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 39static 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 */ 54av_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 */ 66av_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 */ 78static 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 */ 92static 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 105static 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 */ 115static 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 */ 125static 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 138static 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 146AVCodec 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}; 161