/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//#define LOG_NDEBUG 0
#define LOG_TAG "MatroskaExtractor"
#include <utils/Log.h>

#include "MatroskaExtractor.h"

#include <media/stagefright/foundation/ADebug.h>
#include <media/stagefright/foundation/hexdump.h>
#include <media/stagefright/DataSource.h>
#include <media/stagefright/MediaBuffer.h>
#include <media/stagefright/MediaDefs.h>
#include <media/stagefright/MediaErrors.h>
#include <media/stagefright/MediaSource.h>
#include <media/stagefright/MetaData.h>
#include <media/stagefright/Utils.h>
#include <utils/String8.h>

#include <inttypes.h>

namespace android {

struct DataSourceReader : public mkvparser::IMkvReader {
    DataSourceReader(const sp<DataSource> &source)
        : mSource(source) {
    }

    virtual int Read(long long position, long length, unsigned char* buffer) {
        CHECK(position >= 0);
        CHECK(length >= 0);

        if (length == 0) {
            return 0;
        }

        ssize_t n = mSource->readAt(position, buffer, length);

        if (n <= 0) {
            return -1;
        }

        return 0;
    }

    virtual int Length(long long* total, long long* available) {
        off64_t size;
        if (mSource->getSize(&size) != OK) {
            *total = -1;
            *available = (long long)((1ull << 63) - 1);

            return 0;
        }

        if (total) {
            *total = size;
        }

        if (available) {
            *available = size;
        }

        return 0;
    }

private:
    sp<DataSource> mSource;

    DataSourceReader(const DataSourceReader &);
    DataSourceReader &operator=(const DataSourceReader &);
};

////////////////////////////////////////////////////////////////////////////////

struct BlockIterator {
    BlockIterator(MatroskaExtractor *extractor, unsigned long trackNum, unsigned long index);

    bool eos() const;

    void advance();
    void reset();

    void seek(
            int64_t seekTimeUs, bool isAudio,
            int64_t *actualFrameTimeUs);

    const mkvparser::Block *block() const;
    int64_t blockTimeUs() const;

private:
    MatroskaExtractor *mExtractor;
    long long mTrackNum;
    unsigned long mIndex;

    const mkvparser::Cluster *mCluster;
    const mkvparser::BlockEntry *mBlockEntry;
    long mBlockEntryIndex;

    void advance_l();

    BlockIterator(const BlockIterator &);
    BlockIterator &operator=(const BlockIterator &);
};

struct MatroskaSource : public MediaSource {
    MatroskaSource(
            const sp<MatroskaExtractor> &extractor, size_t index);

    virtual status_t start(MetaData *params);
    virtual status_t stop();

    virtual sp<MetaData> getFormat();

    virtual status_t read(
            MediaBuffer **buffer, const ReadOptions *options);

protected:
    virtual ~MatroskaSource();

private:
    enum Type {
        AVC,
        AAC,
        OTHER
    };

    sp<MatroskaExtractor> mExtractor;
    size_t mTrackIndex;
    Type mType;
    bool mIsAudio;
    BlockIterator mBlockIter;
    size_t mNALSizeLen;  // for type AVC

    List<MediaBuffer *> mPendingFrames;

    status_t advance();

    status_t readBlock();
    void clearPendingFrames();

    MatroskaSource(const MatroskaSource &);
    MatroskaSource &operator=(const MatroskaSource &);
};

const mkvparser::Track* MatroskaExtractor::TrackInfo::getTrack() const {
    return mExtractor->mSegment->GetTracks()->GetTrackByNumber(mTrackNum);
}

// This function does exactly the same as mkvparser::Cues::Find, except that it
// searches in our own track based vectors. We should not need this once mkvparser
// adds the same functionality.
const mkvparser::CuePoint::TrackPosition *MatroskaExtractor::TrackInfo::find(
        long long timeNs) const {
    ALOGV("mCuePoints.size %zu", mCuePoints.size());
    if (mCuePoints.empty()) {
        return NULL;
    }

    const mkvparser::CuePoint* cp = mCuePoints.itemAt(0);
    const mkvparser::Track* track = getTrack();
    if (timeNs <= cp->GetTime(mExtractor->mSegment)) {
        return cp->Find(track);
    }

