FFmpeg: libavformat/cafdec.c Source File

FFmpeg

[フレーム]

libavformat

cafdec.c

Go to the documentation of this file.

1 /*

2 * Core Audio Format demuxer

5 *

6 * This file is part of FFmpeg.

7 *

8 * FFmpeg is free software; you can redistribute it and/or

9 * modify it under the terms of the GNU Lesser General Public

10 * License as published by the Free Software Foundation; either

11 * version 2.1 of the License, or (at your option) any later version.

12 *

13 * FFmpeg is distributed in the hope that it will be useful,

14 * but WITHOUT ANY WARRANTY; without even the implied warranty of

15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

16 * Lesser General Public License for more details.

17 *

18 * You should have received a copy of the GNU Lesser General Public

19 * License along with FFmpeg; if not, write to the Free Software

20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

21 */

23 /**

24 * @file

25 * Core Audio Format demuxer

26 */

28 #include <inttypes.h>

30 #include "avformat.h"

31 #include "internal.h"

32 #include "isom.h"

33 #include "mov_chan.h"

34 #include "libavutil/intreadwrite.h"

35 #include "libavutil/intfloat.h"

36 #include "libavutil/dict.h"

37 #include "caf.h"

39 typedef struct CafContext {

40 int bytes_per_packet; ///< bytes in a packet, or 0 if variable

41 int frames_per_packet; ///< frames in a packet, or 0 if variable

42 int64_t num_bytes; ///< total number of bytes in stream

44 int64_t packet_cnt; ///< packet counter

45 int64_t frame_cnt; ///< frame counter

47 int64_t data_start; ///< data start position, in bytes

48 int64_t data_size; ///< raw data size, in bytes

49 } CafContext;

51 static int probe(AVProbeData *p)

52 {

53 if (AV_RB32(p->buf) == MKBETAG('c','a','f','f') && AV_RB16(&p->buf[4]) == 1)

54 return AVPROBE_SCORE_MAX;

55 return 0;

56 }

58 /** Read audio description chunk */

59 static int read_desc_chunk(AVFormatContext *s)

60 {

61 AVIOContext *pb = s->pb;

62 CafContext *caf = s->priv_data;

63 AVStream *st;

64 int flags;

66 /* new audio stream */

67 st = avformat_new_stream(s, NULL);

68 if (!st)

69 return AVERROR(ENOMEM);

71 /* parse format description */

72 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

73 st->codec->sample_rate = av_int2double(avio_rb64(pb));

74 st->codec->codec_tag = avio_rl32(pb);

75 flags = avio_rb32(pb);

76 caf->bytes_per_packet = avio_rb32(pb);

77 st->codec->block_align = caf->bytes_per_packet;

78 caf->frames_per_packet = avio_rb32(pb);

79 st->codec->channels = avio_rb32(pb);

80 st->codec->bits_per_coded_sample = avio_rb32(pb);

82 /* calculate bit rate for constant size packets */

83 if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {

84 st->codec->bit_rate = (uint64_t)st->codec->sample_rate * (uint64_t)caf->bytes_per_packet * 8

85 / (uint64_t)caf->frames_per_packet;

86 } else {

87 st->codec->bit_rate = 0;

88 }

90 /* determine codec */

91 if (st->codec->codec_tag == MKTAG('l','p','c','m'))

92 st->codec->codec_id = ff_mov_get_lpcm_codec_id(st->codec->bits_per_coded_sample, (flags ^ 0x2) | 0x4);

93 else

94 st->codec->codec_id = ff_codec_get_id(ff_codec_caf_tags, st->codec->codec_tag);

95 return 0;

96 }

98 /** Read magic cookie chunk */

99 static int read_kuki_chunk(AVFormatContext *s, int64_t size)

100 {

101 AVIOContext *pb = s->pb;

102 AVStream *st = s->streams[0];

103

104 if (size < 0 || size > INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE)

105 return -1;

106

107 if (st->codec->codec_id == AV_CODEC_ID_AAC) {

108 /* The magic cookie format for AAC is an mp4 esds atom.

