1/* 2 * MOFLEX Fast Audio decoder 3 * Copyright (c) 2015-2016 Florian Nouwt 4 * Copyright (c) 2017 Adib Surani 5 * Copyright (c) 2020 Paul B Mahol 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#include "libavutil/intreadwrite.h" 25 26#include "avcodec.h" 27#include "bytestream.h" 28#include "codec_internal.h" 29#include "internal.h" 30#include "mathops.h" 31 32typedef struct ChannelItems { 33 float f[8]; 34 float last; 35} ChannelItems; 36 37typedef struct FastAudioContext { 38 float table[8][64]; 39 40 ChannelItems *ch; 41} FastAudioContext; 42 43static av_cold int fastaudio_init(AVCodecContext *avctx) 44{ 45 FastAudioContext *s = avctx->priv_data; 46 47 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP; 48 49 for (int i = 0; i < 8; i++) 50 s->table[0][i] = (i - 159.5f) / 160.f; 51 for (int i = 0; i < 11; i++) 52 s->table[0][i + 8] = (i - 37.5f) / 40.f; 53 for (int i = 0; i < 27; i++) 54 s->table[0][i + 8 + 11] = (i - 13.f) / 20.f; 55 for (int i = 0; i < 11; i++) 56 s->table[0][i + 8 + 11 + 27] = (i + 27.5f) / 40.f; 57 for (int i = 0; i < 7; i++) 58 s->table[0][i + 8 + 11 + 27 + 11] = (i + 152.5f) / 160.f; 59 60 memcpy(s->table[1], s->table[0], sizeof(s->table[0])); 61 62 for (int i = 0; i < 7; i++) 63 s->table[2][i] = (i - 33.5f) / 40.f; 64 for (int i = 0; i < 25; i++) 65 s->table[2][i + 7] = (i - 13.f) / 20.f; 66 67 for (int i = 0; i < 32; i++) 68 s->table[3][i] = -s->table[2][31 - i]; 69 70 for (int i = 0; i < 16; i++) 71 s->table[4][i] = i * 0.22f / 3.f - 0.6f; 72 73 for (int i = 0; i < 16; i++) 74 s->table[5][i] = i * 0.20f / 3.f - 0.3f; 75 76 for (int i = 0; i < 8; i++) 77 s->table[6][i] = i * 0.36f / 3.f - 0.4f; 78 79 for (int i = 0; i < 8; i++) 80 s->table[7][i] = i * 0.34f / 3.f - 0.2f; 81 82 s->ch = av_calloc(avctx->ch_layout.nb_channels, sizeof(*s->ch)); 83 if (!s->ch) 84 return AVERROR(ENOMEM); 85 86 return 0; 87} 88 89static int read_bits(int bits, int *ppos, unsigned *src) 90{ 91 int r, pos; 92 93 pos = *ppos; 94 pos += bits; 95 r = src[(pos - 1) / 32] >> ((-pos) & 31); 96 *ppos = pos; 97 98 return r & ((1 << bits) - 1); 99} 100 101static const uint8_t bits[8] = { 6, 6, 5, 5, 4, 0, 3, 3, }; 102 103static void set_sample(int i, int j, int v, float *result, int *pads, float value) 104{ 105 result[i * 64 + pads[i] + j * 3] = value * (2 * v - 7); 106} 107 108static int fastaudio_decode(AVCodecContext *avctx, AVFrame *frame, 109 int *got_frame, AVPacket *pkt) 110{ 111 FastAudioContext *s = avctx->priv_data; 112 GetByteContext gb; 113 int subframes; 114 int ret; 115 116 subframes = pkt->size / (40 * avctx->ch_layout.nb_channels); 117 frame->nb_samples = subframes * 256; 118 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) 119 return ret; 120 121 bytestream2_init(&gb, pkt->data, pkt->size); 122 123 for (int subframe = 0; subframe < subframes; subframe++) { 124 for (int channel = 0; channel < avctx->ch_layout.nb_channels; channel++) { 125 ChannelItems *ch = &s->ch[channel]; 126 float result[256] = { 0 }; 127 unsigned src[10]; 128 int inds[4], pads[4]; 129 float m[8]; 130 int pos = 0; 131 132 for (int i = 0; i < 10; i++) 133 src[i] = bytestream2_get_le32(&gb); 134 135 for (int i = 0; i < 8; i++) 136 m[7 - i] = s->table[i][read_bits(bits[i], &pos, src)]; 137 138 for (int i = 0; i < 4; i++) 139 inds[3 - i] = read_bits(6, &pos, src); 140 141 for (int i = 0; i < 4; i++) 142 pads[3 - i] = read_bits(2, &pos, src); 143 144 for (int i = 0, index5 = 0; i < 4; i++) { 145 float value = av_int2float((inds[i] + 1) << 20) * powf(2.f, 116.f); 146 147 for (int j = 0, tmp = 0; j < 21; j++) { 148 set_sample(i, j, j == 20 ? tmp / 2 : read_bits(3, &pos, src), result, pads, value); 149 if (j % 10 == 9) 150 tmp = 4 * tmp + read_bits(2, &pos, src); 151 if (j == 20) 152 index5 = FFMIN(2 * index5 + tmp % 2, 63); 153 } 154 155 m[2] = s->table[5][index5]; 156 } 157 158 for (int i = 0; i < 256; i++) { 159 float x = result[i]; 160 161 for (int j = 0; j < 8; j++) { 162 x -= m[j] * ch->f[j]; 163 ch->f[j] += m[j] * x; 164 } 165 166 memmove(&ch->f[0], &ch->f[1], sizeof(float) * 7); 167 ch->f[7] = x; 168 ch->last = x + ch->last * 0.86f; 169 result[i] = ch->last * 2.f; 170 } 171 172 memcpy(frame->extended_data[channel] + 1024 * subframe, result, 256 * sizeof(float)); 173 } 174 } 175 176 *got_frame = 1; 177 178 return pkt->size; 179} 180 181static av_cold int fastaudio_close(AVCodecContext *avctx) 182{ 183 FastAudioContext *s = avctx->priv_data; 184 185 av_freep(&s->ch); 186 187 return 0; 188} 189 190const FFCodec ff_fastaudio_decoder = { 191 .p.name = "fastaudio", 192 .p.long_name = NULL_IF_CONFIG_SMALL("MobiClip FastAudio"), 193 .p.type = AVMEDIA_TYPE_AUDIO, 194 .p.id = AV_CODEC_ID_FASTAUDIO, 195 .priv_data_size = sizeof(FastAudioContext), 196 .init = fastaudio_init, 197 FF_CODEC_DECODE_CB(fastaudio_decode), 198 .close = fastaudio_close, 199 .p.capabilities = AV_CODEC_CAP_DR1, 200 .p.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP, 201 AV_SAMPLE_FMT_NONE }, 202 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE, 203}; 204