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Commit 89aa8fe4 authored by Andreas Huber's avatar Andreas Huber
Browse files

Remove an O(n^2) algorithm in MPEG4Extractor.cpp to speed up seeks in long streams 

containing B-frames.

Change-Id: Ie4dc734d2c2d5a5ce84674bb883f4b27e2278642
related-to-bug: 5336497
parent 84ada693

media/libstagefright/SampleTable.cpp

+80 −21
Original line number Diff line number Diff line
@@ -23,8 +23,8 @@ 


#include <arpa/inet.h>



#include <media/stagefright/foundation/ADebug.h>

#include <media/stagefright/DataSource.h>

#include <media/stagefright/MediaDebug.h>

#include <media/stagefright/Utils.h>



namespace android {
@@ -40,6 +40,71 @@ const uint32_t SampleTable::kSampleSizeTypeCompact = FOURCC('s', 't', 'z', '2'); 


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



struct SampleTable::CompositionDeltaLookup {

    CompositionDeltaLookup();



    void setEntries(

            const uint32_t *deltaEntries, size_t numDeltaEntries);



    uint32_t getCompositionTimeOffset(uint32_t sampleIndex);



private:

    Mutex mLock;



    const uint32_t *mDeltaEntries;

    size_t mNumDeltaEntries;



    size_t mCurrentDeltaEntry;

    size_t mCurrentEntrySampleIndex;



    DISALLOW_EVIL_CONSTRUCTORS(CompositionDeltaLookup);

};



SampleTable::CompositionDeltaLookup::CompositionDeltaLookup()

    : mDeltaEntries(NULL),

      mNumDeltaEntries(0),

      mCurrentDeltaEntry(0),

      mCurrentEntrySampleIndex(0) {

}



void SampleTable::CompositionDeltaLookup::setEntries(

        const uint32_t *deltaEntries, size_t numDeltaEntries) {

    Mutex::Autolock autolock(mLock);



    mDeltaEntries = deltaEntries;

    mNumDeltaEntries = numDeltaEntries;

    mCurrentDeltaEntry = 0;

    mCurrentEntrySampleIndex = 0;

}



uint32_t SampleTable::CompositionDeltaLookup::getCompositionTimeOffset(

        uint32_t sampleIndex) {

    Mutex::Autolock autolock(mLock);



    if (mDeltaEntries == NULL) {

        return 0;

    }



    if (sampleIndex < mCurrentEntrySampleIndex) {

        mCurrentDeltaEntry = 0;

        mCurrentEntrySampleIndex = 0;

    }



    while (mCurrentDeltaEntry < mNumDeltaEntries) {

        uint32_t sampleCount = mDeltaEntries[2 * mCurrentDeltaEntry];

        if (sampleIndex < mCurrentEntrySampleIndex + sampleCount) {

            return mDeltaEntries[2 * mCurrentDeltaEntry + 1];

        }



        mCurrentEntrySampleIndex += sampleCount;

        ++mCurrentDeltaEntry;

    }



    return 0;

}



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



SampleTable::SampleTable(const sp<DataSource> &source)

    : mDataSource(source),

      mChunkOffsetOffset(-1),
@@ -56,6 +121,7 @@ SampleTable::SampleTable(const sp<DataSource> &source) 
      mSampleTimeEntries(NULL),

      mCompositionTimeDeltaEntries(NULL),

      mNumCompositionTimeDeltaEntries(0),

      mCompositionDeltaLookup(new CompositionDeltaLookup),

      mSyncSampleOffset(-1),

      mNumSyncSamples(0),

      mSyncSamples(NULL),
@@ -71,6 +137,9 @@ SampleTable::~SampleTable() { 
    delete[] mSyncSamples;

    mSyncSamples = NULL;



    delete mCompositionDeltaLookup;

    mCompositionDeltaLookup = NULL;



    delete[] mCompositionTimeDeltaEntries;

    mCompositionTimeDeltaEntries = NULL;
@@ -318,6 +387,9 @@ status_t SampleTable::setCompositionTimeToSampleParams( 
        mCompositionTimeDeltaEntries[i] = ntohl(mCompositionTimeDeltaEntries[i]);

    }



    mCompositionDeltaLookup->setEntries(

            mCompositionTimeDeltaEntries, mNumCompositionTimeDeltaEntries);



    return OK;

}
@@ -430,8 +502,12 @@ void SampleTable::buildSampleEntriesTable() { 


                mSampleTimeEntries[sampleIndex].mSampleIndex = sampleIndex;



                uint32_t compTimeDelta =

                    mCompositionDeltaLookup->getCompositionTimeOffset(

                            sampleIndex);



                mSampleTimeEntries[sampleIndex].mCompositionTime =

                    sampleTime + getCompositionTimeOffset(sampleIndex);

                    sampleTime + compTimeDelta;

            }



            ++sampleIndex;
@@ -739,25 +815,8 @@ status_t SampleTable::getMetaDataForSample( 
    return OK;

}



uint32_t SampleTable::getCompositionTimeOffset(uint32_t sampleIndex) const {

    if (mCompositionTimeDeltaEntries == NULL) {

        return 0;

    }



    uint32_t curSample = 0;

    for (size_t i = 0; i < mNumCompositionTimeDeltaEntries; ++i) {

        uint32_t sampleCount = mCompositionTimeDeltaEntries[2 * i];



        if (sampleIndex < curSample + sampleCount) {

            uint32_t sampleDelta = mCompositionTimeDeltaEntries[2 * i + 1];



            return sampleDelta;

        }



        curSample += sampleCount;

    }



    return 0;

uint32_t SampleTable::getCompositionTimeOffset(uint32_t sampleIndex) {

    return mCompositionDeltaLookup->getCompositionTimeOffset(sampleIndex);

}



}  // namespace android

media/libstagefright/include/SampleTable.h

+4 −2
Original line number Diff line number Diff line
@@ -86,6 +86,8 @@ protected: 
    ~SampleTable();



private:

    struct CompositionDeltaLookup;



    static const uint32_t kChunkOffsetType32;

    static const uint32_t kChunkOffsetType64;

    static const uint32_t kSampleSizeType32;
@@ -117,6 +119,7 @@ private: 


    uint32_t *mCompositionTimeDeltaEntries;

    size_t mNumCompositionTimeDeltaEntries;

    CompositionDeltaLookup *mCompositionDeltaLookup;



    off64_t mSyncSampleOffset;

    uint32_t mNumSyncSamples;
@@ -135,8 +138,7 @@ private: 
    friend struct SampleIterator;



    status_t getSampleSize_l(uint32_t sample_index, size_t *sample_size);



    uint32_t getCompositionTimeOffset(uint32_t sampleIndex) const;

    uint32_t getCompositionTimeOffset(uint32_t sampleIndex);



    static int CompareIncreasingTime(const void *, const void *);