109 The lavc AAC decoder requires the data from the codec specific

110 description as extradata input. */

111 int strt, skip;

112

113 strt = avio_tell(pb);

114 ff_mov_read_esds(s, pb);

115 skip = size - (avio_tell(pb) - strt);

116 if (skip < 0 || !st->codec->extradata ||

117 st->codec->codec_id != AV_CODEC_ID_AAC) {

118 av_log(s, AV_LOG_ERROR, "invalid AAC magic cookie\n");

119 return AVERROR_INVALIDDATA;

120 }

121 avio_skip(pb, skip);

122 } else if (st->codec->codec_id == AV_CODEC_ID_ALAC) {

123 #define ALAC_PREAMBLE 12

124 #define ALAC_HEADER 36

125 #define ALAC_NEW_KUKI 24

126 uint8_t preamble[12];

127 if (size < ALAC_NEW_KUKI) {

128 av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");

129 avio_skip(pb, size);

130 return AVERROR_INVALIDDATA;

131 }

132 avio_read(pb, preamble, ALAC_PREAMBLE);

133

134 if (ff_alloc_extradata(st->codec, ALAC_HEADER))

135 return AVERROR(ENOMEM);

136

137 /* For the old style cookie, we skip 12 bytes, then read 36 bytes.

138 * The new style cookie only contains the last 24 bytes of what was

139 * 36 bytes in the old style cookie, so we fabricate the first 12 bytes

140 * in that case to maintain compatibility. */

141 if (!memcmp(&preamble[4], "frmaalac", 8)) {

142 if (size < ALAC_PREAMBLE + ALAC_HEADER) {

143 av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");

144 av_freep(&st->codec->extradata);

145 return AVERROR_INVALIDDATA;

146 }

147 avio_read(pb, st->codec->extradata, ALAC_HEADER);

148 avio_skip(pb, size - ALAC_PREAMBLE - ALAC_HEADER);

149 } else {

150 AV_WB32(st->codec->extradata, 36);

151 memcpy(&st->codec->extradata[4], "alac", 4);

152 AV_WB32(&st->codec->extradata[8], 0);

153 memcpy(&st->codec->extradata[12], preamble, 12);

154 avio_read(pb, &st->codec->extradata[24], ALAC_NEW_KUKI - 12);

155 avio_skip(pb, size - ALAC_NEW_KUKI);

156 }

157 } else {

158 if (ff_get_extradata(st->codec, pb, size) < 0)

159 return AVERROR(ENOMEM);

160 }

161

162 return 0;

163 }

164

165 /** Read packet table chunk */

166 static int read_pakt_chunk(AVFormatContext *s, int64_t size)

167 {

168 AVIOContext *pb = s->pb;

169 AVStream *st = s->streams[0];

170 CafContext *caf = s->priv_data;

171 int64_t pos = 0, ccount, num_packets;

172 int i;

173

174 ccount = avio_tell(pb);

175

176 num_packets = avio_rb64(pb);

177 if (num_packets < 0 || INT32_MAX / sizeof(AVIndexEntry) < num_packets)

178 return AVERROR_INVALIDDATA;

179

180 st->nb_frames = avio_rb64(pb); /* valid frames */

181 st->nb_frames += avio_rb32(pb); /* priming frames */

182 st->nb_frames += avio_rb32(pb); /* remainder frames */

183

184 st->duration = 0;

185 for (i = 0; i < num_packets; i++) {

186 av_add_index_entry(s->streams[0], pos, st->duration, 0, 0, AVINDEX_KEYFRAME);

187 pos += caf->bytes_per_packet ? caf->bytes_per_packet : ff_mp4_read_descr_len(pb);

188 st->duration += caf->frames_per_packet ? caf->frames_per_packet : ff_mp4_read_descr_len(pb);

189 }

190

191 if (avio_tell(pb) - ccount > size) {

192 av_log(s, AV_LOG_ERROR, "error reading packet table\n");

193 return AVERROR_INVALIDDATA;

194 }

195 avio_skip(pb, ccount + size - avio_tell(pb));

196

197 caf->num_bytes = pos;

198 return 0;

199 }

200

201 /** Read information chunk */

202 static void read_info_chunk(AVFormatContext *s, int64_t size)

203 {

204 AVIOContext *pb = s->pb;

205 unsigned int i;

206 unsigned int nb_entries = avio_rb32(pb);

