ID3.cpp revision f6d0c1fd6d9e697bb3a891fae14c7e9d4b685de6 
1/*
2 * Copyright (C) 2010 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 "ID3"
19#include <utils/Log.h>
20
21#include "../include/ID3.h"
22
23#include <media/stagefright/foundation/ADebug.h>
24#include <media/stagefright/DataSource.h>
25#include <media/stagefright/Utils.h>
26#include <utils/String8.h>
27#include <byteswap.h>
28
29namespace android {
30
31static const size_t kMaxMetadataSize = 3 * 1024 * 1024;
32
33struct MemorySource : public DataSource {
34    MemorySource(const uint8_t *data, size_t size)
35        : mData(data),
36          mSize(size) {
37    }
38
39    virtual status_t initCheck() const {
40        return OK;
41    }
42
43    virtual ssize_t readAt(off64_t offset, void *data, size_t size) {
44        off64_t available = (offset >= (off64_t)mSize) ? 0ll : mSize - offset;
45
46        size_t copy = (available > (off64_t)size) ? size : available;
47        memcpy(data, mData + offset, copy);
48
49        return copy;
50    }
51
52private:
53    const uint8_t *mData;
54    size_t mSize;
55
56    DISALLOW_EVIL_CONSTRUCTORS(MemorySource);
57};
58
59ID3::ID3(const sp<DataSource> &source, bool ignoreV1, off64_t offset)
60    : mIsValid(false),
61      mData(NULL),
62      mSize(0),
63      mFirstFrameOffset(0),
64      mVersion(ID3_UNKNOWN),
65      mRawSize(0) {
66    mIsValid = parseV2(source, offset);
67
68    if (!mIsValid && !ignoreV1) {
69        mIsValid = parseV1(source);
70    }
71}
72
73ID3::ID3(const uint8_t *data, size_t size, bool ignoreV1)
74    : mIsValid(false),
75      mData(NULL),
76      mSize(0),
77      mFirstFrameOffset(0),
78      mVersion(ID3_UNKNOWN),
79      mRawSize(0) {
80    sp<MemorySource> source = new MemorySource(data, size);
81
82    mIsValid = parseV2(source, 0);
83
84    if (!mIsValid && !ignoreV1) {
85        mIsValid = parseV1(source);
86    }
87}
88
89ID3::~ID3() {
90    if (mData) {
91        free(mData);
92        mData = NULL;
93    }
94}
95
96bool ID3::isValid() const {
97    return mIsValid;
98}
99
100ID3::Version ID3::version() const {
101    return mVersion;
102}
103
104// static
105bool ID3::ParseSyncsafeInteger(const uint8_t encoded[4], size_t *x) {
106    *x = 0;
107    for (int32_t i = 0; i < 4; ++i) {
108        if (encoded[i] & 0x80) {
109            return false;
110        }
111
112        *x = ((*x) << 7) | encoded[i];
113    }
114
115    return true;
116}
117
118bool ID3::parseV2(const sp<DataSource> &source, off64_t offset) {
119struct id3_header {
120    char id[3];
121    uint8_t version_major;
122    uint8_t version_minor;
123    uint8_t flags;
124    uint8_t enc_size[4];
125    };
126
127    id3_header header;
128    if (source->readAt(
129                offset, &header, sizeof(header)) != (ssize_t)sizeof(header)) {
130        return false;
131    }
132
133    if (memcmp(header.id, "ID3", 3)) {
134        return false;
135    }
136
137    if (header.version_major == 0xff || header.version_minor == 0xff) {
138        return false;
139    }
140
141    if (header.version_major == 2) {
142        if (header.flags & 0x3f) {
143            // We only support the 2 high bits, if any of the lower bits are
144            // set, we cannot guarantee to understand the tag format.
145            return false;
146        }
147
148        if (header.flags & 0x40) {
149            // No compression scheme has been decided yet, ignore the
150            // tag if compression is indicated.
151
152            return false;
153        }
154    } else if (header.version_major == 3) {
155        if (header.flags & 0x1f) {
156            // We only support the 3 high bits, if any of the lower bits are
157            // set, we cannot guarantee to understand the tag format.
158            return false;
159        }
160    } else if (header.version_major == 4) {
161        if (header.flags & 0x0f) {
162            // The lower 4 bits are undefined in this spec.
