| 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 | }; |