207 for (i = 0; i < nb_entries && !avio_feof(pb); i++) {

208 char key[32];

209 char value[1024];

210 avio_get_str(pb, INT_MAX, key, sizeof(key));

211 avio_get_str(pb, INT_MAX, value, sizeof(value));

212 av_dict_set(&s->metadata, key, value, 0);

213 }

214 }

215

216 static int read_header(AVFormatContext *s)

217 {

218 AVIOContext *pb = s->pb;

219 CafContext *caf = s->priv_data;

220 AVStream *st;

221 uint32_t tag = 0;

222 int found_data, ret;

223 int64_t size, pos;

224

225 avio_skip(pb, 8); /* magic, version, file flags */

226

227 /* audio description chunk */

228 if (avio_rb32(pb) != MKBETAG('d','e','s','c')) {

229 av_log(s, AV_LOG_ERROR, "desc chunk not present\n");

230 return AVERROR_INVALIDDATA;

231 }

232 size = avio_rb64(pb);

233 if (size != 32)

234 return AVERROR_INVALIDDATA;

235

236 ret = read_desc_chunk(s);

237 if (ret)

238 return ret;

239 st = s->streams[0];

240

241 /* parse each chunk */

242 found_data = 0;

243 while (!avio_feof(pb)) {

244

245 /* stop at data chunk if seeking is not supported or

246 data chunk size is unknown */

247 if (found_data && (caf->data_size < 0 || !pb->seekable))

248 break;

249

250 tag = avio_rb32(pb);

251 size = avio_rb64(pb);

252 pos = avio_tell(pb);

253 if (avio_feof(pb))

254 break;

255

256 switch (tag) {

257 case MKBETAG('d','a','t','a'):

258 avio_skip(pb, 4); /* edit count */

259 caf->data_start = avio_tell(pb);

260 caf->data_size = size < 0 ? -1 : size - 4;

261 if (caf->data_size > 0 && pb->seekable)

262 avio_skip(pb, caf->data_size);

263 found_data = 1;

264 break;

265

266 case MKBETAG('c','h','a','n'):

267 if ((ret = ff_mov_read_chan(s, s->pb, st, size)) < 0)

268 return ret;

269 break;

270

271 /* magic cookie chunk */

272 case MKBETAG('k','u','k','i'):

273 if (read_kuki_chunk(s, size))

274 return AVERROR_INVALIDDATA;

275 break;

276

277 /* packet table chunk */

278 case MKBETAG('p','a','k','t'):

279 if (read_pakt_chunk(s, size))

280 return AVERROR_INVALIDDATA;

281 break;

282

283 case MKBETAG('i','n','f','o'):

284 read_info_chunk(s, size);

285 break;

286

287 default:

288 #define _(x) ((x) >= ' ' ? (x) : ' ')

289 av_log(s, AV_LOG_WARNING,

290 "skipping CAF chunk: %08"PRIX32" (%c%c%c%c), size %"PRId64"\n",

291 tag, _(tag>>24), _((tag>>16)&0xFF), _((tag>>8)&0xFF), _(tag&0xFF), size);

292 #undef _

293 case MKBETAG('f','r','e','e'):

294 if (size < 0)

295 return AVERROR_INVALIDDATA;

296 break;

297 }

298

299 if (size > 0) {

300 if (pos > INT64_MAX - size)

301 return AVERROR_INVALIDDATA;

302 avio_skip(pb, FFMAX(0, pos + size - avio_tell(pb)));

303 }

304 }

305

306 if (!found_data)

307 return AVERROR_INVALIDDATA;

308

309 if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {

310 if (caf->data_size > 0)

311 st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;

312 } else if (st->nb_index_entries && st->duration > 0) {

313 st->codec->bit_rate = st->codec->sample_rate * caf->data_size * 8 /

314 st->duration;

315 } else {

316 av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "

317 "block size or frame size are variable.\n");

318 return AVERROR_INVALIDDATA;

319 }

320

321 avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);

322 st->start_time = 0;

323

324 /* position the stream at the start of data */

325 if (caf->data_size >= 0)

326 avio_seek(pb, caf->data_start, SEEK_SET);

327

328 return 0;

