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 * floating-point AC-3 encoder.
27 */
28
29 #define AC3ENC_FLOAT 1
35
36
37 /*
38 * Scale MDCT coefficients from float to 24-bit fixed-point.
39 */
41 {
44 s->ac3dsp.float_to_fixed24(
s->fixed_coef_buffer + (chan_size * !cpl),
45 s->mdct_coef_buffer + (chan_size * !cpl),
46 chan_size * (
s->channels + cpl));
47 }
48
49
50 /*
51 * Clip MDCT coefficients to allowable range.
52 */
55 {
57 }
58
59
60 /*
61 * Calculate a single coupling coordinate.
62 */
64 {
65 float coord = 0.125;
66 if (energy_cpl > 0)
67 coord *=
sqrtf(energy_ch / energy_cpl);
69 }
70
72 const float *coef0, const float *coef1,
74 {
75 s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1,
len);
76 }
77
79
80 /**
81 * Initialize MDCT tables.
82 *
83 * @param s AC-3 encoder private context
84 * @return 0 on success, negative error code on failure
85 */
87 {
89
91
94 }
95
96
98 {
101
106
110
112 }
113
130 };