1 /*
2 * The simplest AC-3 encoder
3 * Copyright (c) 2000 Fabrice Bellard
4 * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
5 * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
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 * fixed-point AC-3 encoder.
27 */
28
29 #define CONFIG_FFT_FLOAT 0
30 #undef CONFIG_AC3ENC_FLOAT
34
35 #define AC3ENC_TYPE AC3ENC_TYPE_AC3_FIXED
37
43 };
44
46
47
48 /**
49 * Finalize MDCT and free allocated memory.
50 *
51 * @param s AC-3 encoder private context
52 */
54 {
56 }
57
58
59 /**
60 * Initialize MDCT tables.
61 *
62 * @param s AC-3 encoder private context
63 * @return 0 on success, negative error code on failure
64 */
66 {
70 }
71
72
73 /*
74 * Apply KBD window to input samples prior to MDCT.
75 */
77 const int16_t *window,
unsigned int len)
78 {
81 }
82
83
84 /*
85 * Normalize the input samples to use the maximum available precision.
86 * This assumes signed 16-bit input samples.
87 */
89 {
92 if (v > 0)
94 /* +6 to right-shift from 31-bit to 25-bit */
95 return v + 6;
96 }
97
98
99 /*
100 * Scale MDCT coefficients to 25-bit signed fixed-point.
101 */
103 {
105
108 for (ch = 1; ch <= s->
channels; ch++) {
111 }
112 }
113 }
114
118 {
120 }
121
122 /*
123 * Clip MDCT coefficients to allowable range.
124 */
126 {
128 }
129
130
131 /*
132 * Calculate a single coupling coordinate.
133 */
135 {
137 return 1048576;
138 } else {
139 uint64_t coord = energy_ch / (energy_cpl >> 24);
140 uint32_t coord32 =
FFMIN(coord, 1073741824);
141 coord32 =
ff_sqrt(coord32) << 9;
143 }
144 }
145
146
148 {
152 }
153
154
169 };