MP3Extractor.cpp revision 3e0339f9ec42c2c31deb632254e9cc8a06d3db91
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17//#define LOG_NDEBUG 0 18#define LOG_TAG "MP3Extractor" 19#include <utils/Log.h> 20 21#include "include/MP3Extractor.h" 22 23#include "include/ID3.h" 24 25#include <media/stagefright/DataSource.h> 26#include <media/stagefright/MediaBuffer.h> 27#include <media/stagefright/MediaBufferGroup.h> 28#include <media/stagefright/MediaDebug.h> 29#include <media/stagefright/MediaDefs.h> 30#include <media/stagefright/MediaErrors.h> 31#include <media/stagefright/MediaSource.h> 32#include <media/stagefright/MetaData.h> 33#include <media/stagefright/Utils.h> 34#include <utils/String8.h> 35 36namespace android { 37 38// Everything must match except for 39// protection, bitrate, padding, private bits, mode extension, 40// copyright bit, original bit and emphasis. 41// Yes ... there are things that must indeed match... 42static const uint32_t kMask = 0xfffe0cc0; 43 44static bool get_mp3_frame_size( 45 uint32_t header, size_t *frame_size, 46 int *out_sampling_rate = NULL, int *out_channels = NULL, 47 int *out_bitrate = NULL) { 48 *frame_size = 0; 49 50 if (out_sampling_rate) { 51 *out_sampling_rate = 0; 52 } 53 54 if (out_channels) { 55 *out_channels = 0; 56 } 57 58 if (out_bitrate) { 59 *out_bitrate = 0; 60 } 61 62 if ((header & 0xffe00000) != 0xffe00000) { 63 return false; 64 } 65 66 unsigned version = (header >> 19) & 3; 67 68 if (version == 0x01) { 69 return false; 70 } 71 72 unsigned layer = (header >> 17) & 3; 73 74 if (layer == 0x00) { 75 return false; 76 } 77 78 unsigned protection = (header >> 16) & 1; 79 80 unsigned bitrate_index = (header >> 12) & 0x0f; 81 82 if (bitrate_index == 0 || bitrate_index == 0x0f) { 83 // Disallow "free" bitrate. 84 return false; 85 } 86 87 unsigned sampling_rate_index = (header >> 10) & 3; 88 89 if (sampling_rate_index == 3) { 90 return false; 91 } 92 93 static const int kSamplingRateV1[] = { 44100, 48000, 32000 }; 94 int sampling_rate = kSamplingRateV1[sampling_rate_index]; 95 if (version == 2 /* V2 */) { 96 sampling_rate /= 2; 97 } else if (version == 0 /* V2.5 */) { 98 sampling_rate /= 4; 99 } 100 101 unsigned padding = (header >> 9) & 1; 102 103 if (layer == 3) { 104 // layer I 105 106 static const int kBitrateV1[] = { 107 32, 64, 96, 128, 160, 192, 224, 256, 108 288, 320, 352, 384, 416, 448 109 }; 110 111 static const int kBitrateV2[] = { 112 32, 48, 56, 64, 80, 96, 112, 128, 113 144, 160, 176, 192, 224, 256 114 }; 115 116 int bitrate = 117 (version == 3 /* V1 */) 118 ? kBitrateV1[bitrate_index - 1] 119 : kBitrateV2[bitrate_index - 1]; 120 121 if (out_bitrate) { 122 *out_bitrate = bitrate; 123 } 124 125 *frame_size = (12000 * bitrate / sampling_rate + padding) * 4; 126 } else { 127 // layer II or III 128 129 static const int kBitrateV1L2[] = { 130 32, 48, 56, 64, 80, 96, 112, 128, 131 160, 192, 224, 256, 320, 384 132 }; 133 134 static const int kBitrateV1L3[] = { 135 32, 40, 48, 56, 64, 80, 96, 112, 136 128, 160, 192, 224, 256, 320 137 }; 138 139 