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