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Commit 22b37fa6 authored by James Dong's avatar James Dong
Browse files

File writer size estimation improvement 

o Do not count the reserved space for moov if the meta data size is small
o Do not count the extra 1KB disturbing small file estimation.
o Reduce the default minimum reserved space from 4 KB to 3 KB.
o Estimate the moov size based on both duration AND file size limit is set
  and set it to the smaller estimated value.

low risk change

bug - 3111983

Change-Id: I6ac2adb979d8cc12d6b4f1813d000c989add0199
parent f4cd9be0

include/media/stagefright/MPEG4Writer.h

+1 −0
Original line number Diff line number Diff line
@@ -152,6 +152,7 @@ private: 
    bool exceedsFileSizeLimit();

    bool use32BitFileOffset() const;

    bool exceedsFileDurationLimit();

    bool isFileStreamable() const;

    void trackProgressStatus(const Track* track, int64_t timeUs, status_t err = OK);



    MPEG4Writer(const MPEG4Writer &);

media/libstagefright/MPEG4Writer.cpp

+38 −18
Original line number Diff line number Diff line
@@ -309,11 +309,10 @@ int64_t MPEG4Writer::estimateMoovBoxSize(int32_t bitRate) { 
    //

    // Statistical analysis shows that metadata usually accounts

    // for a small portion of the total file size, usually < 0.6%.

    // Currently, lets set to 0.4% for now.



    // The default MIN_MOOV_BOX_SIZE is set to 0.4% x 1MB,

    // The default MIN_MOOV_BOX_SIZE is set to 0.6% x 1MB / 2,

    // where 1MB is the common file size limit for MMS application.

    // The default MAX _MOOV_BOX_SIZE value is based on about 4

    // The default MAX _MOOV_BOX_SIZE value is based on about 3

    // minute video recording with a bit rate about 3 Mbps, because

    // statistics also show that most of the video captured are going

    // to be less than 3 minutes.
@@ -321,20 +320,33 @@ int64_t MPEG4Writer::estimateMoovBoxSize(int32_t bitRate) { 
    // If the estimation is wrong, we will pay the price of wasting

    // some reserved space. This should not happen so often statistically.

    static const int32_t factor = mUse32BitOffset? 1: 2;

    static const int64_t MIN_MOOV_BOX_SIZE = 4 * 1024;  // 4 KB

    static const int64_t MIN_MOOV_BOX_SIZE = 3 * 1024;  // 3 KB

    static const int64_t MAX_MOOV_BOX_SIZE = (180 * 3000000 * 6LL / 8000);

    int64_t size = MIN_MOOV_BOX_SIZE;



    // Max file size limit is set

    if (mMaxFileSizeLimitBytes != 0 && mIsFileSizeLimitExplicitlyRequested) {

        size = mMaxFileSizeLimitBytes * 4 / 1000;

    } else if (mMaxFileDurationLimitUs != 0) {

        if (bitRate <= 0) {

            // We could not estimate the file size since bitRate is not set.

            size = MIN_MOOV_BOX_SIZE;

        size = mMaxFileSizeLimitBytes * 6 / 1000;

    }



    // Max file duration limit is set

    if (mMaxFileDurationLimitUs != 0) {

        if (bitRate > 0) {

            int64_t size2 =

                ((mMaxFileDurationLimitUs * bitRate * 6) / 1000 / 8000000);

            if (mMaxFileSizeLimitBytes != 0 && mIsFileSizeLimitExplicitlyRequested) {

                // When both file size and duration limits are set,

                // we use the smaller limit of the two.

                if (size > size2) {

                    size = size2;

                }

            } else {

            size = ((mMaxFileDurationLimitUs * bitRate * 4) / 1000 / 8000000);

                // Only max file duration limit is set

                size = size2;

            }

        }

    }



    if (size < MIN_MOOV_BOX_SIZE) {

        size = MIN_MOOV_BOX_SIZE;

    }
@@ -787,6 +799,10 @@ void MPEG4Writer::write(const void *data, size_t size) { 
    write(data, 1, size, mFile);

}



bool MPEG4Writer::isFileStreamable() const {

    return mStreamableFile;

}



bool MPEG4Writer::exceedsFileSizeLimit() {

    // No limit

    if (mMaxFileSizeLimitBytes == 0) {
@@ -799,7 +815,7 @@ bool MPEG4Writer::exceedsFileSizeLimit() { 
        nTotalBytesEstimate += (*it)->getEstimatedTrackSizeBytes();

    }



    return (nTotalBytesEstimate  + 1024 >= mMaxFileSizeLimitBytes);

    return (nTotalBytesEstimate >= mMaxFileSizeLimitBytes);

}



bool MPEG4Writer::exceedsFileDurationLimit() {
@@ -887,13 +903,17 @@ void MPEG4Writer::Track::updateTrackSizeEstimate() { 


    int64_t stszBoxSizeBytes = mSamplesHaveSameSize? 4: (mNumSamples * 4);



    mEstimatedTrackSizeBytes = mMdatSizeBytes +             // media data size

                               mNumStscTableEntries * 12 +  // stsc box size

    mEstimatedTrackSizeBytes = mMdatSizeBytes;  // media data size

    if (!mOwner->isFileStreamable()) {

        // Reserved free space is not large enough to hold

        // all meta data and thus wasted.

        mEstimatedTrackSizeBytes += mNumStscTableEntries * 12 +  // stsc box size

                                    mNumStssTableEntries * 4 +   // stss box size

                                    mNumSttsTableEntries * 8 +   // stts box size

                                    stcoBoxSizeBytes +           // stco box size

                                    stszBoxSizeBytes;            // stsz box size

    }

}



void MPEG4Writer::Track::addOneStscTableEntry(

        size_t chunkId, size_t sampleId) {