static const int kBitrateV2[] = { 140 8, 16, 24, 32, 40, 48, 56, 64, 141 80, 96, 112, 128, 144, 160 142 }; 143 144 int bitrate; 145 if (version == 3 /* V1 */) { 146 bitrate = (layer == 2 /* L2 */) 147 ? kBitrateV1L2[bitrate_index - 1] 148 : kBitrateV1L3[bitrate_index - 1]; 149 } else { 150 // V2 (or 2.5) 151 152 bitrate = kBitrateV2[bitrate_index - 1]; 153 } 154 155 if (out_bitrate) { 156 *out_bitrate = bitrate; 157 } 158 159 if (version == 3 /* V1 */) { 160 *frame_size = 144000 * bitrate / sampling_rate + padding; 161 } else { 162 // V2 or V2.5 163 *frame_size = 72000 * bitrate / sampling_rate + padding; 164 } 165 } 166 167 if (out_sampling_rate) { 168 *out_sampling_rate = sampling_rate; 169 } 170 171 if (out_channels) { 172 int channel_mode = (header >> 6) & 3; 173 174 *out_channels = (channel_mode == 3) ? 1 : 2; 175 } 176 177 return true; 178} 179 180static bool parse_xing_header( 181 const sp<DataSource> &source, off_t first_frame_pos, 182 int32_t *frame_number = NULL, int32_t *byte_number = NULL, 183 char *table_of_contents = NULL, int32_t *quality_indicator = NULL, 184 int64_t *duration = NULL) { 185 186 if (frame_number) { 187 *frame_number = 0; 188 } 189 if (byte_number) { 190 *byte_number = 0; 191 } 192 if (table_of_contents) { 193 table_of_contents[0] = 0; 194 } 195 if (quality_indicator) { 196 *quality_indicator = 0; 197 } 198 if (duration) { 199 *duration = 0; 200 } 201 202 uint8_t buffer[4]; 203 int offset = first_frame_pos; 204 if (source->readAt(offset, &buffer, 4) < 4) { // get header 205 return false; 206 } 207 offset += 4; 208 209 uint8_t id, layer, sr_index, mode; 210 layer = (buffer[1] >> 1) & 3; 211 id = (buffer[1] >> 3) & 3; 212 sr_index = (buffer[2] >> 2) & 3; 213 mode = (buffer[3] >> 6) & 3; 214 if (layer == 0) { 215 return false; 216 } 217 if (id == 1) { 218 return false; 219 } 220 if (sr_index == 3) { 221 return false; 222 } 223 // determine offset of XING header 224 if(id&1) { // mpeg1 225 if (mode != 3) offset += 32; 226 else offset += 17; 227 } else { // mpeg2 228 if (mode != 3) offset += 17; 229 else offset += 9; 230 } 231 232 if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID 233 return false; 234 } 235 offset += 4; 236 // Check XING ID 237 if ((buffer[0] != 'X') || (buffer[1] != 'i') 238 || (buffer[2] != 'n') || (buffer[3] != 'g')) { 239 if ((buffer[0] != 'I') || (buffer[1] != 'n') 240 || (buffer[2] != 'f') || (buffer[3] != 'o')) { 241 return false; 242 } 243 } 244 245 if (source->readAt(offset, &buffer, 4) < 4) { // flags 246 return false; 247 } 248 offset += 4; 249 uint32_t flags = U32_AT(buffer); 250 251 if (flags & 0x0001) { // Frames field is present 252 if (source->readAt(offset, buffer, 4) < 4) { 253 return false; 254 } 255 if (frame_number) { 256 *frame_number = U32_AT(buffer); 257 } 258 int32_t frame = U32_AT(buffer); 259 // Samples per Frame: 1. index = MPEG Version ID, 2. index = Layer 260 const int samplesPerFrames[2][3] = 261 { 262 { 384, 1152, 576 }, // MPEG 2, 2.5: layer1, layer2, layer3 263 { 384, 1152, 1152 }, // MPEG 1: layer1, layer2, layer3 