1/* 2 * FLAC common code 3 * Copyright (c) 2009 Justin Ruggles 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#include "libavutil/channel_layout.h" 23#include "libavutil/crc.h" 24#include "libavutil/log.h" 25#include "bytestream.h" 26#include "get_bits.h" 27#include "flac.h" 28#include "flacdata.h" 29 30static const int8_t sample_size_table[] = { 0, 8, 12, 0, 16, 20, 24, 0 }; 31 32static const AVChannelLayout flac_channel_layouts[8] = { 33 AV_CHANNEL_LAYOUT_MONO, 34 AV_CHANNEL_LAYOUT_STEREO, 35 AV_CHANNEL_LAYOUT_SURROUND, 36 AV_CHANNEL_LAYOUT_QUAD, 37 AV_CHANNEL_LAYOUT_5POINT0, 38 AV_CHANNEL_LAYOUT_5POINT1, 39 AV_CHANNEL_LAYOUT_6POINT1, 40 AV_CHANNEL_LAYOUT_7POINT1 41}; 42 43static int64_t get_utf8(GetBitContext *gb) 44{ 45 int64_t val; 46 GET_UTF8(val, get_bits(gb, 8), return -1;) 47 return val; 48} 49 50int ff_flac_decode_frame_header(AVCodecContext *avctx, GetBitContext *gb, 51 FLACFrameInfo *fi, int log_level_offset) 52{ 53 int bs_code, sr_code, bps_code; 54 55 /* frame sync code */ 56 if ((get_bits(gb, 15) & 0x7FFF) != 0x7FFC) { 57 av_log(avctx, AV_LOG_ERROR + log_level_offset, "invalid sync code\n"); 58 return AVERROR_INVALIDDATA; 59 } 60 61 /* variable block size stream code */ 62 fi->is_var_size = get_bits1(gb); 63 64 /* block size and sample rate codes */ 65 bs_code = get_bits(gb, 4); 66 sr_code = get_bits(gb, 4); 67 68 /* channels and decorrelation */ 69 fi->ch_mode = get_bits(gb, 4); 70 if (fi->ch_mode < FLAC_MAX_CHANNELS) { 71 fi->channels = fi->ch_mode + 1; 72 fi->ch_mode = FLAC_CHMODE_INDEPENDENT; 73 } else if (fi->ch_mode < FLAC_MAX_CHANNELS + FLAC_CHMODE_MID_SIDE) { 74 fi->channels = 2; 75 fi->ch_mode -= FLAC_MAX_CHANNELS - 1; 76 } else { 77 av_log(avctx, AV_LOG_ERROR + log_level_offset, 78 "invalid channel mode: %d\n", fi->ch_mode); 79 return AVERROR_INVALIDDATA; 80 } 81 82 /* bits per sample */ 83 bps_code = get_bits(gb, 3); 84 if (bps_code == 3 || bps_code == 7) { 85 av_log(avctx, AV_LOG_ERROR + log_level_offset, 86 "invalid sample size code (%d)\n", 87 bps_code); 88 return AVERROR_INVALIDDATA; 89 } 90 fi->bps = sample_size_table[bps_code]; 91 92 /* reserved bit */ 93 if (get_bits1(gb)) { 94 av_log(avctx, AV_LOG_ERROR + log_level_offset, 95 "broken stream, invalid padding\n"); 96 return AVERROR_INVALIDDATA; 97 } 98 99 /* sample or frame count */ 100 fi->frame_or_sample_num = get_utf8(gb); 101 if (fi->frame_or_sample_num < 0) { 102 av_log(avctx, AV_LOG_ERROR + log_level_offset, 103 "sample/frame number invalid; utf8 fscked\n"); 104 return AVERROR_INVALIDDATA; 105 } 106 107 /* blocksize */ 108 if (bs_code == 0) { 109 av_log(avctx, AV_LOG_ERROR + log_level_offset, 110 "reserved blocksize code: 0\n"); 111 return AVERROR_INVALIDDATA; 112 } else if (bs_code == 6) { 113 fi->blocksize = get_bits(gb, 8) + 1; 114 } else if (bs_code == 7) { 115 fi->blocksize = get_bits(gb, 16) + 1; 116 } else { 117 fi->blocksize = ff_flac_blocksize_table[bs_code]; 118 } 119 120 /* sample rate */ 121 if (sr_code < 12) { 122 fi->samplerate = ff_flac_sample_rate_table[sr_code]; 123 } else if (sr_code == 12) { 124 fi->samplerate = get_bits(gb, 8) * 1000; 125 } else if (sr_code == 13) { 126 fi->samplerate = get_bits(gb, 16); 127 } else if (sr_code == 14) { 128 fi->samplerate = get_bits(gb, 16) * 10; 129 } else { 130 av_log(avctx, AV_LOG_ERROR + log_level_offset, 131 "illegal sample rate code %d\n", 132 sr_code); 133 return AVERROR_INVALIDDATA; 134 } 135 136 /* header CRC-8 check */ 137 