tsiry-sandratraina.com
A modern Music Player Daemon based on Rockbox open source high quality audio player
libadwaita
audio
rust
zig
deno
mpris
rockbox
mpd
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** $Id$
26**/
27
28#include "common.h"
29#include "structs.h"
30
31#include "pns.h"
32
33
34/* static function declarations */
35static void gen_rand_vector(real_t *spec, int16_t scale_factor, uint16_t size,
36 uint8_t sub);
37
38
39#ifdef FIXED_POINT
40
41#define step(shift) \
42 if ((0x40000000l >> shift) + root <= value) \
43 { \
44 value -= (0x40000000l >> shift) + root; \
45 root = (root >> 1) | (0x40000000l >> shift); \
46 } else { \
47 root = root >> 1; \
48 }
49
50/* fixed point square root approximation */
51/* !!!! ONLY WORKS FOR EVEN %REAL_BITS% !!!! */
52static real_t fp_sqrt(real_t value)
53{
54 real_t root = 0;
55
56 step( 0); step( 2); step( 4); step( 6);
57 step( 8); step(10); step(12); step(14);
58 step(16); step(18); step(20); step(22);
59 step(24); step(26); step(28); step(30);
60
61 if (root < value)
62 ++root;
63
64 root <<= (REAL_BITS/2);
65
66 return root;
67}
68
69static real_t pow2_table[] =
70{
71 COEF_CONST(1.0),
72 COEF_CONST(1.18920711500272),
73 COEF_CONST(1.41421356237310),
74 COEF_CONST(1.68179283050743)
75};
76#endif
77
78/* The function gen_rand_vector(addr, size) generates a vector of length
79 <size> with signed random values of average energy MEAN_NRG per random
80 value. A suitable random number generator can be realized using one
81 multiplication/accumulation per random value.
82*/
83static INLINE void gen_rand_vector(real_t *spec, int16_t scale_factor, uint16_t size,
84 uint8_t sub)
85{
86#ifndef FIXED_POINT
87 uint16_t i;
88 real_t energy = 0.0;
89
90 real_t scale = (real_t)1.0/(real_t)size;
91
92 for (i = 0; i < size; i++)
93 {
94 real_t tmp = scale*(real_t)(int32_t)random_int();
95 spec[i] = tmp;
96 energy += tmp*tmp;
97 }
98
99 scale = (real_t)1.0/(real_t)sqrt(energy);
100 scale *= (real_t)pow(2.0, 0.25 * scale_factor);
101 for (i = 0; i < size; i++)
102 {
103 spec[i] *= scale;
104 }
105#else
106 uint16_t i;
107 real_t energy = 0, scale;
108 int32_t exp, frac;
109
110 for (i = 0; i < size; i++)
111 {
112 /* this can be replaced by a 16 bit random generator!!!! */
113 real_t tmp = (int32_t)random_int();
114 if (tmp < 0)
115 tmp = -(tmp & ((1<<(REAL_BITS-1))-1));
116 else
117 tmp = (tmp & ((1<<(REAL_BITS-1))-1));
118
119 energy += MUL_R(tmp,tmp);
120
121 spec[i] = tmp;
122 }
123
124 energy = fp_sqrt(energy);
125 if (energy > 0)
126 {
127 scale = DIV_R(REAL_CONST(1), energy);
128
129 exp = scale_factor >> 2;
130 frac = scale_factor & 3;
131
132 /* IMDCT pre-scaling */
133 exp -= sub;
134
135 if (exp < 0)
136 scale >>= -exp;
137 else
138 scale <<= exp;
139
140 if (frac)
141 scale = MUL_C(scale, pow2_table[frac]);
142
143 for (i = 0; i < size; i++)
144 {
145 spec[i] = MUL_R(spec[i], scale);
146 }
147 }
148#endif
149}
150
151void pns_decode(ic_stream *ics_left, ic_stream *ics_right,
152 real_t *spec_left, real_t *spec_right, uint16_t frame_len,
153 uint8_t channel_pair, uint8_t object_type)
154{
155 uint8_t g, sfb, b;
156 uint16_t size, offs;
