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path: root/audio_codec/libfaad/ssr.c (plain)
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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: ssr.c,v 1.19 2007/11/01 12:33:36 menno Exp $
29**/
30
31#include "common.h"
32#include "structs.h"
33
34#ifdef SSR_DEC
35
36#include "syntax.h"
37#include "filtbank.h"
38#include "ssr.h"
39#include "ssr_fb.h"
40
41void ssr_decode(ssr_info *ssr, fb_info *fb, uint8_t window_sequence,
42 uint8_t window_shape, uint8_t window_shape_prev,
43 real_t *freq_in, real_t *time_out, real_t *overlap,
44 real_t ipqf_buffer[SSR_BANDS][96 / 4],
45 real_t *prev_fmd, uint16_t frame_len)
46{
47 uint8_t band;
48 uint16_t ssr_frame_len = frame_len / SSR_BANDS;
49 real_t time_tmp[2048] = {0};
50 real_t output[1024] = {0};
51
52 for (band = 0; band < SSR_BANDS; band++) {
53 int16_t j;
54
55 /* uneven bands have inverted frequency scale */
56 if (band == 1 || band == 3) {
57 for (j = 0; j < ssr_frame_len / 2; j++) {
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
80static 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 ssr_gc_function(ssr, &prev_fmd[band * frame_len * 2],
89 gc_function, window_sequence, band, frame_len);
90
91 for (i = 0; i < frame_len * 2; i++) {
92 data[band * frame_len * 2 + i] *= gc_function[i];
93 }
94 for (i = 0; i < frame_len; i++) {
95 output[band * frame_len + i] = overlap[band * frame_len + i] +
96 data[band * frame_len * 2 + i];
97 }
98 for (i = 0; i < frame_len; i++) {
99 overlap[band * frame_len + i] =
100 data[band * frame_len * 2 + frame_len + i];
101 }
102 } else {
103 uint8_t w;
104 for (w = 0; w < 8; w++) {
105 uint16_t frame_len8 = frame_len / 8;
106 uint16_t frame_len16 = frame_len / 16;
107
108 ssr_gc_function(ssr, &prev_fmd[band * frame_len * 2 + w * frame_len * 2 / 8],
109 gc_function, window_sequence, frame_len);
110
111 for (i = 0; i < frame_len8 * 2; i++) {
112 data[band * frame_len * 2 + w * frame_len8 * 2 + i] *= gc_function[i];
113 }
114 for (i = 0; i < frame_len8; i++) {
115 overlap[band * frame_len + i + 7 * frame_len16 + w * frame_len8] +=
116 data[band * frame_len * 2 + 2 * w * frame_len8 + i];
117 }
118 for (i = 0; i < frame_len8; i++) {
119 overlap[band * frame_len + i + 7 * frame_len16 + (w + 1)*frame_len8] =
120 data[band * frame_len * 2 + 2 * w * frame_len8 + frame_len8 + i];
121 }
122 }
123 for (i = 0; i < frame_len; i++) {
124 output[band * frame_len + i] = overlap[band * frame_len + i];
125 }
126 for (i = 0; i < frame_len; i++) {
127 overlap[band * frame_len + i] = overlap[band * frame_len + i + frame_len];
128 }
129 }
130}
131
132static void ssr_gc_function(ssr_info *ssr, real_t *prev_fmd,
133 real_t *gc_function, uint8_t window_sequence,
134 uint8_t band, uint16_t frame_len)
135{
136 uint16_t i;
137 uint16_t len_area1, len_area2;
138 int32_t aloc[10];
139 real_t alev[10];
140
141 switch (window_sequence) {
142 case ONLY_LONG_SEQUENCE:
143 len_area1 = frame_len / SSR_BANDS;
144 len_area2 = 0;
145 break;
146 case LONG_START_SEQUENCE:
147 len_area1 = (frame_len / SSR_BANDS) * 7 / 32;
148 len_area2 = (frame_len / SSR_BANDS) / 16;
149 break;
150 case EIGHT_SHORT_SEQUENCE:
151 len_area1 = (frame_len / 8) / SSR_BANDS;
152 len_area2 = 0;
153 break;
154 case LONG_STOP_SEQUENCE:
155 len_area1 = (frame_len / SSR_BANDS);
156 len_area2 = 0;
157 break;
158 }
159
160 /* decode bitstream information */
161
162 /* build array M */
163
164
165 for (i = 0; i < frame_len * 2; i++) {
166 gc_function[i] = 1;
167 }
168}
169
170#endif
171
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