    // Binary searches through relevant cues; assumes cues are ordered by timecode.
    // If we do detect out-of-order cues, return NULL.
    size_t lo = 0;
    size_t hi = mCuePoints.size();
    while (lo < hi) {
        const size_t mid = lo + (hi - lo) / 2;
        const mkvparser::CuePoint* const midCp = mCuePoints.itemAt(mid);
        const long long cueTimeNs = midCp->GetTime(mExtractor->mSegment);
        if (cueTimeNs <= timeNs) {
            lo = mid + 1;
        } else {
            hi = mid;
        }
    }

    if (lo == 0) {
        return NULL;
    }

    cp = mCuePoints.itemAt(lo - 1);
    if (cp->GetTime(mExtractor->mSegment) > timeNs) {
        return NULL;
    }

    return cp->Find(track);
}

MatroskaSource::MatroskaSource(
        const sp<MatroskaExtractor> &extractor, size_t index)
    : mExtractor(extractor),
      mTrackIndex(index),
      mType(OTHER),
      mIsAudio(false),
      mBlockIter(mExtractor.get(),
                 mExtractor->mTracks.itemAt(index).mTrackNum,
                 index),
      mNALSizeLen(0) {
    sp<MetaData> meta = mExtractor->mTracks.itemAt(index).mMeta;

    const char *mime;
    CHECK(meta->findCString(kKeyMIMEType, &mime));

    mIsAudio = !strncasecmp("audio/", mime, 6);

    if (!strcasecmp(mime, MEDIA_MIMETYPE_VIDEO_AVC)) {
        mType = AVC;

        uint32_t dummy;
        const uint8_t *avcc;
        size_t avccSize;
        CHECK(meta->findData(
                    kKeyAVCC, &dummy, (const void **)&avcc, &avccSize));

        CHECK_GE(avccSize, 5u);

        mNALSizeLen = 1 + (avcc[4] & 3);
        ALOGV("mNALSizeLen = %zu", mNALSizeLen);
    } else if (!strcasecmp(mime, MEDIA_MIMETYPE_AUDIO_AAC)) {
        mType = AAC;
    }
}

MatroskaSource::~MatroskaSource() {
    clearPendingFrames();
}

status_t MatroskaSource::start(MetaData * /* params */) {
    mBlockIter.reset();

    return OK;
}

status_t MatroskaSource::stop() {
    clearPendingFrames();

    return OK;
}

sp<MetaData> MatroskaSource::getFormat() {
    return mExtractor->mTracks.itemAt(mTrackIndex).mMeta;
}

////////////////////////////////////////////////////////////////////////////////

BlockIterator::BlockIterator(
        MatroskaExtractor *extractor, unsigned long trackNum, unsigned long index)
    : mExtractor(extractor),
      mTrackNum(trackNum),
      mIndex(index),
      mCluster(NULL),
      mBlockEntry(NULL),
      mBlockEntryIndex(0) {
    reset();
}

bool BlockIterator::eos() const {
    return mCluster == NULL || mCluster->EOS();
}

void BlockIterator::advance() {
    Mutex::Autolock autoLock(mExtractor->mLock);
    advance_l();
}

void BlockIterator::advance_l() {
    for (;;) {
        long res = mCluster->GetEntry(mBlockEntryIndex, mBlockEntry);
        ALOGV("GetEntry returned %ld", res);

        long long pos;
        long len;
        if (res < 0) {
            // Need to parse this cluster some more

