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
30 #include "audiodsp.h"
31 #include "ac3enc.h"
32 #include "codec_internal.h"
33 #include "eac3enc.h"
34 #include "kbdwin.h"
35
36
37 /*
38 * Scale MDCT coefficients from float to 24-bit fixed-point.
39 */
scale_coefficients(AC3EncodeContext *s)40 static void scale_coefficients(AC3EncodeContext *s)
41 {
42 int chan_size = AC3_MAX_COEFS * s->num_blocks;
43 int cpl = s->cpl_on;
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 */
clip_coefficients(AudioDSPContext *adsp, float *coef, unsigned int len)53 static void clip_coefficients(AudioDSPContext *adsp, float *coef,
54 unsigned int len)
55 {
56 adsp->vector_clipf(coef, coef, len, COEF_MIN, COEF_MAX);
57 }
58
59
60 /*
61 * Calculate a single coupling coordinate.
62 */
calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)63 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
64 {
65 float coord = 0.125;
66 if (energy_cpl > 0)
67 coord *= sqrtf(energy_ch / energy_cpl);
68 return FFMIN(coord, COEF_MAX);
69 }
70
sum_square_butterfly(AC3EncodeContext *s, float sum[4], const float *coef0, const float *coef1, int len)71 static void sum_square_butterfly(AC3EncodeContext *s, float sum[4],
72 const float *coef0, const float *coef1,
73 int len)
74 {
75 s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len);
76 }
77
78
79 #include "ac3enc_template.c"
80
81
82 /**
83 * Finalize MDCT and free allocated memory.
84 *
85 * @param s AC-3 encoder private context
86 */
ac3_float_mdct_end(AC3EncodeContext *s)87 static av_cold void ac3_float_mdct_end(AC3EncodeContext *s)
88 {
89 ff_mdct_end(&s->mdct);
90 }
91
92
93 /**
94 * Initialize MDCT tables.
95 *
96 * @param s AC-3 encoder private context
97 * @return 0 on success, negative error code on failure
98 */
ac3_float_mdct_init(AC3EncodeContext *s)99 static av_cold int ac3_float_mdct_init(AC3EncodeContext *s)
100 {
101 float *window = av_malloc_array(AC3_BLOCK_SIZE, sizeof(*window));
102 if (!window) {
103 av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");
104 return AVERROR(ENOMEM);
105 }
106
107 ff_kbd_window_init(window, 5.0, AC3_BLOCK_SIZE);
108 s->mdct_window = window;
109
110 return ff_mdct_init(&s->mdct, 9, 0, -2.0 / AC3_WINDOW_SIZE);
111 }
112
113
ff_ac3_float_encode_init(AVCodecContext *avctx)114 av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx)
115 {
116 AC3EncodeContext *s = avctx->priv_data;
117 s->mdct_end = ac3_float_mdct_end;
118 s->mdct_init = ac3_float_mdct_init;
119 s->allocate_sample_buffers = allocate_sample_buffers;
120 s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
121 if (!s->fdsp)
122 return AVERROR(ENOMEM);
123 return ff_ac3_encode_init(avctx);
124 }
125
126 FF_DISABLE_DEPRECATION_WARNINGS
127 const FFCodec ff_ac3_encoder = {
128 .p.name = "ac3",
129 .p.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
130 .p.type = AVMEDIA_TYPE_AUDIO,
131 .p.id = AV_CODEC_ID_AC3,
132 .p.capabilities = AV_CODEC_CAP_DR1,
133 .priv_data_size = sizeof(AC3EncodeContext),
134 .init = ff_ac3_float_encode_init,
135 FF_CODEC_ENCODE_CB(ff_ac3_float_encode_frame),
136 .close = ff_ac3_encode_close,
137 .p.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
138 AV_SAMPLE_FMT_NONE },
139 .p.priv_class = &ff_ac3enc_class,
140 .p.supported_samplerates = ff_ac3_sample_rate_tab,
141 #if FF_API_OLD_CHANNEL_LAYOUT
142 .p.channel_layouts = ff_ac3_channel_layouts,
143 #endif
144 .p.ch_layouts = ff_ac3_ch_layouts,
145 .defaults = ff_ac3_enc_defaults,
146 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
147 };
148 FF_ENABLE_DEPRECATION_WARNINGS
149