264 }; 265 // sampling rates in hertz: 1. index = MPEG Version ID, 2. index = sampling rate index 266 const int samplingRates[4][3] = 267 { 268 { 11025, 12000, 8000, }, // MPEG 2.5 269 { 0, 0, 0, }, // reserved 270 { 22050, 24000, 16000, }, // MPEG 2 271 { 44100, 48000, 32000, } // MPEG 1 272 }; 273 if (duration) { 274 *duration = (int64_t)frame * samplesPerFrames[id&1][3-layer] * 1000000LL 275 / samplingRates[id][sr_index]; 276 } 277 offset += 4; 278 } 279 if (flags & 0x0002) { // Bytes field is present 280 if (byte_number) { 281 if (source->readAt(offset, buffer, 4) < 4) { 282 return false; 283 } 284 *byte_number = U32_AT(buffer); 285 } 286 offset += 4; 287 } 288 if (flags & 0x0004) { // TOC field is present 289 if (table_of_contents) { 290 if (source->readAt(offset + 1, table_of_contents, 99) < 99) { 291 return false; 292 } 293 } 294 offset += 100; 295 } 296 if (flags & 0x0008) { // Quality indicator field is present 297 if (quality_indicator) { 298 if (source->readAt(offset, buffer, 4) < 4) { 299 return false; 300 } 301 *quality_indicator = U32_AT(buffer); 302 } 303 } 304 return true; 305} 306 307static bool Resync( 308 const sp<DataSource> &source, uint32_t match_header, 309 off_t *inout_pos, uint32_t *out_header) { 310 if (*inout_pos == 0) { 311 // Skip an optional ID3 header if syncing at the very beginning 312 // of the datasource. 313 314 for (;;) { 315 uint8_t id3header[10]; 316 if (source->readAt(*inout_pos, id3header, sizeof(id3header)) 317 < (ssize_t)sizeof(id3header)) { 318 // If we can't even read these 10 bytes, we might as well bail 319 // out, even if there _were_ 10 bytes of valid mp3 audio data... 320 return false; 321 } 322 323 if (memcmp("ID3", id3header, 3)) { 324 break; 325 } 326 327 // Skip the ID3v2 header. 328 329 size_t len = 330 ((id3header[6] & 0x7f) << 21) 331 | ((id3header[7] & 0x7f) << 14) 332 | ((id3header[8] & 0x7f) << 7) 333 | (id3header[9] & 0x7f); 334 335 len += 10; 336 337 *inout_pos += len; 338 339 LOGV("skipped ID3 tag, new starting offset is %ld (0x%08lx)", 340 *inout_pos, *inout_pos); 341 } 342 } 343 344 off_t pos = *inout_pos; 345 bool valid = false; 346 do { 347 if (pos >= *inout_pos + 128 * 1024) { 348 // Don't scan forever. 349 LOGV("giving up at offset %ld", pos); 350 break; 351 } 352 353 uint8_t tmp[4]; 354 if (source->readAt(pos, tmp, 4) != 4) { 355 break; 356 } 357 358 uint32_t header = U32_AT(tmp); 359 360 if (match_header != 0 && (header & kMask) != (match_header & kMask)) { 361 ++pos; 362 continue; 363 } 364 365 size_t frame_size; 366 int sample_rate, num_channels, bitrate; 367 if (!get_mp3_frame_size(header, &frame_size, 368 &sample_rate, &num_channels, &bitrate)) { 369 ++pos; 370 continue; 371 } 372 373 LOGV("found possible 1st frame at %ld (header = 0x%08x)", pos, header); 374 375 // We found what looks like a valid frame, 376 // now find its successors. 