            CHECK_EQ(res, mkvparser::E_BUFFER_NOT_FULL);

            res = mCluster->Parse(pos, len);
            ALOGV("Parse returned %ld", res);

            if (res < 0) {
                // I/O error

                ALOGE("Cluster::Parse returned result %ld", res);

                mCluster = NULL;
                break;
            }

            continue;
        } else if (res == 0) {
            // We're done with this cluster

            const mkvparser::Cluster *nextCluster;
            res = mExtractor->mSegment->ParseNext(
                    mCluster, nextCluster, pos, len);
            ALOGV("ParseNext returned %ld", res);

            if (res != 0) {
                // EOF or error

                mCluster = NULL;
                break;
            }

            CHECK_EQ(res, 0);
            CHECK(nextCluster != NULL);
            CHECK(!nextCluster->EOS());

            mCluster = nextCluster;

            res = mCluster->Parse(pos, len);
            ALOGV("Parse (2) returned %ld", res);
            CHECK_GE(res, 0);

            mBlockEntryIndex = 0;
            continue;
        }

        CHECK(mBlockEntry != NULL);
        CHECK(mBlockEntry->GetBlock() != NULL);
        ++mBlockEntryIndex;

        if (mBlockEntry->GetBlock()->GetTrackNumber() == mTrackNum) {
            break;
        }
    }
}

void BlockIterator::reset() {
    Mutex::Autolock autoLock(mExtractor->mLock);

    mCluster = mExtractor->mSegment->GetFirst();
    mBlockEntry = NULL;
    mBlockEntryIndex = 0;

    do {
        advance_l();
    } while (!eos() && block()->GetTrackNumber() != mTrackNum);
}

void BlockIterator::seek(
        int64_t seekTimeUs, bool isAudio,
        int64_t *actualFrameTimeUs) {
    Mutex::Autolock autoLock(mExtractor->mLock);

    *actualFrameTimeUs = -1ll;

    const int64_t seekTimeNs = seekTimeUs * 1000ll - mExtractor->mSeekPreRollNs;

    mkvparser::Segment* const pSegment = mExtractor->mSegment;

    // Special case the 0 seek to avoid loading Cues when the application
    // extraneously seeks to 0 before playing.
    if (seekTimeNs <= 0) {
        ALOGV("Seek to beginning: %" PRId64, seekTimeUs);
        mCluster = pSegment->GetFirst();
        mBlockEntryIndex = 0;
        do {
            advance_l();
        } while (!eos() && block()->GetTrackNumber() != mTrackNum);
        return;
    }

    ALOGV("Seeking to: %" PRId64, seekTimeUs);

    // If the Cues have not been located then find them.
    const mkvparser::Cues* pCues = pSegment->GetCues();
    const mkvparser::SeekHead* pSH = pSegment->GetSeekHead();
    if (!pCues && pSH) {
        const size_t count = pSH->GetCount();
        const mkvparser::SeekHead::Entry* pEntry;
        ALOGV("No Cues yet");

        for (size_t index = 0; index < count; index++) {
            pEntry = pSH->GetEntry(index);

            if (pEntry->id == 0x0C53BB6B) { // Cues ID
                long len; long long pos;
                pSegment->ParseCues(pEntry->pos, pos, len);
                pCues = pSegment->GetCues();
                ALOGV("Cues found");
                break;
            }
        }

        if (!pCues) {
            ALOGE("No Cues in file");
            return;
        }
    }
    else if (!pSH) {
        ALOGE("No SeekHead");
        return;
    }

    const mkvparser::CuePoint* pCP;
    mkvparser::Tracks const *pTracks = pSegment->GetTracks();
    while (!pCues->DoneParsing()) {
        pCues->LoadCuePoint();
        pCP = pCues->GetLast();
        CHECK(pCP);

        size_t trackCount = mExtractor->mTracks.size();
        for (size_t index = 0; index < trackCount; ++index) {
            MatroskaExtractor::TrackInfo& track = mExtractor->mTracks.editItemAt(index);
            const mkvparser::Track *pTrack = pTracks->GetTrackByNumber(track.mTrackNum);
            if (pTrack && pTrack->GetType() == 1 && pCP->Find(pTrack)) { // VIDEO_TRACK
                track.mCuePoints.push_back(pCP);
            }
        }

        if (pCP->GetTime(pSegment) >= seekTimeNs) {
            ALOGV("Parsed past relevant Cue");
            break;
        }
    }

    const mkvparser::CuePoint::TrackPosition *pTP = NULL;
    const mkvparser::Track *thisTrack = pTracks->GetTrackByNumber(mTrackNum);
    if (thisTrack->GetType() == 1) { // video
        MatroskaExtractor::TrackInfo& track = mExtractor->mTracks.editItemAt(mIndex);
        pTP = track.find(seekTimeNs);
    } else {
        // The Cue index is built around video keyframes
        unsigned long int trackCount = pTracks->GetTracksCount();
        for (size_t index = 0; index < trackCount; ++index) {
            const mkvparser::Track *pTrack = pTracks->GetTrackByIndex(index);
            if (pTrack && pTrack->GetType() == 1 && pCues->Find(seekTimeNs, pTrack, pCP, pTP)) {
                ALOGV("Video track located at %zu", index);
                break;
            }
        }
    }


