FFmpeg
atrac.c
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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 
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 
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 
62 {
63  static AVOnce init_static_once = AV_ONCE_INIT;
64  ff_thread_once(&init_static_once, atrac_generate_tables);
65 }
66 
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 
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 
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 }
out
FILE * out
Definition: movenc.c:54
AtracGCContext::gain_tab2
float gain_tab2[31]
gain compensation interpolation table
Definition: atrac.h:46
thread.h
qmf_window
static float qmf_window[48]
Definition: atrac.c:37
ff_atrac_init_gain_compensation
av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset, int loc_scale)
Initialize gain compensation context.
Definition: atrac.c:67
ff_thread_once
static int ff_thread_once(char *control, void(*routine)(void))
Definition: thread.h:175
av_cold
#define av_cold
Definition: attributes.h:90
s
#define s(width, name)
Definition: cbs_vp9.c:257
atrac.h
s1
#define s1
Definition: regdef.h:38
AtracGainInfo::num_points
int num_points
number of gain control points
Definition: atrac.h:36
AtracGCContext
Gain compensation context structure.
Definition: atrac.h:44
f
#define f(width, name)
Definition: cbs_vp9.c:255
AV_ONCE_INIT
#define AV_ONCE_INIT
Definition: thread.h:173
ff_atrac_sf_table
float ff_atrac_sf_table[64]
Definition: atrac.c:36
AtracGainInfo
Gain control parameters for one subband.
Definition: atrac.h:35
AtracGCContext::loc_scale
int loc_scale
scale of location code = 2^loc_scale samples
Definition: atrac.h:48
AVOnce
#define AVOnce
Definition: thread.h:172
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
s2
#define s2
Definition: regdef.h:39
powf
#define powf(x, y)
Definition: libm.h:50
AtracGainInfo::loc_code
int loc_code[7]
location of gain control points
Definition: atrac.h:38
ff_atrac_generate_tables
av_cold void ff_atrac_generate_tables(void)
Generate common tables.
Definition: atrac.c:61
attributes.h
AtracGCContext::loc_size
int loc_size
size of location code in samples
Definition: atrac.h:49
i
int i
Definition: input.c:406
AtracGCContext::gain_tab1
float gain_tab1[16]
gain compensation level table
Definition: atrac.h:45
lev
static LevelCodes lev[4+3+3]
Definition: clearvideo.c:85
atrac_generate_tables
static av_cold void atrac_generate_tables(void)
Definition: atrac.c:48
pos
unsigned int pos
Definition: spdifenc.c:412
AtracGCContext::id2exp_offset
int id2exp_offset
offset for converting level index into level exponent
Definition: atrac.h:47
AtracGainInfo::lev_code
int lev_code[7]
level at corresponding control point
Definition: atrac.h:37
ff_atrac_gain_compensation
void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev, AtracGainInfo *gc_now, AtracGainInfo *gc_next, int num_samples, float *out)
Apply gain compensation and perform the MDCT overlapping part.
Definition: atrac.c:85
temp
else temp
Definition: vf_mcdeint.c:256
qmf_48tap_half
static const float qmf_48tap_half[24]
Definition: atrac.c:39
ff_atrac_iqmf
void ff_atrac_iqmf(float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)
Quadrature mirror synthesis filter.
Definition: atrac.c:128