163            return false;
164        }
165    } else {
166        return false;
167    }
168
169    size_t size;
170    if (!ParseSyncsafeInteger(header.enc_size, &size)) {
171        return false;
172    }
173
174    if (size > kMaxMetadataSize) {
175        ALOGE("skipping huge ID3 metadata of size %zu", size);
176        return false;
177    }
178
179    mData = (uint8_t *)malloc(size);
180
181    if (mData == NULL) {
182        return false;
183    }
184
185    mSize = size;
186    mRawSize = mSize + sizeof(header);
187
188    if (source->readAt(offset + sizeof(header), mData, mSize) != (ssize_t)mSize) {
189        free(mData);
190        mData = NULL;
191
192        return false;
193    }
194
195    if (header.version_major == 4) {
196        void *copy = malloc(size);
197        memcpy(copy, mData, size);
198
199        bool success = removeUnsynchronizationV2_4(false /* iTunesHack */);
200        if (!success) {
201            memcpy(mData, copy, size);
202            mSize = size;
203
204            success = removeUnsynchronizationV2_4(true /* iTunesHack */);
205
206            if (success) {
207                ALOGV("Had to apply the iTunes hack to parse this ID3 tag");
208            }
209        }
210
211        free(copy);
212        copy = NULL;
213
214        if (!success) {
215            free(mData);
216            mData = NULL;
217
218            return false;
219        }
220    } else if (header.flags & 0x80) {
221        ALOGV("removing unsynchronization");
222
223        removeUnsynchronization();
224    }
225
226    mFirstFrameOffset = 0;
227    if (header.version_major == 3 && (header.flags & 0x40)) {
228        // Version 2.3 has an optional extended header.
229
230        if (mSize < 4) {
231            free(mData);
232            mData = NULL;
233
234            return false;
235        }
236
237        size_t extendedHeaderSize = U32_AT(&mData[0]) + 4;
238
239        if (extendedHeaderSize > mSize) {
240            free(mData);
241            mData = NULL;
242
243            return false;
244        }
245
246        mFirstFrameOffset = extendedHeaderSize;
247
248        uint16_t extendedFlags = 0;
249        if (extendedHeaderSize >= 6) {
250            extendedFlags = U16_AT(&mData[4]);
251
252            if (extendedHeaderSize >= 10) {
253                size_t paddingSize = U32_AT(&mData[6]);
254
255                if (mFirstFrameOffset + paddingSize > mSize) {
256                    free(mData);
257                    mData = NULL;
258
259                    return false;
260                }
261
262                mSize -= paddingSize;
263            }
264
265            if (extendedFlags & 0x8000) {
266                ALOGV("have crc");
267            }
268        }
269    } else if (header.version_major == 4 && (header.flags & 0x40)) {
270        // Version 2.4 has an optional extended header, that's different
271        // from Version 2.3's...
272
273        if (mSize < 4) {
274            free(mData);
275            mData = NULL;
276
277            return false;
278        }
279
280        size_t ext_size;
281        if (!ParseSyncsafeInteger(mData, &ext_size)) {
282            free(mData);
283            mData = NULL;
284
285            return false;
286        }
287
288        if (ext_size < 6 || ext_size > mSize) {
289            free(mData);
290            mData = NULL;
291
292            return false;
293        }
294
295        mFirstFrameOffset = ext_size;
296    }
297
298    if (header.version_major == 2) {
299        mVersion = ID3_V2_2;
300    } else if (header.version_major == 3) {
301        mVersion = ID3_V2_3;
302    } else {
303        CHECK_EQ(header.version_major, 4);
304        mVersion = ID3_V2_4;
305    }
306
307    return true;
308}
309
310void ID3::removeUnsynchronization() {
311    for (size_t i = 0; i + 1 < mSize; ++i) {
312        if (mData[i] == 0xff && mData[i + 1] == 0x00) {
313            memmove(&mData[i + 1], &mData[i + 2], mSize - i - 2);
314            --mSize;
315        }
316    }
317}
318
319static void WriteSyncsafeInteger(uint8_t *dst, size_t x) {
320    for (size_t i = 0; i < 4; ++i) {
321        dst[3 - i] = (x & 0x7f);
322        x >>= 7;
323    }
324}
325
326bool ID3::removeUnsynchronizationV2_4(bool iTunesHack) {
327    size_t oldSize = mSize;
328
329    size_t offset = 0;
330    while (offset + 10 <= mSize) {
331        if (!memcmp(&mData[offset], "\0\0\0\0", 4)) {
332            break;
333        }
334
335        size_t dataSize;
336        if (iTunesHack) {
337            dataSize = U32_AT(&mData[offset + 4]);
338        } else if (!ParseSyncsafeInteger(&mData[offset + 4], &dataSize)) {
339            return false;
340        }
341
342        if (offset + dataSize + 10 > mSize) {
343            return false;
344        }
345
346        uint16_t flags = U16_AT(&mData[offset + 8]);
347        uint16_t prevFlags = flags;
348
349        if (flags & 1) {
350            // Strip data length indicator
351
352            memmove(&mData[offset + 10], &mData[offset + 14], mSize - offset - 14);
353            mSize -= 4;
354            dataSize -= 4;
355
356            flags &= ~1;
357        }
358
359        if (flags & 2) {
360            // This file has "unsynchronization", so we have to replace occurrences
361            // of 0xff 0x00 with just 0xff in order to get the real data.