    // Always *search* based on the video track, but finalize based on mTrackNum
    if (!pTP) {
        ALOGE("Did not locate the video track for seeking");
        return;
    }

    mCluster = pSegment->FindOrPreloadCluster(pTP->m_pos);

    CHECK(mCluster);
    CHECK(!mCluster->EOS());

    // mBlockEntryIndex starts at 0 but m_block starts at 1
    CHECK_GT(pTP->m_block, 0);
    mBlockEntryIndex = pTP->m_block - 1;

    for (;;) {
        advance_l();

        if (eos()) break;

        if (isAudio || block()->IsKey()) {
            // Accept the first key frame
            int64_t frameTimeUs = (block()->GetTime(mCluster) + 500LL) / 1000LL;
            if (thisTrack->GetType() == 1 || frameTimeUs >= seekTimeUs) {
                *actualFrameTimeUs = frameTimeUs;
                ALOGV("Requested seek point: %" PRId64 " actual: %" PRId64,
                      seekTimeUs, *actualFrameTimeUs);
                break;
            }
        }
    }
}

const mkvparser::Block *BlockIterator::block() const {
    CHECK(!eos());

    return mBlockEntry->GetBlock();
}

int64_t BlockIterator::blockTimeUs() const {
    return (mBlockEntry->GetBlock()->GetTime(mCluster) + 500ll) / 1000ll;
}

////////////////////////////////////////////////////////////////////////////////

static unsigned U24_AT(const uint8_t *ptr) {
    return ptr[0] << 16 | ptr[1] << 8 | ptr[2];
}

void MatroskaSource::clearPendingFrames() {
    while (!mPendingFrames.empty()) {
        MediaBuffer *frame = *mPendingFrames.begin();
        mPendingFrames.erase(mPendingFrames.begin());

        frame->release();
        frame = NULL;
    }
}

status_t MatroskaSource::readBlock() {
    CHECK(mPendingFrames.empty());

    if (mBlockIter.eos()) {
        return ERROR_END_OF_STREAM;
    }

    const mkvparser::Block *block = mBlockIter.block();

    int64_t timeUs = mBlockIter.blockTimeUs();

    for (int i = 0; i < block->GetFrameCount(); ++i) {
        const mkvparser::Block::Frame &frame = block->GetFrame(i);

        MediaBuffer *mbuf = new MediaBuffer(frame.len);
        mbuf->meta_data()->setInt64(kKeyTime, timeUs);
        mbuf->meta_data()->setInt32(kKeyIsSyncFrame, block->IsKey());

        long n = frame.Read(mExtractor->mReader, (unsigned char *)mbuf->data());
        if (n != 0) {
            mPendingFrames.clear();

            mBlockIter.advance();
            return ERROR_IO;
        }

        mPendingFrames.push_back(mbuf);
    }

    mBlockIter.advance();

    return OK;
}

status_t MatroskaSource::read(
        MediaBuffer **out, const ReadOptions *options) {
    *out = NULL;

    int64_t targetSampleTimeUs = -1ll;

    int64_t seekTimeUs;
    ReadOptions::SeekMode mode;
    if (options && options->getSeekTo(&seekTimeUs, &mode)
            && !mExtractor->isLiveStreaming()) {
        clearPendingFrames();

