** $Id: is.c,v 1.28 2007/11/01 12:33:31 menno Exp $ |
| 29 | **/ |
| 30 | |
| 31 | #include "common.h" |
| 32 | #include "structs.h" |
| 33 | |
| 34 | #include "syntax.h" |
| 35 | #include "is.h" |
| 36 | |
| 37 | #ifdef FIXED_POINT |
| 38 | static real_t pow05_table[] = { |
| 39 | COEF_CONST(1.68179283050743), /* 0.5^(-3/4) */ |
| 40 | COEF_CONST(1.41421356237310), /* 0.5^(-2/4) */ |
| 41 | COEF_CONST(1.18920711500272), /* 0.5^(-1/4) */ |
| 42 | COEF_CONST(1.0), /* 0.5^( 0/4) */ |
| 43 | COEF_CONST(0.84089641525371), /* 0.5^(+1/4) */ |
| 44 | COEF_CONST(0.70710678118655), /* 0.5^(+2/4) */ |
| 45 | COEF_CONST(0.59460355750136) /* 0.5^(+3/4) */ |
| 46 | }; |
| 47 | #endif |
| 48 | |
| 49 | void is_decode(ic_stream *ics, ic_stream *icsr, real_t *l_spec, real_t *r_spec, |
| 50 | uint16_t frame_len) |
| 51 | { |
| 52 | uint8_t g, sfb, b; |
| 53 | uint16_t i; |
| 54 | #ifndef FIXED_POINT |
| 55 | real_t scale; |
| 56 | #else |
| 57 | int32_t exp, frac; |
| 58 | #endif |
| 59 | |
| 60 | uint16_t nshort = frame_len / 8; |
| 61 | uint8_t group = 0; |
| 62 | |
| 63 | for (g = 0; g < icsr->num_window_groups; g++) { |
| 64 | /* Do intensity stereo decoding */ |
| 65 | for (b = 0; b < icsr->window_group_length[g]; b++) { |
| 66 | for (sfb = 0; sfb < icsr->max_sfb; sfb++) { |
| 67 | if (is_intensity(icsr, g, sfb)) { |
| 68 | #ifdef MAIN_DEC |
| 69 | /* For scalefactor bands coded in intensity stereo the |
| 70 | corresponding predictors in the right channel are |
| 71 | switched to "off". |
| 72 | */ |
| 73 | ics->pred.prediction_used[sfb] = 0; |
| 74 | icsr->pred.prediction_used[sfb] = 0; |
| 75 | #endif |
| 76 | |
| 77 | #ifndef FIXED_POINT |
| 78 | scale = (real_t)pow(0.5, (0.25 * icsr->scale_factors[g][sfb])); |
| 79 | #else |
| 80 | exp = icsr->scale_factors[g][sfb] >> 2; |
| 81 | frac = icsr->scale_factors[g][sfb] & 3; |
| 82 | #endif |
| 83 | |
| 84 | /* Scale from left to right channel, |
| 85 | do not touch left channel */ |
| 86 | for (i = icsr->swb_offset[sfb]; i < min(icsr->swb_offset[sfb + 1], ics->swb_offset_max); i++) { |
| 87 | #ifndef FIXED_POINT |
| 88 | r_spec[(group * nshort) + i] = MUL_R(l_spec[(group * nshort) + i], scale); |
| 89 | #else |
| 90 | if (exp < 0) { |
| 91 | r_spec[(group * nshort) + i] = l_spec[(group * nshort) + i] << -exp; |
| 92 | } else { |
| 93 | r_spec[(group * nshort) + i] = l_spec[(group * nshort) + i] >> exp; |
| 94 | } |
| 95 | r_spec[(group * nshort) + i] = MUL_C(r_spec[(group * nshort) + i], pow05_table[frac + 3]); |
| 96 | #endif |
| 97 | if (is_intensity(icsr, g, sfb) != invert_intensity(ics, g, sfb)) { |
| 98 | r_spec[(group * nshort) + i] = -r_spec[(group * nshort) + i]; |
| 99 | } |
| 100 | } |
| 101 | } |
| 102 | } |
| 103 | group++; |
| 104 | } |
| 105 | } |
| 106 | } |
| 107 |