329 }

330

331 #define CAF_MAX_PKT_SIZE 4096

332

333 static int read_packet(AVFormatContext *s, AVPacket *pkt)

334 {

335 AVIOContext *pb = s->pb;

336 AVStream *st = s->streams[0];

337 CafContext *caf = s->priv_data;

338 int res, pkt_size = 0, pkt_frames = 0;

339 int64_t left = CAF_MAX_PKT_SIZE;

340

341 if (avio_feof(pb))

342 return AVERROR_EOF;

343

344 /* don't read past end of data chunk */

345 if (caf->data_size > 0) {

346 left = (caf->data_start + caf->data_size) - avio_tell(pb);

347 if (!left)

348 return AVERROR_EOF;

349 if (left < 0)

350 return AVERROR(EIO);

351 }

352

353 pkt_frames = caf->frames_per_packet;

354 pkt_size = caf->bytes_per_packet;

355

356 if (pkt_size > 0 && pkt_frames == 1) {

357 pkt_size = (CAF_MAX_PKT_SIZE / pkt_size) * pkt_size;

358 pkt_size = FFMIN(pkt_size, left);

359 pkt_frames = pkt_size / caf->bytes_per_packet;

360 } else if (st->nb_index_entries) {

361 if (caf->packet_cnt < st->nb_index_entries - 1) {

362 pkt_size = st->index_entries[caf->packet_cnt + 1].pos - st->index_entries[caf->packet_cnt].pos;

363 pkt_frames = st->index_entries[caf->packet_cnt + 1].timestamp - st->index_entries[caf->packet_cnt].timestamp;

364 } else if (caf->packet_cnt == st->nb_index_entries - 1) {

365 pkt_size = caf->num_bytes - st->index_entries[caf->packet_cnt].pos;

366 pkt_frames = st->duration - st->index_entries[caf->packet_cnt].timestamp;

367 } else {

368 return AVERROR(EIO);

369 }

370 }

371

372 if (pkt_size == 0 || pkt_frames == 0 || pkt_size > left)

373 return AVERROR(EIO);

374

375 res = av_get_packet(pb, pkt, pkt_size);

376 if (res < 0)

377 return res;

378

379 pkt->size = res;

380 pkt->stream_index = 0;

381 pkt->dts = pkt->pts = caf->frame_cnt;

382

383 caf->packet_cnt++;

384 caf->frame_cnt += pkt_frames;

385

386 return 0;

387 }

388

389 static int read_seek(AVFormatContext *s, int stream_index,

390 int64_t timestamp, int flags)

391 {

392 AVStream *st = s->streams[0];

393 CafContext *caf = s->priv_data;

394 int64_t pos, packet_cnt, frame_cnt;

395

396 timestamp = FFMAX(timestamp, 0);

397

398 if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {

399 /* calculate new byte position based on target frame position */

400 pos = caf->bytes_per_packet * (timestamp / caf->frames_per_packet);

401 if (caf->data_size > 0)

402 pos = FFMIN(pos, caf->data_size);

403 packet_cnt = pos / caf->bytes_per_packet;

404 frame_cnt = caf->frames_per_packet * packet_cnt;

405 } else if (st->nb_index_entries) {

406 packet_cnt = av_index_search_timestamp(st, timestamp, flags);

407 frame_cnt = st->index_entries[packet_cnt].timestamp;

408 pos = st->index_entries[packet_cnt].pos;

409 } else {

410 return -1;

411 }

412

413 if (avio_seek(s->pb, pos + caf->data_start, SEEK_SET) < 0)

414 return -1;

415

416 caf->packet_cnt = packet_cnt;

417 caf->frame_cnt = frame_cnt;

418

419 return 0;

420 }

421

422 AVInputFormat ff_caf_demuxer = {

423 .name = "caf",

424 .long_name = NULL_IF_CONFIG_SMALL("Apple CAF (Core Audio Format)"),

425 .priv_data_size = sizeof(CafContext),

426 .read_probe = probe,

427 .read_header = read_header,

428 .read_packet = read_packet,

429 .read_seek = read_seek,

430 .codec_tag = (const AVCodecTag* const []){ ff_codec_caf_tags, 0 },

431 };

Generated on Sun Mar 8 2015 02:35:09 for FFmpeg by doxygen 1.8.2