1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
/*
* The simplest AC-3 encoder
* Copyright (c) 2000 Fabrice Bellard
* Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* floating-point AC-3 encoder.
*/
#define CONFIG_AC3ENC_FLOAT 1
#include "ac3enc.h"
#include "eac3enc.h"
#include "kbdwin.h"
#if CONFIG_AC3_ENCODER
#define AC3ENC_TYPE AC3ENC_TYPE_AC3
#include "ac3enc_opts_template.c"
static AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name,
ac3_options, LIBAVUTIL_VERSION_INT };
#endif
#include "ac3enc_template.c"
/**
* Finalize MDCT and free allocated memory.
*/
av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)
{
ff_mdct_end(&s->mdct);
av_freep(&s->mdct_window);
}
/**
* Initialize MDCT tables.
* @param nbits log2(MDCT size)
*/
av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
{
float *window;
int i, n, n2;
n = 1 << 9;
n2 = n >> 1;
window = av_malloc(n * sizeof(*window));
if (!window) {
av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
return AVERROR(ENOMEM);
}
ff_kbd_window_init(window, 5.0, n2);
for (i = 0; i < n2; i++)
window[n-1-i] = window[i];
s->mdct_window = window;
return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);
}
/**
* Apply KBD window to input samples prior to MDCT.
*/
static void apply_window(DSPContext *dsp, float *output, const float *input,
const float *window, unsigned int len)
{
dsp->vector_fmul(output, input, window, len);
}
/**
* Normalize the input samples.
* Not needed for the floating-point encoder.
*/
static int normalize_samples(AC3EncodeContext *s)
{
return 0;
}
/**
* Scale MDCT coefficients from float to 24-bit fixed-point.
*/
static void scale_coefficients(AC3EncodeContext *s)
{
int chan_size = AC3_MAX_COEFS * AC3_MAX_BLOCKS;
s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + chan_size,
s->mdct_coef_buffer + chan_size,
chan_size * s->channels);
}
/**
* Clip MDCT coefficients to allowable range.
*/
static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len)
{
dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
}
#if CONFIG_AC3_ENCODER
AVCodec ff_ac3_encoder = {
"ac3",
AVMEDIA_TYPE_AUDIO,
CODEC_ID_AC3,
sizeof(AC3EncodeContext),
ff_ac3_encode_init,
ff_ac3_float_encode_frame,
ff_ac3_encode_close,
NULL,
.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_FLT,AV_SAMPLE_FMT_NONE},
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
.priv_class = &ac3enc_class,
.channel_layouts = ff_ac3_channel_layouts,
};
#endif
|