362
363            size_t readOffset = offset + 11;
364            size_t writeOffset = offset + 11;
365            for (size_t i = 0; i + 1 < dataSize; ++i) {
366                if (mData[readOffset - 1] == 0xff
367                        && mData[readOffset] == 0x00) {
368                    ++readOffset;
369                    --mSize;
370                    --dataSize;
371                }
372                mData[writeOffset++] = mData[readOffset++];
373            }
374            // move the remaining data following this frame
375            memmove(&mData[writeOffset], &mData[readOffset], oldSize - readOffset);
376
377            flags &= ~2;
378        }
379
380        if (flags != prevFlags || iTunesHack) {
381            WriteSyncsafeInteger(&mData[offset + 4], dataSize);
382            mData[offset + 8] = flags >> 8;
383            mData[offset + 9] = flags & 0xff;
384        }
385
386        offset += 10 + dataSize;
387    }
388
389    memset(&mData[mSize], 0, oldSize - mSize);
390
391    return true;
392}
393
394ID3::Iterator::Iterator(const ID3 &parent, const char *id)
395    : mParent(parent),
396      mID(NULL),
397      mOffset(mParent.mFirstFrameOffset),
398      mFrameData(NULL),
399      mFrameSize(0) {
400    if (id) {
401        mID = strdup(id);
402    }
403
404    findFrame();
405}
406
407ID3::Iterator::~Iterator() {
408    if (mID) {
409        free(mID);
410        mID = NULL;
411    }
412}
413
414bool ID3::Iterator::done() const {
415    return mFrameData == NULL;
416}
417
418void ID3::Iterator::next() {
419    if (mFrameData == NULL) {
420        return;
421    }
422
423    mOffset += mFrameSize;
424
425    findFrame();
426}
427
428void ID3::Iterator::getID(String8 *id) const {
429    id->setTo("");
430
431    if (mFrameData == NULL) {
432        return;
433    }
434
435    if (mParent.mVersion == ID3_V2_2) {
436        id->setTo((const char *)&mParent.mData[mOffset], 3);
437    } else if (mParent.mVersion == ID3_V2_3 || mParent.mVersion == ID3_V2_4) {
438        id->setTo((const char *)&mParent.mData[mOffset], 4);
439    } else {
440        CHECK(mParent.mVersion == ID3_V1 || mParent.mVersion == ID3_V1_1);
441
442        switch (mOffset) {
443            case 3:
444                id->setTo("TT2");
445                break;
446            case 33:
447                id->setTo("TP1");
448                break;
449            case 63:
450                id->setTo("TAL");
451                break;
452            case 93:
453                id->setTo("TYE");
454                break;
455            case 97:
456                id->setTo("COM");
457                break;
458            case 126:
459                id->setTo("TRK");
460                break;
461            case 127:
462                id->setTo("TCO");
463                break;
464            default:
465                CHECK(!"should not be here.");
466                break;
467        }
468    }
469}
470
471static void convertISO8859ToString8(
472        const uint8_t *data, size_t size,
473        String8 *s) {
474    size_t utf8len = 0;
475    for (size_t i = 0; i < size; ++i) {
476        if (data[i] == '\0') {
477            size = i;
478            break;
479        } else if (data[i] < 0x80) {
480            ++utf8len;
481        } else {
482            utf8len += 2;
483        }
484    }
485
486    if (utf8len == size) {
487        // Only ASCII characters present.