        // The audio we want is located by using the Cues to seek the video
        // stream to find the target Cluster then iterating to finalize for
        // audio.
        int64_t actualFrameTimeUs;
        mBlockIter.seek(seekTimeUs, mIsAudio, &actualFrameTimeUs);

        if (mode == ReadOptions::SEEK_CLOSEST) {
            targetSampleTimeUs = actualFrameTimeUs;
        }
    }

    while (mPendingFrames.empty()) {
        status_t err = readBlock();

        if (err != OK) {
            clearPendingFrames();

            return err;
        }
    }

    MediaBuffer *frame = *mPendingFrames.begin();
    mPendingFrames.erase(mPendingFrames.begin());

    if (mType != AVC) {
        if (targetSampleTimeUs >= 0ll) {
            frame->meta_data()->setInt64(
                    kKeyTargetTime, targetSampleTimeUs);
        }

        *out = frame;

        return OK;
    }

    // Each input frame contains one or more NAL fragments, each fragment
    // is prefixed by mNALSizeLen bytes giving the fragment length,
    // followed by a corresponding number of bytes containing the fragment.
    // We output all these fragments into a single large buffer separated
    // by startcodes (0x00 0x00 0x00 0x01).

    const uint8_t *srcPtr =
        (const uint8_t *)frame->data() + frame->range_offset();

    size_t srcSize = frame->range_length();

    size_t dstSize = 0;
    MediaBuffer *buffer = NULL;
    uint8_t *dstPtr = NULL;

    for (int32_t pass = 0; pass < 2; ++pass) {
        size_t srcOffset = 0;
        size_t dstOffset = 0;
        while (srcOffset + mNALSizeLen <= srcSize) {
            size_t NALsize;
            switch (mNALSizeLen) {
                case 1: NALsize = srcPtr[srcOffset]; break;
                case 2: NALsize = U16_AT(srcPtr + srcOffset); break;
                case 3: NALsize = U24_AT(srcPtr + srcOffset); break;
                case 4: NALsize = U32_AT(srcPtr + srcOffset); break;
                default:
                    TRESPASS();
            }

            if (srcOffset + mNALSizeLen + NALsize > srcSize) {
                break;
            }

            if (pass == 1) {
                memcpy(&dstPtr[dstOffset], "\x00\x00\x00\x01", 4);

                memcpy(&dstPtr[dstOffset + 4],
                       &srcPtr[srcOffset + mNALSizeLen],
                       NALsize);
            }

            dstOffset += 4;  // 0x00 00 00 01
            dstOffset += NALsize;

            srcOffset += mNALSizeLen + NALsize;
        }

        if (srcOffset < srcSize) {
            // There were trailing bytes or not enough data to complete
            // a fragment.

            frame->release();
            frame = NULL;

            return ERROR_MALFORMED;
        }

        if (pass == 0) {
            dstSize = dstOffset;

            buffer = new MediaBuffer(dstSize);

            int64_t timeUs;
            CHECK(frame->meta_data()->findInt64(kKeyTime, &timeUs));
            int32_t isSync;
            CHECK(frame->meta_data()->findInt32(kKeyIsSyncFrame, &isSync));

            buffer->meta_data()->setInt64(kKeyTime, timeUs);
            buffer->meta_data()->setInt32(kKeyIsSyncFrame, isSync);

            dstPtr = (uint8_t *)buffer->data();
        }
    }

    frame->release();
    frame = NULL;

    if (targetSampleTimeUs >= 0ll) {
        buffer->meta_data()->setInt64(
                kKeyTargetTime, targetSampleTimeUs);
    }

    *out = buffer;

    return OK;
}

////////////////////////////////////////////////////////////////////////////////

MatroskaExtractor::MatroskaExtractor(const sp<DataSource> &source)
    : mDataSource(source),
      mReader(new DataSourceReader(mDataSource)),
      mSegment(NULL),
      mExtractedThumbnails(false),
      mIsWebm(false),
      mSeekPreRollNs(0) {
    off64_t size;
    mIsLiveStreaming =
        (mDataSource->flags()
            & (DataSource::kWantsPrefetching
                | DataSource::kIsCachingDataSource))
        && mDataSource->getSize(&size) != OK;

    mkvparser::EBMLHeader ebmlHeader;
    long long pos;
    if (ebmlHeader.Parse(mReader, pos) < 0) {
        return;
    }