skip_bits(gb, 8); 138 if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer, 139 get_bits_count(gb)/8)) { 140 av_log(avctx, AV_LOG_ERROR + log_level_offset, 141 "header crc mismatch\n"); 142 return AVERROR_INVALIDDATA; 143 } 144 145 return 0; 146} 147 148int ff_flac_get_max_frame_size(int blocksize, int ch, int bps) 149{ 150 /* Technically, there is no limit to FLAC frame size, but an encoder 151 should not write a frame that is larger than if verbatim encoding mode 152 were to be used. */ 153 154 int count; 155 156 count = 16; /* frame header */ 157 count += ch * ((7+bps+7)/8); /* subframe headers */ 158 if (ch == 2) { 159 /* for stereo, need to account for using decorrelation */ 160 count += (( 2*bps+1) * blocksize + 7) / 8; 161 } else { 162 count += ( ch*bps * blocksize + 7) / 8; 163 } 164 count += 2; /* frame footer */ 165 166 return count; 167} 168 169int ff_flac_is_extradata_valid(AVCodecContext *avctx, 170 enum FLACExtradataFormat *format, 171 uint8_t **streaminfo_start) 172{ 173 if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) { 174 av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n"); 175 return 0; 176 } 177 if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) { 178 /* extradata contains STREAMINFO only */ 179 if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) { 180 av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n", 181 FLAC_STREAMINFO_SIZE-avctx->extradata_size); 182 } 183 *format = FLAC_EXTRADATA_FORMAT_STREAMINFO; 184 *streaminfo_start = avctx->extradata; 185 } else { 186 if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) { 187 av_log(avctx, AV_LOG_ERROR, "extradata too small.\n"); 188 return 0; 189 } 190 *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER; 191 *streaminfo_start = &avctx->extradata[8]; 192 } 193 return 1; 194} 195 196void ff_flac_set_channel_layout(AVCodecContext *avctx, int channels) 197{ 198 if (channels == avctx->ch_layout.nb_channels && 199 avctx->ch_layout.order != AV_CHANNEL_ORDER_UNSPEC) 200 return; 201 202 av_channel_layout_uninit(&avctx->ch_layout); 203 if (channels <= FF_ARRAY_ELEMS(flac_channel_layouts)) 204 avctx->ch_layout = flac_channel_layouts[channels - 1]; 205 else 206 avctx->ch_layout = (AVChannelLayout){ .order = AV_CHANNEL_ORDER_UNSPEC, 207 .nb_channels = channels }; 208} 209 210int ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s, 211 const uint8_t *buffer) 212{ 213 GetBitContext gb; 214 init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8); 215 216 skip_bits(&gb, 16); /* skip min blocksize */ 217 s->max_blocksize = get_bits(&gb, 16); 218 if (s->max_blocksize < FLAC_MIN_BLOCKSIZE) { 219 av_log(avctx, AV_LOG_WARNING, "invalid max blocksize: %d\n", 220 s->max_blocksize); 221 s->max_blocksize = 16; 222 return AVERROR_INVALIDDATA; 223 } 224 225 skip_bits(&gb, 24); /* skip min frame size */ 226 s->max_framesize = get_bits(&gb, 24); 227 228 s->samplerate = get_bits(&gb, 20); 229 s->channels = get_bits(&gb, 3) + 1; 230 s->bps = get_bits(&gb, 5) + 1; 231 232 if (s->bps < 4) { 233 av_log(avctx, AV_LOG_ERROR, "invalid bps: %d\n", s->bps); 234 s->bps = 16; 235 return AVERROR_INVALIDDATA; 236 } 237 238 avctx->sample_rate = s->samplerate; 239 avctx->bits_per_raw_sample = s->bps; 240 ff_flac_set_channel_layout(avctx, s->channels); 241 242 s->samples = get_bits64(&gb, 36); 243 244 skip_bits_long(&gb, 64); /* md5 sum */ 245 skip_bits_long(&gb, 64); /* md5 sum */ 246 247 return 0; 248} 249