377 378 off_t test_pos = pos + frame_size; 379 380 valid = true; 381 for (int j = 0; j < 3; ++j) { 382 uint8_t tmp[4]; 383 if (source->readAt(test_pos, tmp, 4) < 4) { 384 valid = false; 385 break; 386 } 387 388 uint32_t test_header = U32_AT(tmp); 389 390 LOGV("subsequent header is %08x", test_header); 391 392 if ((test_header & kMask) != (header & kMask)) { 393 valid = false; 394 break; 395 } 396 397 size_t test_frame_size; 398 if (!get_mp3_frame_size(test_header, &test_frame_size)) { 399 valid = false; 400 break; 401 } 402 403 LOGV("found subsequent frame #%d at %ld", j + 2, test_pos); 404 405 test_pos += test_frame_size; 406 } 407 408 if (valid) { 409 *inout_pos = pos; 410 411 if (out_header != NULL) { 412 *out_header = header; 413 } 414 } else { 415 LOGV("no dice, no valid sequence of frames found."); 416 } 417 418 ++pos; 419 } while (!valid); 420 421 return valid; 422} 423 424class MP3Source : public MediaSource { 425public: 426 MP3Source( 427 const sp<MetaData> &meta, const sp<DataSource> &source, 428 off_t first_frame_pos, uint32_t fixed_header, 429 int32_t byte_number, const char *table_of_contents); 430 431 virtual status_t start(MetaData *params = NULL); 432 virtual status_t stop(); 433 434 virtual sp<MetaData> getFormat(); 435 436 virtual status_t read( 437 MediaBuffer **buffer, const ReadOptions *options = NULL); 438 439protected: 440 virtual ~MP3Source(); 441 442private: 443 sp<MetaData> mMeta; 444 sp<DataSource> mDataSource; 445 off_t mFirstFramePos; 446 uint32_t mFixedHeader; 447 off_t mCurrentPos; 448 int64_t mCurrentTimeUs; 449 bool mStarted; 450 int32_t mByteNumber; // total number of bytes in this MP3 451 // TOC entries in XING header. Skip the first one since it's always 0. 452 char mTableOfContents[99]; 453 MediaBufferGroup *mGroup; 454 455 MP3Source(const MP3Source &); 456 MP3Source &operator=(const MP3Source &); 457}; 458 459MP3Extractor::MP3Extractor(const sp<DataSource> &source) 460 : mDataSource(source), 461 mFirstFramePos(-1), 462 mFixedHeader(0), 463 mByteNumber(0) { 464 off_t pos = 0; 465 uint32_t header; 466 bool success = Resync(mDataSource, 0, &pos, &header); 467 CHECK(success); 468 469 if (success) { 470 mFirstFramePos = pos; 471 mFixedHeader = header; 472 473 size_t frame_size; 474 int sample_rate; 475 int num_channels; 476 int bitrate; 477 get_mp3_frame_size( 478 header, &frame_size, &sample_rate, &num_channels, &bitrate); 479 480 mMeta = new MetaData; 481 482 mMeta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_MPEG); 483 mMeta->setInt32(kKeySampleRate, sample_rate); 484 mMeta->setInt32(kKeyBitRate, bitrate * 1000); 485 mMeta->setInt32(kKeyChannelCount, num_channels); 486 487 int64_t duration; 488 parse_xing_header( 489 mDataSource, mFirstFramePos, NULL, &mByteNumber, 490 mTableOfContents, NULL, &duration); 491 if (duration > 0) { 492 mMeta->setInt64(kKeyDuration, duration); 493 } else { 494 off_t fileSize; 495 if (mDataSource->getSize(&fileSize) == OK) { 496 mMeta->setInt64( 497 kKeyDuration, 498 8000LL * (fileSize - mFirstFramePos) / bitrate); 499 } 500 } 501 } 502} 503 504MP3Extractor::~MP3Extractor() { 505} 506 507size_t MP3Extractor::countTracks() { 508 return (mFirstFramePos < 0) ? 