488
489        s->setTo((const char *)data, size);
490        return;
491    }
492
493    char *tmp = new char[utf8len];
494    char *ptr = tmp;
495    for (size_t i = 0; i < size; ++i) {
496        if (data[i] == '\0') {
497            break;
498        } else if (data[i] < 0x80) {
499            *ptr++ = data[i];
500        } else if (data[i] < 0xc0) {
501            *ptr++ = 0xc2;
502            *ptr++ = data[i];
503        } else {
504            *ptr++ = 0xc3;
505            *ptr++ = data[i] - 64;
506        }
507    }
508
509    s->setTo(tmp, utf8len);
510
511    delete[] tmp;
512    tmp = NULL;
513}
514
515// the 2nd argument is used to get the data following the \0 in a comment field
516void ID3::Iterator::getString(String8 *id, String8 *comment) const {
517    getstring(id, false);
518    if (comment != NULL) {
519        getstring(comment, true);
520    }
521}
522
523// comment fields (COM/COMM) contain an initial short descriptor, followed by \0,
524// followed by more data. The data following the \0 can be retrieved by setting
525// "otherdata" to true.
526void ID3::Iterator::getstring(String8 *id, bool otherdata) const {
527    id->setTo("");
528
529    const uint8_t *frameData = mFrameData;
530    if (frameData == NULL) {
531        return;
532    }
533
534    uint8_t encoding = *frameData;
535
536    if (mParent.mVersion == ID3_V1 || mParent.mVersion == ID3_V1_1) {
537        if (mOffset == 126 || mOffset == 127) {
538            // Special treatment for the track number and genre.
539            char tmp[16];
540            sprintf(tmp, "%d", (int)*frameData);
541
542            id->setTo(tmp);
543            return;
544        }
545
546        convertISO8859ToString8(frameData, mFrameSize, id);
547        return;
548    }
549
550    size_t n = mFrameSize - getHeaderLength() - 1;
551    if (otherdata) {
552        // skip past the encoding, language, and the 0 separator
553        frameData += 4;
554        int32_t i = n - 4;
555        while(--i >= 0 && *++frameData != 0) ;
556        int skipped = (frameData - mFrameData);
557        if (skipped >= (int)n) {
558            return;
559        }
560        n -= skipped;
561    }
562
563    if (encoding == 0x00) {
564        // ISO 8859-1
565        convertISO8859ToString8(frameData + 1, n, id);
566    } else if (encoding == 0x03) {
567        // UTF-8
568        id->setTo((const char *)(frameData + 1), n);
569    } else if (encoding == 0x02) {
570        // UTF-16 BE, no byte order mark.
571        // API wants number of characters, not number of bytes...
572        int len = n / 2;
573        const char16_t *framedata = (const char16_t *) (frameData + 1);
574        char16_t *framedatacopy = NULL;
575#if BYTE_ORDER == LITTLE_ENDIAN
576        framedatacopy = new char16_t[len];
577        for (int i = 0; i < len; i++) {
578            framedatacopy[i] = bswap_16(framedata[i]);
579        }
580        framedata = framedatacopy;
581#endif
582        id->setTo(framedata, len);
583        if (framedatacopy != NULL) {
584            delete[] framedatacopy;
585        }
586    } else {
587        // UCS-2
588        // API wants number of characters, not number of bytes...
