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>
7 * This file is part of FFmpeg.
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.
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.
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
26 * fixed-point AC-3 encoder.
29 #define AC3ENC_FLOAT 0
31 #define FFT_FIXED_32 1
38 static const AVClass ac3enc_class = {
39 .class_name = "Fixed-Point AC-3 Encoder",
40 .item_name = av_default_item_name,
41 .option = ff_ac3_enc_options,
42 .version = LIBAVUTIL_VERSION_INT,
45 static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4],
46 const int32_t *coef0, const int32_t *coef1,
49 s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1, len);
53 * Clip MDCT coefficients to allowable range.
55 static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef,
58 adsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
63 * Calculate a single coupling coordinate.
65 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
67 if (energy_cpl <= COEF_MAX) {
70 uint64_t coord = energy_ch / (energy_cpl >> 24);
71 uint32_t coord32 = FFMIN(coord, 1073741824);
72 coord32 = ff_sqrt(coord32) << 9;
73 return FFMIN(coord32, COEF_MAX);
78 #include "ac3enc_template.c"
82 * Finalize MDCT and free allocated memory.
84 * @param s AC-3 encoder private context
86 static av_cold void ac3_fixed_mdct_end(AC3EncodeContext *s)
88 ff_mdct_end(&s->mdct);
92 * Initialize MDCT tables.
94 * @param s AC-3 encoder private context
95 * @return 0 on success, negative error code on failure
97 static av_cold int ac3_fixed_mdct_init(AC3EncodeContext *s)
99 float fwin[AC3_BLOCK_SIZE];
101 int32_t *iwin = av_malloc_array(AC3_BLOCK_SIZE, sizeof(*iwin));
103 return AVERROR(ENOMEM);
105 ff_kbd_window_init(fwin, 5.0, AC3_BLOCK_SIZE);
106 for (int i = 0; i < AC3_BLOCK_SIZE; i++)
107 iwin[i] = lrintf(fwin[i] * (1 << 22));
109 s->mdct_window = iwin;
111 s->fdsp = avpriv_alloc_fixed_dsp(s->avctx->flags & AV_CODEC_FLAG_BITEXACT);
113 return AVERROR(ENOMEM);
115 return ff_mdct_init(&s->mdct, 9, 0, -1.0);
119 static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
121 AC3EncodeContext *s = avctx->priv_data;
123 s->mdct_end = ac3_fixed_mdct_end;
124 s->mdct_init = ac3_fixed_mdct_init;
125 s->allocate_sample_buffers = allocate_sample_buffers;
126 return ff_ac3_encode_init(avctx);
130 AVCodec ff_ac3_fixed_encoder = {
132 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
133 .type = AVMEDIA_TYPE_AUDIO,
134 .id = AV_CODEC_ID_AC3,
135 .priv_data_size = sizeof(AC3EncodeContext),
136 .init = ac3_fixed_encode_init,
137 .encode2 = ff_ac3_fixed_encode_frame,
138 .close = ff_ac3_encode_close,
139 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32P,
140 AV_SAMPLE_FMT_NONE },
141 .priv_class = &ac3enc_class,
142 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
143 .supported_samplerates = ff_ac3_sample_rate_tab,
144 .channel_layouts = ff_ac3_channel_layouts,
145 .defaults = ff_ac3_enc_defaults,