157
158 uint8_t group = 0;
159 uint16_t nshort = frame_len >> 3;
160
161 uint8_t sub = 0;
162
163#ifdef FIXED_POINT
164 /* IMDCT scaling */
165 if (object_type == LD)
166 {
167 sub = 9 /*9*/;
168 } else {
169 if (ics_left->window_sequence == EIGHT_SHORT_SEQUENCE)
170 sub = 7 /*7*/;
171 else
172 sub = 10 /*10*/;
173 }
174#endif
175
176 for (g = 0; g < ics_left->num_window_groups; g++)
177 {
178 /* Do perceptual noise substitution decoding */
179 for (b = 0; b < ics_left->window_group_length[g]; b++)
180 {
181 for (sfb = 0; sfb < ics_left->max_sfb; sfb++)
182 {
183 if (is_noise(ics_left, g, sfb))
184 {
185#ifdef LTP_DEC
186 /* Simultaneous use of LTP and PNS is not prevented in the
187 syntax. If both LTP, and PNS are enabled on the same
188 scalefactor band, PNS takes precedence, and no prediction
189 is applied to this band.
190 */
191 ics_left->ltp.long_used[sfb] = 0;
192 ics_left->ltp2.long_used[sfb] = 0;
193#endif
194
195#ifdef MAIN_DEC
196 /* For scalefactor bands coded using PNS the corresponding
197 predictors are switched to "off".
198 */
199 ics_left->pred.prediction_used[sfb] = 0;
200#endif
201
202 offs = ics_left->swb_offset[sfb];
203 size = ics_left->swb_offset[sfb+1] - offs;
204
205 /* Generate random vector */
206 gen_rand_vector(&spec_left[(group*nshort)+offs],
207 ics_left->scale_factors[g][sfb], size, sub);
208 }
209
210/* From the spec:
211 If the same scalefactor band and group is coded by perceptual noise
212 substitution in both channels of a channel pair, the correlation of
213 the noise signal can be controlled by means of the ms_used field: While
214 the default noise generation process works independently for each channel
215 (separate generation of random vectors), the same random vector is used
216 for both channels if ms_used[] is set for a particular scalefactor band
217 and group. In this case, no M/S stereo coding is carried out (because M/S
218 stereo coding and noise substitution coding are mutually exclusive).
219 If the same scalefactor band and group is coded by perceptual noise
220 substitution in only one channel of a channel pair the setting of ms_used[]
221 is not evaluated.
222*/
223 if (channel_pair)
224 {
225 if (is_noise(ics_right, g, sfb))
226 {
227 if (((ics_left->ms_mask_present == 1) &&
228 (ics_left->ms_used[g][sfb])) ||
229 (ics_left->ms_mask_present == 2))
230 {
231 uint16_t c;
232
233 offs = ics_right->swb_offset[sfb];
234 size = ics_right->swb_offset[sfb+1] - offs;
235
236 for (c = 0; c < size; c++)
237 {
238 spec_right[(group*nshort) + offs + c] =
239 spec_left[(group*nshort) + offs + c];
240 }
241 } else /*if (ics_left->ms_mask_present == 0)*/ {
242#ifdef LTP_DEC
243 ics_right->ltp.long_used[sfb] = 0;
244 ics_right->ltp2.long_used[sfb] = 0;
245#endif
246#ifdef MAIN_DEC
247 ics_right->pred.prediction_used[sfb] = 0;
248#endif
249
250 offs = ics_right->swb_offset[sfb];
251 size = ics_right->swb_offset[sfb+1] - offs;
252
253 /* Generate random vector */
254 gen_rand_vector(&spec_right[(group*nshort)+offs],
255 ics_right->scale_factors[g][sfb], size, sub);
256 }
257 }
258 }
259 } /* sfb */
260 group++;
261 } /* b */
262 } /* g */
263}