589        int len = n / 2;
590        const char16_t *framedata = (const char16_t *) (frameData + 1);
591        char16_t *framedatacopy = NULL;
592        if (*framedata == 0xfffe) {
593            // endianness marker doesn't match host endianness, convert
594            framedatacopy = new char16_t[len];
595            for (int i = 0; i < len; i++) {
596                framedatacopy[i] = bswap_16(framedata[i]);
597            }
598            framedata = framedatacopy;
599        }
600        // If the string starts with an endianness marker, skip it
601        if (*framedata == 0xfeff) {
602            framedata++;
603            len--;
604        }
605        id->setTo(framedata, len);
606        if (framedatacopy != NULL) {
607            delete[] framedatacopy;
608        }
609    }
610}
611
612const uint8_t *ID3::Iterator::getData(size_t *length) const {
613    *length = 0;
614
615    if (mFrameData == NULL) {
616        return NULL;
617    }
618
619    *length = mFrameSize - getHeaderLength();
620
621    return mFrameData;
622}
623
624size_t ID3::Iterator::getHeaderLength() const {
625    if (mParent.mVersion == ID3_V2_2) {
626        return 6;
627    } else if (mParent.mVersion == ID3_V2_3 || mParent.mVersion == ID3_V2_4) {
628        return 10;
629    } else {
630        CHECK(mParent.mVersion == ID3_V1 || mParent.mVersion == ID3_V1_1);
631        return 0;
632    }
633}
634
635void ID3::Iterator::findFrame() {
636    for (;;) {
637        mFrameData = NULL;
638        mFrameSize = 0;
639
640        if (mParent.mVersion == ID3_V2_2) {
641            if (mOffset + 6 > mParent.mSize) {
642                return;
643            }
644
645            if (!memcmp(&mParent.mData[mOffset], "\0\0\0", 3)) {
646                return;
647            }
648
649            mFrameSize =
650                (mParent.mData[mOffset + 3] << 16)
651                | (mParent.mData[mOffset + 4] << 8)
652                | mParent.mData[mOffset + 5];
653
654            mFrameSize += 6;
655
656            if (mOffset + mFrameSize > mParent.mSize) {
657                ALOGV("partial frame at offset %zu (size = %zu, bytes-remaining = %zu)",
658                    mOffset, mFrameSize, mParent.mSize - mOffset - (size_t)6);
659                return;
660            }
661
662            mFrameData = &mParent.mData[mOffset + 6];
663
664            if (!mID) {
665                break;
666            }
667
668            char id[4];
669            memcpy(id, &mParent.mData[mOffset], 3);
670            id[3] = '\0';
671
672            if (!strcmp(id, mID)) {
673                break;
674            }
675        } else if (mParent.mVersion == ID3_V2_3
676                || mParent.mVersion == ID3_V2_4) {
677            if (mOffset + 10 > mParent.mSize) {
678                return;
679            }
680
681            if (!memcmp(&mParent.mData[mOffset], "\0\0\0\0", 4)) {
682                return;
683            }
684
685            size_t baseSize;
686            if (mParent.mVersion == ID3_V2_4) {
687                if (!ParseSyncsafeInteger(
688                            &mParent.mData[mOffset + 4], &baseSize)) {
689                    return;
690                }
691            } else {
692                baseSize = U32_AT(&mParent.mData[mOffset + 4]);
693            }
694
695            mFrameSize = 10 + baseSize;
696
697            if (mOffset + mFrameSize > mParent.mSize) {
698                ALOGV("partial frame at offset %zu (size = %zu, bytes-remaining = %zu)",
699                    mOffset, mFrameSize, mParent.mSize - mOffset - (size_t)10);
700                return;
701            }
702
703            uint16_t flags = U16_AT(&mParent.mData[mOffset + 8]);
704
705            if ((mParent.mVersion == ID3_V2_4 && (flags & 0x000c))
706                || (mParent.mVersion == ID3_V2_3 && (flags & 0x00c0))) {
707                // Compression or encryption are not supported at this time.
708                // Per-frame unsynchronization and data-length indicator
709                // have already been taken care of.
