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 Libav.
8 *
9 * Libav 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 * Libav 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 Libav; 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 CONFIG_AC3ENC_FLOAT 1
30#include "ac3enc.h"
31#include "eac3enc.h"
32#include "kbdwin.h"
33
34
35#if CONFIG_AC3_ENCODER
36#define AC3ENC_TYPE AC3ENC_TYPE_AC3
37#include "ac3enc_opts_template.c"
38static const AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name,
39                                      ac3_options, LIBAVUTIL_VERSION_INT };
40#endif
41
42#include "ac3enc_template.c"
43
44
45/**
46 * Finalize MDCT and free allocated memory.
47 *
48 * @param s  AC-3 encoder private context
49 */
50av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)
51{
52    ff_mdct_end(&s->mdct);
53    av_freep(&s->mdct_window);
54}
55
56
57/**
58 * Initialize MDCT tables.
59 *
60 * @param s  AC-3 encoder private context
61 * @return   0 on success, negative error code on failure
62 */
63av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)
64{
65    float *window;
66    int i, n, n2;
67
68    n  = 1 << 9;
69    n2 = n >> 1;
70
71    window = av_malloc(n * sizeof(*window));
72    if (!window) {
73        av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
74        return AVERROR(ENOMEM);
75    }
76    ff_kbd_window_init(window, 5.0, n2);
77    for (i = 0; i < n2; i++)
78        window[n-1-i] = window[i];
79    s->mdct_window = window;
80
81    return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);
82}
83
84
85/*
86 * Apply KBD window to input samples prior to MDCT.
87 */
88static void apply_window(DSPContext *dsp, float *output, const float *input,
89                         const float *window, unsigned int len)
90{
91    dsp->vector_fmul(output, input, window, len);
92}
93
94
95/*
96 * Normalize the input samples.
97 * Not needed for the floating-point encoder.
98 */
99static int normalize_samples(AC3EncodeContext *s)
100{
101    return 0;
102}
103
104
105/*
106 * Scale MDCT coefficients from float to 24-bit fixed-point.
107 */
108static void scale_coefficients(AC3EncodeContext *s)
109{
110    int chan_size = AC3_MAX_COEFS * s->num_blocks;
111    int cpl       = s->cpl_on;
112    s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),
113                               s->mdct_coef_buffer  + (chan_size * !cpl),
114                               chan_size * (s->channels + cpl));
115}
116
117
118/*
119 * Clip MDCT coefficients to allowable range.
120 */
121static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len)
122{
123    dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
124}
125
126
127/*
128 * Calculate a single coupling coordinate.
129 */
130static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
131{
132    float coord = 0.125;
133    if (energy_cpl > 0)
134        coord *= sqrtf(energy_ch / energy_cpl);
135    return FFMIN(coord, COEF_MAX);
136}
137
138
139#if CONFIG_AC3_ENCODER
140AVCodec ff_ac3_encoder = {
141    .name           = "ac3",
142    .type           = AVMEDIA_TYPE_AUDIO,
143    .id             = CODEC_ID_AC3,
144    .priv_data_size = sizeof(AC3EncodeContext),
145    .init           = ff_ac3_encode_init,
146    .encode         = ff_ac3_float_encode_frame,
147    .close          = ff_ac3_encode_close,
148    .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_FLT,AV_SAMPLE_FMT_NONE},
149    .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
150    .priv_class = &ac3enc_class,
151    .channel_layouts = ff_ac3_channel_layouts,
152};
153#endif
154