    if (ebmlHeader.m_docType && !strcmp("webm", ebmlHeader.m_docType)) {
        mIsWebm = true;
    }

    long long ret =
        mkvparser::Segment::CreateInstance(mReader, pos, mSegment);

    if (ret) {
        CHECK(mSegment == NULL);
        return;
    }

    // from mkvparser::Segment::Load(), but stop at first cluster
    ret = mSegment->ParseHeaders();
    if (ret == 0) {
        long len;
        ret = mSegment->LoadCluster(pos, len);
        if (ret >= 1) {
            // no more clusters
            ret = 0;
        }
    } else if (ret > 0) {
        ret = mkvparser::E_BUFFER_NOT_FULL;
    }

    if (ret < 0) {
        ALOGW("Corrupt %s source: %s", mIsWebm ? "webm" : "matroska",
                uriDebugString(mDataSource->getUri()).c_str());
        delete mSegment;
        mSegment = NULL;
        return;
    }

#if 0
    const mkvparser::SegmentInfo *info = mSegment->GetInfo();
    ALOGI("muxing app: %s, writing app: %s",
         info->GetMuxingAppAsUTF8(),
         info->GetWritingAppAsUTF8());
#endif

    addTracks();
}

MatroskaExtractor::~MatroskaExtractor() {
    delete mSegment;
    mSegment = NULL;

    delete mReader;
    mReader = NULL;
}

size_t MatroskaExtractor::countTracks() {
    return mTracks.size();
}

sp<MediaSource> MatroskaExtractor::getTrack(size_t index) {
    if (index >= mTracks.size()) {
        return NULL;
    }

    return new MatroskaSource(this, index);
}

sp<MetaData> MatroskaExtractor::getTrackMetaData(
        size_t index, uint32_t flags) {
    if (index >= mTracks.size()) {
        return NULL;
    }

    if ((flags & kIncludeExtensiveMetaData) && !mExtractedThumbnails
            && !isLiveStreaming()) {
        findThumbnails();
        mExtractedThumbnails = true;
    }

    return mTracks.itemAt(index).mMeta;
}

bool MatroskaExtractor::isLiveStreaming() const {
    return mIsLiveStreaming;
}

static int bytesForSize(size_t size) {
    // use at most 28 bits (4 times 7)
    CHECK(size <= 0xfffffff);

    if (size > 0x1fffff) {
        return 4;
    } else if (size > 0x3fff) {
        return 3;
    } else if (size > 0x7f) {
        return 2;
    }
    return 1;
}

static void storeSize(uint8_t *data, size_t &idx, size_t size) {
    int numBytes = bytesForSize(size);
    idx += numBytes;

    data += idx;
    size_t next = 0;
    while (numBytes--) {
        *--data = (size & 0x7f) | next;
        size >>= 7;
        next = 0x80;
    }
}

static void addESDSFromCodecPrivate(
        const sp<MetaData> &meta,
        bool isAudio, const void *priv, size_t privSize) {

    int privSizeBytesRequired = bytesForSize(privSize);
    int esdsSize2 = 14 + privSizeBytesRequired + privSize;
    int esdsSize2BytesRequired = bytesForSize(esdsSize2);
    int esdsSize1 = 4 + esdsSize2BytesRequired + esdsSize2;
    int esdsSize1BytesRequired = bytesForSize(esdsSize1);
    size_t esdsSize = 1 + esdsSize1BytesRequired + esdsSize1;
    uint8_t *esds = new uint8_t[esdsSize];

    size_t idx = 0;
    esds[idx++] = 0x03;
    storeSize(esds, idx, esdsSize1);
    esds[idx++] = 0x00; // ES_ID
    esds[idx++] = 0x00; // ES_ID
    esds[idx++] = 0x00; // streamDependenceFlag, URL_Flag, OCRstreamFlag
    esds[idx++] = 0x04;
    storeSize(esds, idx, esdsSize2);
    esds[idx++] = isAudio ? 0x40   // Audio ISO/IEC 14496-3
                          : 0x20;  // Visual ISO/IEC 14496-2
    for (int i = 0; i < 12; i++) {
        esds[idx++] = 0x00;
    }
    esds[idx++] = 0x05;
    storeSize(esds, idx, privSize);
    memcpy(esds + idx, priv, privSize);

