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 FFT_FLOAT 0
30 #undef CONFIG_AC3ENC_FLOAT
31 #include "internal.h"
32 #include "audiodsp.h"
33 #include "ac3enc.h"
34 #include "eac3enc.h"
35
36 #define AC3ENC_TYPE AC3ENC_TYPE_AC3_FIXED
37 #include "ac3enc_opts_template.c"
38
39 static const AVClass ac3enc_class = {
40 .class_name = "Fixed-Point AC-3 Encoder",
41 .item_name = av_default_item_name,
42 .option = ac3_options,
43 .version = LIBAVUTIL_VERSION_INT,
44 };
45
46 /*
47 * Normalize the input samples to use the maximum available precision.
48 * This assumes signed 16-bit input samples.
49 */
normalize_samples(AC3EncodeContext * s)50 static int normalize_samples(AC3EncodeContext *s)
51 {
52 int v = s->ac3dsp.ac3_max_msb_abs_int16(s->windowed_samples, AC3_WINDOW_SIZE);
53 v = 14 - av_log2(v);
54 if (v > 0)
55 s->ac3dsp.ac3_lshift_int16(s->windowed_samples, AC3_WINDOW_SIZE, v);
56 /* +6 to right-shift from 31-bit to 25-bit */
57 return v + 6;
58 }
59
60
61 /*
62 * Scale MDCT coefficients to 25-bit signed fixed-point.
63 */
scale_coefficients(AC3EncodeContext * s)64 static void scale_coefficients(AC3EncodeContext *s)
65 {
66 int blk, ch;
67
68 for (blk = 0; blk < s->num_blocks; blk++) {
69 AC3Block *block = &s->blocks[blk];
70 for (ch = 1; ch <= s->channels; ch++) {
71 s->ac3dsp.ac3_rshift_int32(block->mdct_coef[ch], AC3_MAX_COEFS,
72 block->coeff_shift[ch]);
73 }
74 }
75 }
76
sum_square_butterfly(AC3EncodeContext * s,int64_t sum[4],const int32_t * coef0,const int32_t * coef1,int len)77 static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4],
78 const int32_t *coef0, const int32_t *coef1,
79 int len)
80 {
81 s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len);
82 }
83
84 /*
85 * Clip MDCT coefficients to allowable range.
86 */
clip_coefficients(AudioDSPContext * adsp,int32_t * coef,unsigned int len)87 static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef,
88 unsigned int len)
89 {
90 adsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
91 }
92
93
94 /*
95 * Calculate a single coupling coordinate.
96 */
calc_cpl_coord(CoefSumType energy_ch,CoefSumType energy_cpl)97 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
98 {
99 if (energy_cpl <= COEF_MAX) {
100 return 1048576;
101 } else {
102 uint64_t coord = energy_ch / (energy_cpl >> 24);
103 uint32_t coord32 = FFMIN(coord, 1073741824);
104 coord32 = ff_sqrt(coord32) << 9;
105 return FFMIN(coord32, COEF_MAX);
106 }
107 }
108
109
110 #include "ac3enc_template.c"
111
112
113 /**
114 * Finalize MDCT and free allocated memory.
115 *
116 * @param s AC-3 encoder private context
117 */
ff_ac3_fixed_mdct_end(AC3EncodeContext * s)118 av_cold void ff_ac3_fixed_mdct_end(AC3EncodeContext *s)
119 {
120 ff_mdct_end(&s->mdct);
121 }
122
123
124 /**
125 * Initialize MDCT tables.
126 *
127 * @param s AC-3 encoder private context
128 * @return 0 on success, negative error code on failure
129 */
ff_ac3_fixed_mdct_init(AC3EncodeContext * s)130 av_cold int ff_ac3_fixed_mdct_init(AC3EncodeContext *s)
131 {
132 int ret = ff_mdct_init(&s->mdct, 9, 0, -1.0);
133 s->mdct_window = ff_ac3_window;
134 return ret;
135 }
136
137
ac3_fixed_encode_init(AVCodecContext * avctx)138 static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
139 {
140 AC3EncodeContext *s = avctx->priv_data;
141 s->fixed_point = 1;
142 return ff_ac3_encode_init(avctx);
143 }
144
145
146 AVCodec ff_ac3_fixed_encoder = {
147 .name = "ac3_fixed",
148 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
149 .type = AVMEDIA_TYPE_AUDIO,
150 .id = AV_CODEC_ID_AC3,
151 .priv_data_size = sizeof(AC3EncodeContext),
152 .init = ac3_fixed_encode_init,
153 .encode2 = ff_ac3_fixed_encode_frame,
154 .close = ff_ac3_encode_close,
155 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16P,
156 AV_SAMPLE_FMT_NONE },
157 .priv_class = &ac3enc_class,
158 .supported_samplerates = ff_ac3_sample_rate_tab,
159 .channel_layouts = ff_ac3_channel_layouts,
160 .defaults = ac3_defaults,
161 };
162