710
711                ALOGV("Skipping unsupported frame (compression, encryption "
712                     "or per-frame unsynchronization flagged");
713
714                mOffset += mFrameSize;
715                continue;
716            }
717
718            mFrameData = &mParent.mData[mOffset + 10];
719
720            if (!mID) {
721                break;
722            }
723
724            char id[5];
725            memcpy(id, &mParent.mData[mOffset], 4);
726            id[4] = '\0';
727
728            if (!strcmp(id, mID)) {
729                break;
730            }
731        } else {
732            CHECK(mParent.mVersion == ID3_V1 || mParent.mVersion == ID3_V1_1);
733
734            if (mOffset >= mParent.mSize) {
735                return;
736            }
737
738            mFrameData = &mParent.mData[mOffset];
739
740            switch (mOffset) {
741                case 3:
742                case 33:
743                case 63:
744                    mFrameSize = 30;
745                    break;
746                case 93:
747                    mFrameSize = 4;
748                    break;
749                case 97:
750                    if (mParent.mVersion == ID3_V1) {
751                        mFrameSize = 30;
752                    } else {
753                        mFrameSize = 29;
754                    }
755                    break;
756                case 126:
757                    mFrameSize = 1;
758                    break;
759                case 127:
760                    mFrameSize = 1;
761                    break;
762                default:
763                    CHECK(!"Should not be here, invalid offset.");
764                    break;
765            }
766
767            if (!mID) {
768                break;
769            }
770
771            String8 id;
772            getID(&id);
773
774            if (id == mID) {
775                break;
776            }
777        }
778
779        mOffset += mFrameSize;
780    }
781}
782
783static size_t StringSize(const uint8_t *start, uint8_t encoding) {
784    if (encoding == 0x00 || encoding == 0x03) {
785        // ISO 8859-1 or UTF-8
786        return strlen((const char *)start) + 1;
787    }
788
789    // UCS-2
790    size_t n = 0;
791    while (start[n] != '\0' || start[n + 1] != '\0') {
792        n += 2;
793    }
794
795    // Add size of null termination.
796    return n + 2;
797}
798
799const void *
800ID3::getAlbumArt(size_t *length, String8 *mime) const {
801    *length = 0;
802    mime->setTo("");
803
804    Iterator it(
805            *this,
806            (mVersion == ID3_V2_3 || mVersion == ID3_V2_4) ? "APIC" : "PIC");
807
808    while (!it.done()) {
809        size_t size;
810        const uint8_t *data = it.getData(&size);
811
812        if (mVersion == ID3_V2_3 || mVersion == ID3_V2_4) {
813            uint8_t encoding = data[0];
814            mime->setTo((const char *)&data[1]);
815            size_t mimeLen = strlen((const char *)&data[1]) + 1;
816
817            uint8_t picType = data[1 + mimeLen];
818#if 0
819            if (picType != 0x03) {
820                // Front Cover Art
821                it.next();
822                continue;
823            }
824#endif
825
826            size_t descLen = StringSize(&data[2 + mimeLen], encoding);
827
828            *length = size - 2 - mimeLen - descLen;
829
830            return &data[2 + mimeLen + descLen];
831        } else {
832            uint8_t encoding = data[0];
833
834            if (!memcmp(&data[1], "PNG", 3)) {
835                mime->setTo("image/png");
836            } else if (!memcmp(&data[1], "JPG", 3)) {
837                mime->setTo("image/jpeg");
838            } else if (!memcmp(&data[1], "-->", 3)) {
839                mime->setTo("text/plain");
840            } else {
841                return NULL;
842            }
843
844#if 0
845            uint8_t picType = data[4];
846            if (picType != 0x03) {
847                // Front Cover Art
848                it.next();
849                continue;
850            }
851#endif
852
853            size_t descLen = StringSize(&data[5], encoding);
854
855            *length = size - 5 - descLen;
856
857            return &data[5 + descLen];
858        }
859    }
860
861    return NULL;
862}
863
864bool ID3::parseV1(const sp<DataSource> &source) {
865    const size_t V1_TAG_SIZE = 128;
866
867    off64_t size;
868    if (source->getSize(&size) != OK || size < (off64_t)V1_TAG_SIZE) {
869        return false;
870    }
871
872    mData = (uint8_t *)malloc(V1_TAG_SIZE);
873    if (source->readAt(size - V1_TAG_SIZE, mData, V1_TAG_SIZE)
874            != (ssize_t)V1_TAG_SIZE) {
875        free(mData);
876        mData = NULL;
877
878        return false;
879    }
880
881    if (memcmp("TAG", mData, 3)) {
882        free(mData);
883        mData = NULL;
884
885        return false;
886    }
887
888    mSize = V1_TAG_SIZE;
889    mFirstFrameOffset = 3;
890
891    if (mData[V1_TAG_SIZE - 3] != 0) {
892        mVersion = ID3_V1;
893    } else {
894        mVersion = ID3_V1_1;
895    }
896
897    return true;
898}
899
900}  // namespace android
901