    meta->setData(kKeyESDS, 0, esds, esdsSize);

    delete[] esds;
    esds = NULL;
}

status_t addVorbisCodecInfo(
        const sp<MetaData> &meta,
        const void *_codecPrivate, size_t codecPrivateSize) {
    // hexdump(_codecPrivate, codecPrivateSize);

    if (codecPrivateSize < 1) {
        return ERROR_MALFORMED;
    }

    const uint8_t *codecPrivate = (const uint8_t *)_codecPrivate;

    if (codecPrivate[0] != 0x02) {
        return ERROR_MALFORMED;
    }

    // codecInfo starts with two lengths, len1 and len2, that are
    // "Xiph-style-lacing encoded"...

    size_t offset = 1;
    size_t len1 = 0;
    while (offset < codecPrivateSize && codecPrivate[offset] == 0xff) {
        len1 += 0xff;
        ++offset;
    }
    if (offset >= codecPrivateSize) {
        return ERROR_MALFORMED;
    }
    len1 += codecPrivate[offset++];

    size_t len2 = 0;
    while (offset < codecPrivateSize && codecPrivate[offset] == 0xff) {
        len2 += 0xff;
        ++offset;
    }
    if (offset >= codecPrivateSize) {
        return ERROR_MALFORMED;
    }
    len2 += codecPrivate[offset++];

    if (codecPrivateSize < offset + len1 + len2) {
        return ERROR_MALFORMED;
    }

    if (codecPrivate[offset] != 0x01) {
        return ERROR_MALFORMED;
    }
    meta->setData(kKeyVorbisInfo, 0, &codecPrivate[offset], len1);

    offset += len1;
    if (codecPrivate[offset] != 0x03) {
        return ERROR_MALFORMED;
    }

    offset += len2;
    if (codecPrivate[offset] != 0x05) {
        return ERROR_MALFORMED;
    }

    meta->setData(
            kKeyVorbisBooks, 0, &codecPrivate[offset],
            codecPrivateSize - offset);

    return OK;
}

void MatroskaExtractor::addTracks() {
    const mkvparser::Tracks *tracks = mSegment->GetTracks();

    for (size_t index = 0; index < tracks->GetTracksCount(); ++index) {
        const mkvparser::Track *track = tracks->GetTrackByIndex(index);

        if (track == NULL) {
            // Apparently this is currently valid (if unexpected) behaviour
            // of the mkv parser lib.
            continue;
        }

        const char *const codecID = track->GetCodecId();
        ALOGV("codec id = %s", codecID);
        ALOGV("codec name = %s", track->GetCodecNameAsUTF8());

        size_t codecPrivateSize;
        const unsigned char *codecPrivate =
            track->GetCodecPrivate(codecPrivateSize);

        enum { VIDEO_TRACK = 1, AUDIO_TRACK = 2 };

        sp<MetaData> meta = new MetaData;

        status_t err = OK;

        switch (track->GetType()) {
            case VIDEO_TRACK:
            {
                const mkvparser::VideoTrack *vtrack =
                    static_cast<const mkvparser::VideoTrack *>(track);

                if (!strcmp("V_MPEG4/ISO/AVC", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);
                    meta->setData(kKeyAVCC, 0, codecPrivate, codecPrivateSize);
                } else if (!strcmp("V_MPEG4/ISO/ASP", codecID)) {
                    if (codecPrivateSize > 0) {
                        meta->setCString(
                                kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_MPEG4);
                        addESDSFromCodecPrivate(
                                meta, false, codecPrivate, codecPrivateSize);
                    } else {
                        ALOGW("%s is detected, but does not have configuration.",
                                codecID);
                        continue;
                    }
                } else if (!strcmp("V_VP8", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_VP8);
                } else if (!strcmp("V_VP9", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_VP9);
                } else {
                    ALOGW("%s is not supported.", codecID);
                    continue;
                }

                meta->setInt32(kKeyWidth, vtrack->GetWidth());
                meta->setInt32(kKeyHeight, vtrack->GetHeight());
                break;
            }

