1 /*
2 * common functions for the ATRAC family of decoders
3 *
4 * Copyright (c) 2006-2013 Maxim Poliakovski
5 * Copyright (c) 2006-2008 Benjamin Larsson
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 /**
25 * @file
26 */
27
28 #include <math.h>
29 #include <string.h>
30
31 #include "libavutil/attributes.h"
32 #include "libavutil/thread.h"
33
34 #include "atrac.h"
35
36 float ff_atrac_sf_table[64];
37 static float qmf_window[48];
38
39 static const float qmf_48tap_half[24] = {
40 -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,
41 0.0002422519, -0.00085293897,-0.0005205574, 0.0020340169,
42 0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
43 -0.000061169922,-0.01344162, 0.0024626821, 0.021736089,
44 -0.007801671, -0.034090221, 0.01880949, 0.054326009,
45 -0.043596379, -0.099384367, 0.13207909, 0.46424159
46 };
47
atrac_generate_tables(void)48 static av_cold void atrac_generate_tables(void)
49 {
50 /* Generate scale factors */
51 for (int i = 0; i < 64; i++)
52 ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0);
53
54 /* Generate the QMF window. */
55 for (int i = 0; i < 24; i++) {
56 float s = qmf_48tap_half[i] * 2.0;
57 qmf_window[i] = qmf_window[47 - i] = s;
58 }
59 }
60
ff_atrac_generate_tables(void)61 av_cold void ff_atrac_generate_tables(void)
62 {
63 static AVOnce init_static_once = AV_ONCE_INIT;
64 ff_thread_once(&init_static_once, atrac_generate_tables);
65 }
66
ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset, int loc_scale)67 av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,
68 int loc_scale)
69 {
70 int i;
71
72 gctx->loc_scale = loc_scale;
73 gctx->loc_size = 1 << loc_scale;
74 gctx->id2exp_offset = id2exp_offset;
75
76 /* Generate gain level table. */
77 for (i = 0; i < 16; i++)
78 gctx->gain_tab1[i] = powf(2.0, id2exp_offset - i);
79
80 /* Generate gain interpolation table. */
81 for (i = -15; i < 16; i++)
82 gctx->gain_tab2[i + 15] = powf(2.0, -1.0f / gctx->loc_size * i);
83 }
84
ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev, AtracGainInfo *gc_now, AtracGainInfo *gc_next, int num_samples, float *out)85 void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,
86 AtracGainInfo *gc_now, AtracGainInfo *gc_next,
87 int num_samples, float *out)
88 {
89 float lev, gc_scale, gain_inc;
90 int i, pos, lastpos;
91
92 gc_scale = gc_next->num_points ? gctx->gain_tab1[gc_next->lev_code[0]]
93 : 1.0f;
94
95 if (!gc_now->num_points) {
96 for (pos = 0; pos < num_samples; pos++)
97 out[pos] = in[pos] * gc_scale + prev[pos];
98 } else {
99 pos = 0;
100
101 for (i = 0; i < gc_now->num_points; i++) {
102 lastpos = gc_now->loc_code[i] << gctx->loc_scale;
103
104 lev = gctx->gain_tab1[gc_now->lev_code[i]];
105 gain_inc = gctx->gain_tab2[(i + 1 < gc_now->num_points ? gc_now->lev_code[i + 1]
106 : gctx->id2exp_offset) -
107 gc_now->lev_code[i] + 15];
108
109 /* apply constant gain level and overlap */
110 for (; pos < lastpos; pos++)
111 out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
112
113 /* interpolate between two different gain levels */
114 for (; pos < lastpos + gctx->loc_size; pos++) {
115 out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
116 lev *= gain_inc;
117 }
118 }
119
120 for (; pos < num_samples; pos++)
121 out[pos] = in[pos] * gc_scale + prev[pos];
122 }
123
124 /* copy the overlapping part into the delay buffer */
125 memcpy(prev, &in[num_samples], num_samples * sizeof(float));
126 }
127
ff_atrac_iqmf(float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)128 void ff_atrac_iqmf(float *inlo, float *inhi, unsigned int nIn, float *pOut,
129 float *delayBuf, float *temp)
130 {
131 int i, j;
132 float *p1, *p3;
133
134 memcpy(temp, delayBuf, 46*sizeof(float));
135
136 p3 = temp + 46;
137
138 /* loop1 */
139 for(i=0; i<nIn; i+=2){
140 p3[2*i+0] = inlo[i ] + inhi[i ];
141 p3[2*i+1] = inlo[i ] - inhi[i ];
142 p3[2*i+2] = inlo[i+1] + inhi[i+1];
143 p3[2*i+3] = inlo[i+1] - inhi[i+1];
144 }
145
146 /* loop2 */
147 p1 = temp;
148 for (j = nIn; j != 0; j--) {
149 float s1 = 0.0;
150 float s2 = 0.0;
151
152 for (i = 0; i < 48; i += 2) {
153 s1 += p1[i] * qmf_window[i];
154 s2 += p1[i+1] * qmf_window[i+1];
155 }
156
157 pOut[0] = s2;
158 pOut[1] = s1;
159
160 p1 += 2;
161 pOut += 2;
162 }
163
164 /* Update the delay buffer. */
165 memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));
166 }
167