0 : 1; 509} 510 511sp<MediaSource> MP3Extractor::getTrack(size_t index) { 512 if (mFirstFramePos < 0 || index != 0) { 513 return NULL; 514 } 515 516 return new MP3Source( 517 mMeta, mDataSource, mFirstFramePos, mFixedHeader, 518 mByteNumber, mTableOfContents); 519} 520 521sp<MetaData> MP3Extractor::getTrackMetaData(size_t index, uint32_t flags) { 522 if (mFirstFramePos < 0 || index != 0) { 523 return NULL; 524 } 525 526 return mMeta; 527} 528 529//////////////////////////////////////////////////////////////////////////////// 530 531MP3Source::MP3Source( 532 const sp<MetaData> &meta, const sp<DataSource> &source, 533 off_t first_frame_pos, uint32_t fixed_header, 534 int32_t byte_number, const char *table_of_contents) 535 : mMeta(meta), 536 mDataSource(source), 537 mFirstFramePos(first_frame_pos), 538 mFixedHeader(fixed_header), 539 mCurrentPos(0), 540 mCurrentTimeUs(0), 541 mStarted(false), 542 mByteNumber(byte_number), 543 mGroup(NULL) { 544 memcpy (mTableOfContents, table_of_contents, sizeof(mTableOfContents)); 545} 546 547MP3Source::~MP3Source() { 548 if (mStarted) { 549 stop(); 550 } 551} 552 553status_t MP3Source::start(MetaData *) { 554 CHECK(!mStarted); 555 556 mGroup = new MediaBufferGroup; 557 558 const size_t kMaxFrameSize = 32768; 559 mGroup->add_buffer(new MediaBuffer(kMaxFrameSize)); 560 561 mCurrentPos = mFirstFramePos; 562 mCurrentTimeUs = 0; 563 564 mStarted = true; 565 566 return OK; 567} 568 569status_t MP3Source::stop() { 570 CHECK(mStarted); 571 572 delete mGroup; 573 mGroup = NULL; 574 575 mStarted = false; 576 577 return OK; 578} 579 580sp<MetaData> MP3Source::getFormat() { 581 return mMeta; 582} 583 584status_t MP3Source::read( 585 MediaBuffer **out, const ReadOptions *options) { 586 *out = NULL; 587 588 int64_t seekTimeUs; 589 if (options != NULL && options->getSeekTo(&seekTimeUs)) { 590 int32_t bitrate; 591 if (!mMeta->findInt32(kKeyBitRate, &bitrate)) { 592 // bitrate is in bits/sec. 593 LOGI("no bitrate"); 594 595 return ERROR_UNSUPPORTED; 596 } 597 598 mCurrentTimeUs = seekTimeUs; 599 // interpolate in TOC to get file seek point in bytes 600 int64_t duration; 601 if ((mByteNumber > 0) && (mTableOfContents[0] > 0) 602 && mMeta->findInt64(kKeyDuration, &duration)) { 603 float percent = (float)seekTimeUs * 100 / duration; 604 float fx; 605 if( percent <= 0.0f ) { 606 fx = 0.0f; 607 } else if( percent >= 100.0f ) { 608 fx = 256.0f; 609 } else { 610 int a = (int)percent; 611 float fa, fb; 612 if ( a == 0 ) { 613 fa = 0.0f; 614 } else { 615 fa = (float)mTableOfContents[a-1]; 616 } 617 if ( a < 99 ) { 618 fb = (float)mTableOfContents[a]; 619 } else { 620 fb = 256.0f; 621 } 622 fx = fa + (fb-fa)*(percent-a); 623 } 624 mCurrentPos = mFirstFramePos + (int)((1.0f/256.0f)*fx*mByteNumber); 625 } else { 626 mCurrentPos = mFirstFramePos + seekTimeUs * bitrate / 8000000; 627 } 628 } 629 630 MediaBuffer *buffer; 631 status_t err = mGroup->acquire_buffer(&buffer); 632 if (err != OK) { 633 return err; 634 } 635 636 size_t frame_size; 637 int bitrate; 638 for (;;) { 639 ssize_t n = mDataSource->readAt(mCurrentPos, buffer->data(), 4); 