            case AUDIO_TRACK:
            {
                const mkvparser::AudioTrack *atrack =
                    static_cast<const mkvparser::AudioTrack *>(track);

                if (!strcmp("A_AAC", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_AAC);
                    CHECK(codecPrivateSize >= 2);

                    addESDSFromCodecPrivate(
                            meta, true, codecPrivate, codecPrivateSize);
                } else if (!strcmp("A_VORBIS", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_VORBIS);

                    err = addVorbisCodecInfo(
                            meta, codecPrivate, codecPrivateSize);
                } else if (!strcmp("A_OPUS", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_OPUS);
                    meta->setData(kKeyOpusHeader, 0, codecPrivate, codecPrivateSize);
                    meta->setInt64(kKeyOpusCodecDelay, track->GetCodecDelay());
                    meta->setInt64(kKeyOpusSeekPreRoll, track->GetSeekPreRoll());
                    mSeekPreRollNs = track->GetSeekPreRoll();
                } else if (!strcmp("A_MPEG/L3", codecID)) {
                    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_MPEG);
                } else {
                    ALOGW("%s is not supported.", codecID);
                    continue;
                }

                meta->setInt32(kKeySampleRate, atrack->GetSamplingRate());
                meta->setInt32(kKeyChannelCount, atrack->GetChannels());
                break;
            }

            default:
                continue;
        }

        if (err != OK) {
            ALOGE("skipping track, codec specific data was malformed.");
            continue;
        }

        long long durationNs = mSegment->GetDuration();
        meta->setInt64(kKeyDuration, (durationNs + 500) / 1000);

        mTracks.push();
        TrackInfo *trackInfo = &mTracks.editItemAt(mTracks.size() - 1);
        trackInfo->mTrackNum = track->GetNumber();
        trackInfo->mMeta = meta;
        trackInfo->mExtractor = this;
    }
}

void MatroskaExtractor::findThumbnails() {
    for (size_t i = 0; i < mTracks.size(); ++i) {
        TrackInfo *info = &mTracks.editItemAt(i);

        const char *mime;
        CHECK(info->mMeta->findCString(kKeyMIMEType, &mime));

        if (strncasecmp(mime, "video/", 6)) {
            continue;
        }

        BlockIterator iter(this, info->mTrackNum, i);
        int32_t j = 0;
        int64_t thumbnailTimeUs = 0;
        size_t maxBlockSize = 0;
        while (!iter.eos() && j < 20) {
            if (iter.block()->IsKey()) {
                ++j;

                size_t blockSize = 0;
                for (int k = 0; k < iter.block()->GetFrameCount(); ++k) {
                    blockSize += iter.block()->GetFrame(k).len;
                }

                if (blockSize > maxBlockSize) {
                    maxBlockSize = blockSize;
                    thumbnailTimeUs = iter.blockTimeUs();
                }
            }
            iter.advance();
        }
        info->mMeta->setInt64(kKeyThumbnailTime, thumbnailTimeUs);
    }
}

sp<MetaData> MatroskaExtractor::getMetaData() {
    sp<MetaData> meta = new MetaData;

    meta->setCString(
            kKeyMIMEType,
            mIsWebm ? "video/webm" : MEDIA_MIMETYPE_CONTAINER_MATROSKA);

    return meta;
}

uint32_t MatroskaExtractor::flags() const {
    uint32_t x = CAN_PAUSE;
    if (!isLiveStreaming()) {
        x |= CAN_SEEK_BACKWARD | CAN_SEEK_FORWARD | CAN_SEEK;
    }

    return x;
}

bool SniffMatroska(
        const sp<DataSource> &source, String8 *mimeType, float *confidence,
        sp<AMessage> *) {
    DataSourceReader reader(source);
    mkvparser::EBMLHeader ebmlHeader;
    long long pos;
    if (ebmlHeader.Parse(&reader, pos) < 0) {
        return false;
    }

    mimeType->setTo(MEDIA_MIMETYPE_CONTAINER_MATROSKA);
    *confidence = 0.6;

    return true;
}

}  // namespace android