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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 | #include "ac3enc_template.c" | |
47 | ||
48 | ||
49 | /** | |
50 | * Finalize MDCT and free allocated memory. | |
51 | * | |
52 | * @param s AC-3 encoder private context | |
53 | */ | |
54 | av_cold void AC3_NAME(mdct_end)(AC3EncodeContext *s) | |
55 | { | |
56 | ff_mdct_end(&s->mdct); | |
57 | } | |
58 | ||
59 | ||
60 | /** | |
61 | * Initialize MDCT tables. | |
62 | * | |
63 | * @param s AC-3 encoder private context | |
64 | * @return 0 on success, negative error code on failure | |
65 | */ | |
66 | av_cold int AC3_NAME(mdct_init)(AC3EncodeContext *s) | |
67 | { | |
68 | int ret = ff_mdct_init(&s->mdct, 9, 0, -1.0); | |
69 | s->mdct_window = ff_ac3_window; | |
70 | return ret; | |
71 | } | |
72 | ||
73 | ||
74 | /* | |
75 | * Normalize the input samples to use the maximum available precision. | |
76 | * This assumes signed 16-bit input samples. | |
77 | */ | |
78 | static int normalize_samples(AC3EncodeContext *s) | |
79 | { | |
80 | int v = s->ac3dsp.ac3_max_msb_abs_int16(s->windowed_samples, AC3_WINDOW_SIZE); | |
81 | v = 14 - av_log2(v); | |
82 | if (v > 0) | |
83 | s->ac3dsp.ac3_lshift_int16(s->windowed_samples, AC3_WINDOW_SIZE, v); | |
84 | /* +6 to right-shift from 31-bit to 25-bit */ | |
85 | return v + 6; | |
86 | } | |
87 | ||
88 | ||
89 | /* | |
90 | * Scale MDCT coefficients to 25-bit signed fixed-point. | |
91 | */ | |
92 | static void scale_coefficients(AC3EncodeContext *s) | |
93 | { | |
94 | int blk, ch; | |
95 | ||
96 | for (blk = 0; blk < s->num_blocks; blk++) { | |
97 | AC3Block *block = &s->blocks[blk]; | |
98 | for (ch = 1; ch <= s->channels; ch++) { | |
99 | s->ac3dsp.ac3_rshift_int32(block->mdct_coef[ch], AC3_MAX_COEFS, | |
100 | block->coeff_shift[ch]); | |
101 | } | |
102 | } | |
103 | } | |
104 | ||
105 | static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4], | |
106 | const int32_t *coef0, const int32_t *coef1, | |
107 | int len) | |
108 | { | |
109 | s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len); | |
110 | } | |
111 | ||
112 | /* | |
113 | * Clip MDCT coefficients to allowable range. | |
114 | */ | |
115 | static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef, | |
116 | unsigned int len) | |
117 | { | |
118 | adsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len); | |
119 | } | |
120 | ||
121 | ||
122 | /* | |
123 | * Calculate a single coupling coordinate. | |
124 | */ | |
125 | static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl) | |
126 | { | |
127 | if (energy_cpl <= COEF_MAX) { | |
128 | return 1048576; | |
129 | } else { | |
130 | uint64_t coord = energy_ch / (energy_cpl >> 24); | |
131 | uint32_t coord32 = FFMIN(coord, 1073741824); | |
132 | coord32 = ff_sqrt(coord32) << 9; | |
133 | return FFMIN(coord32, COEF_MAX); | |
134 | } | |
135 | } | |
136 | ||
137 | ||
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 | .channel_layouts = ff_ac3_channel_layouts, | |
159 | .defaults = ac3_defaults, | |
160 | }; |