FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/ac3enc_fixed.c
Date: 2026-09-07 08:47:58
Exec Total Coverage
Lines: 29 31 93.5%
Functions: 5 5 100.0%
Branches: 6 8 75.0%

Line Branch Exec Source
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 AC3ENC_FLOAT 0
30 #include "audiodsp.h"
31 #include "ac3enc.h"
32 #include "codec_internal.h"
33 #include "eac3enc.h"
34 #include "kbdwin.h"
35
36 12672 static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4],
37 const int32_t *coef0, const int32_t *coef1,
38 int len)
39 {
40 12672 s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len);
41 12672 }
42
43 /*
44 * Clip MDCT coefficients to allowable range.
45 */
46 1512 static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef,
47 unsigned int len)
48 {
49 1512 adsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
50 1512 }
51
52
53 /*
54 * Calculate a single coupling coordinate.
55 */
56 14932 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
57 {
58
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14932 if (energy_cpl <= COEF_MAX) {
59 10860 return 1048576;
60 } else {
61 4072 uint64_t coord = energy_ch / (energy_cpl >> 24);
62 4072 uint32_t coord32 = FFMIN(coord, 1073741824);
63 4072 coord32 = ff_sqrt(coord32) << 9;
64 4072 return FFMIN(coord32, COEF_MAX);
65 }
66 }
67
68 #include "ac3enc_template.c"
69
70 /**
71 * Initialize MDCT tables.
72 *
73 * @param s AC-3 encoder private context
74 * @return 0 on success, negative error code on failure
75 */
76 12 static av_cold int ac3_fixed_mdct_init(AVCodecContext *avctx, AC3EncodeContext *s)
77 {
78 float fwin[AC3_BLOCK_SIZE];
79 12 const float scale = -1.0f;
80
81 12 int32_t *iwin = s->mdct_window_fixed;
82
83 12 ff_kbd_window_init(fwin, 5.0, AC3_BLOCK_SIZE);
84
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3084 for (int i = 0; i < AC3_BLOCK_SIZE; i++)
85 3072 iwin[i] = lrintf(fwin[i] * (1 << 22));
86
87 12 s->fdsp = avpriv_alloc_fixed_dsp(avctx->flags & AV_CODEC_FLAG_BITEXACT);
88
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12 if (!s->fdsp)
89 return AVERROR(ENOMEM);
90
91 12 return av_tx_init(&s->tx, &s->tx_fn, AV_TX_INT32_MDCT, 0,
92 AC3_BLOCK_SIZE, &scale, 0);
93 }
94
95
96 12 static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
97 {
98 12 AC3EncodeContext *s = avctx->priv_data;
99 int ret;
100
101 12 s->fixed_point = 1;
102 12 s->encode_frame = encode_frame;
103
104 12 ret = ac3_fixed_mdct_init(avctx, s);
105
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12 if (ret < 0)
106 return ret;
107
108 12 return ff_ac3_encode_init(avctx);
109 }
110
111
112 const FFCodec ff_ac3_fixed_encoder = {
113 .p.name = "ac3_fixed",
114 CODEC_LONG_NAME("ATSC A/52A (AC-3)"),
115 .p.type = AVMEDIA_TYPE_AUDIO,
116 .p.id = AV_CODEC_ID_AC3,
117 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY |
118 AV_CODEC_CAP_SMALL_LAST_FRAME | AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
119 .priv_data_size = sizeof(AC3EncodeContext),
120 .init = ac3_fixed_encode_init,
121 FF_CODEC_ENCODE_CB(ff_ac3_encode_frame),
122 .close = ff_ac3_encode_close,
123 CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_S32P),
124 .p.priv_class = &ff_ac3enc_class,
125 .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
126 CODEC_SAMPLERATES_ARRAY(ff_ac3_sample_rate_tab),
127 CODEC_CH_LAYOUTS_ARRAY(ff_ac3_ch_layouts),
128 .defaults = ff_ac3_enc_defaults,
129 };
130