640 if (n < 4) { 641 buffer->release(); 642 buffer = NULL; 643 644 return ERROR_END_OF_STREAM; 645 } 646 647 uint32_t header = U32_AT((const uint8_t *)buffer->data()); 648 649 if ((header & kMask) == (mFixedHeader & kMask) 650 && get_mp3_frame_size(header, &frame_size, NULL, NULL, &bitrate)) { 651 break; 652 } 653 654 // Lost sync. 655 LOGV("lost sync! header = 0x%08x, old header = 0x%08x\n", header, mFixedHeader); 656 657 off_t pos = mCurrentPos; 658 if (!Resync(mDataSource, mFixedHeader, &pos, NULL)) { 659 LOGE("Unable to resync. Signalling end of stream."); 660 661 buffer->release(); 662 buffer = NULL; 663 664 return ERROR_END_OF_STREAM; 665 } 666 667 mCurrentPos = pos; 668 669 // Try again with the new position. 670 } 671 672 CHECK(frame_size <= buffer->size()); 673 674 ssize_t n = mDataSource->readAt(mCurrentPos, buffer->data(), frame_size); 675 if (n < (ssize_t)frame_size) { 676 buffer->release(); 677 buffer = NULL; 678 679 return ERROR_END_OF_STREAM; 680 } 681 682 buffer->set_range(0, frame_size); 683 684 buffer->meta_data()->setInt64(kKeyTime, mCurrentTimeUs); 685 686 mCurrentPos += frame_size; 687 mCurrentTimeUs += frame_size * 8000ll / bitrate; 688 689 *out = buffer; 690 691 return OK; 692} 693 694sp<MetaData> MP3Extractor::getMetaData() { 695 sp<MetaData> meta = new MetaData; 696 697 if (mFirstFramePos < 0) { 698 return meta; 699 } 700 701 meta->setCString(kKeyMIMEType, "audio/mpeg"); 702 703 ID3 id3(mDataSource); 704 705 if (!id3.isValid()) { 706 return meta; 707 } 708 709 struct Map { 710 int key; 711 const char *tag1; 712 const char *tag2; 713 }; 714 static const Map kMap[] = { 715 { kKeyAlbum, "TALB", "TAL" }, 716 { kKeyArtist, "TPE1", "TP1" }, 717 { kKeyAlbumArtist, "TPE2", "TP2" }, 718 { kKeyComposer, "TCOM", "TCM" }, 719 { kKeyGenre, "TCON", "TCO" }, 720 { kKeyTitle, "TIT2", "TT2" }, 721 { kKeyYear, "TYE", "TYER" }, 722 { kKeyAuthor, "TXT", "TEXT" }, 723 { kKeyCDTrackNumber, "TRK", "TRCK" }, 724 { kKeyDiscNumber, "TPA", "TPOS" }, 725 }; 726 static const size_t kNumMapEntries = sizeof(kMap) / sizeof(kMap[0]); 727 728 for (size_t i = 0; i < kNumMapEntries; ++i) { 729 ID3::Iterator *it = new ID3::Iterator(id3, kMap[i].tag1); 730 if (it->done()) { 731 delete it; 732 it = new ID3::Iterator(id3, kMap[i].tag2); 733 } 734 735 if (it->done()) { 736 delete it; 737 continue; 738 } 739 740 String8 s; 741 it->getString(&s); 742 delete it; 743 744 meta->setCString(kMap[i].key, s); 745 } 746 747 size_t dataSize; 748 String8 mime; 749 const void *data = id3.getAlbumArt(&dataSize, &mime); 750 751 if (data) { 752 meta->setData(kKeyAlbumArt, MetaData::TYPE_NONE, data, dataSize); 753 meta->setCString(kKeyAlbumArtMIME, mime.string()); 754 } 755 756 return meta; 757} 758 759bool SniffMP3( 760 const sp<DataSource> &source, String8 *mimeType, float *confidence) { 761 off_t pos = 0; 762 uint32_t header; 763 if (!Resync(source, 0, &pos, &header)) { 764 return false; 765 } 766 767 *mimeType = MEDIA_MIMETYPE_AUDIO_MPEG; 768 *confidence = 0.3f; 769 770 return true; 771} 772 773} // namespace android 774