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 <stddef.h>
30 #include <stdio.h>
31 #include <string.h>
32
33 #include "libavutil/thread.h"
34
35 #include "avcodec.h"
36 #include "atrac.h"
37
38 float ff_atrac_sf_table[64];
39 static float qmf_window[48];
40
41 static const float qmf_48tap_half[24] = {
42 -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,
43 0.0002422519, -0.00085293897,-0.0005205574, 0.0020340169,
44 0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
45 -0.000061169922,-0.01344162, 0.0024626821, 0.021736089,
46 -0.007801671, -0.034090221, 0.01880949, 0.054326009,
47 -0.043596379, -0.099384367, 0.13207909, 0.46424159
48 };
49
atrac_generate_tables(void)50 static av_cold void atrac_generate_tables(void)
51 {
52 /* Generate scale factors */
53 for (int i = 0; i < 64; i++)
54 ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0);
55
56 /* Generate the QMF window. */
57 for (int i = 0; i < 24; i++) {
58 float s = qmf_48tap_half[i] * 2.0;
59 qmf_window[i] = qmf_window[47 - i] = s;
60 }
61 }
62
ff_atrac_generate_tables(void)63 av_cold void ff_atrac_generate_tables(void)
64 {
65 static AVOnce init_static_once = AV_ONCE_INIT;
66 ff_thread_once(&init_static_once, atrac_generate_tables);
67 }
68
ff_atrac_init_gain_compensation(AtracGCContext * gctx,int id2exp_offset,int loc_scale)69 av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,
70 int loc_scale)
71 {
72 int i;
73
74 gctx->loc_scale = loc_scale;
75 gctx->loc_size = 1 << loc_scale;
76 gctx->id2exp_offset = id2exp_offset;
77
78 /* Generate gain level table. */
79 for (i = 0; i < 16; i++)
80 gctx->gain_tab1[i] = powf(2.0, id2exp_offset - i);
81
82 /* Generate gain interpolation table. */
83 for (i = -15; i < 16; i++)
84 gctx->gain_tab2[i + 15] = powf(2.0, -1.0f / gctx->loc_size * i);
85 }
86
ff_atrac_gain_compensation(AtracGCContext * gctx,float * in,float * prev,AtracGainInfo * gc_now,AtracGainInfo * gc_next,int num_samples,float * out)87 void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,
88 AtracGainInfo *gc_now, AtracGainInfo *gc_next,
89 int num_samples, float *out)
90 {
91 float lev, gc_scale, gain_inc;
92 int i, pos, lastpos;
93
94 gc_scale = gc_next->num_points ? gctx->gain_tab1[gc_next->lev_code[0]]
95 : 1.0f;
96
97 if (!gc_now->num_points) {
98 for (pos = 0; pos < num_samples; pos++)
99 out[pos] = in[pos] * gc_scale + prev[pos];
100 } else {
101 pos = 0;
102
103 for (i = 0; i < gc_now->num_points; i++) {
104 lastpos = gc_now->loc_code[i] << gctx->loc_scale;
105
106 lev = gctx->gain_tab1[gc_now->lev_code[i]];
107 gain_inc = gctx->gain_tab2[(i + 1 < gc_now->num_points ? gc_now->lev_code[i + 1]
108 : gctx->id2exp_offset) -
109 gc_now->lev_code[i] + 15];
110
111 /* apply constant gain level and overlap */
112 for (; pos < lastpos; pos++)
113 out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
114
115 /* interpolate between two different gain levels */
116 for (; pos < lastpos + gctx->loc_size; pos++) {
117 out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
118 lev *= gain_inc;
119 }
120 }
121
122 for (; pos < num_samples; pos++)
123 out[pos] = in[pos] * gc_scale + prev[pos];
124 }
125
126 /* copy the overlapping part into the delay buffer */
127 memcpy(prev, &in[num_samples], num_samples * sizeof(float));
128 }
129
ff_atrac_iqmf(float * inlo,float * inhi,unsigned int nIn,float * pOut,float * delayBuf,float * temp)130 void ff_atrac_iqmf(float *inlo, float *inhi, unsigned int nIn, float *pOut,
131 float *delayBuf, float *temp)
132 {
133 int i, j;
134 float *p1, *p3;
135
136 memcpy(temp, delayBuf, 46*sizeof(float));
137
138 p3 = temp + 46;
139
140 /* loop1 */
141 for(i=0; i<nIn; i+=2){
142 p3[2*i+0] = inlo[i ] + inhi[i ];
143 p3[2*i+1] = inlo[i ] - inhi[i ];
144 p3[2*i+2] = inlo[i+1] + inhi[i+1];
145 p3[2*i+3] = inlo[i+1] - inhi[i+1];
146 }
147
148 /* loop2 */
149 p1 = temp;
150 for (j = nIn; j != 0; j--) {
151 float s1 = 0.0;
152 float s2 = 0.0;
153
154 for (i = 0; i < 48; i += 2) {
155 s1 += p1[i] * qmf_window[i];
156 s2 += p1[i+1] * qmf_window[i+1];
157 }
158
159 pOut[0] = s2;
160 pOut[1] = s1;
161
162 p1 += 2;
163 pOut += 2;
164 }
165
166 /* Update the delay buffer. */
167 memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));
168 }
169