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Commit e991e5f3 authored by James Dong's avatar James Dong
Browse files

Eliminate the linear cost associated with mSampleSizes.size() 

- The linear cost associated with mSampleSizes.size() call causes the
  CPU load to increase overtime as more and more audio/video samples
  are recorded.

- Other Lists used in the MP4 file writer may have similar issues, but
  the size() call is not made for each output audio/video output sample,
  or the size of the list is bounded (not linear to the total number
  of audio/video output samples). As for now, we can live with the small
  cost (tested with 30 minutes long recording).

Change-Id: I23bd93ea4256cb0be0c1649760e39e6809eb4946
parent b350bec5

media/libstagefright/MPEG4Writer.cpp

+15 −9
Original line number Diff line number Diff line
@@ -66,6 +66,10 @@ private: 


    pthread_t mThread;



    // mNumSamples is used to track how many samples in mSampleSizes List.

    // This is to reduce the cost associated with mSampleSizes.size() call,

    // since it is O(n). Ideally, the fix should be in List class.

    size_t              mNumSamples;

    List<size_t>        mSampleSizes;

    bool                mSamplesHaveSameSize;
@@ -942,6 +946,7 @@ void MPEG4Writer::Track::threadEntry() { 
    sp<MetaData> meta_data;

    bool collectStats = collectStatisticalData();



    mNumSamples = 0;

    status_t err = OK;

    MediaBuffer *buffer;

    while (!mDone && (err = mSource->read(&buffer)) == OK) {
@@ -1133,7 +1138,8 @@ void MPEG4Writer::Track::threadEntry() { 
        }



        mSampleSizes.push_back(sampleSize);

        if (mSampleSizes.size() > 2) {

        ++mNumSamples;

        if (mNumSamples > 2) {

            if (lastDurationUs != timestampUs - lastTimestampUs) {

                SttsTableEntry sttsEntry(sampleCount, lastDurationUs);

                mSttsTableEntries.push_back(sttsEntry);
@@ -1143,7 +1149,7 @@ void MPEG4Writer::Track::threadEntry() { 
            }

        }

        if (mSamplesHaveSameSize) {

            if (mSampleSizes.size() >= 2 && previousSampleSize != sampleSize) {

            if (mNumSamples >= 2 && previousSampleSize != sampleSize) {

                mSamplesHaveSameSize = false;

            }

            previousSampleSize = sampleSize;
@@ -1152,7 +1158,7 @@ void MPEG4Writer::Track::threadEntry() { 
        lastTimestampUs = timestampUs;



        if (isSync != 0) {

            mStssTableEntries.push_back(mSampleSizes.size());

            mStssTableEntries.push_back(mNumSamples);

        }



        if (mTrackingProgressStatus) {
@@ -1208,7 +1214,7 @@ void MPEG4Writer::Track::threadEntry() { 


    // Last chunk

    if (mOwner->numTracks() == 1) {

        StscTableEntry stscEntry(1, mSampleSizes.size(), 1);

        StscTableEntry stscEntry(1, mNumSamples, 1);

        mStscTableEntries.push_back(stscEntry);

    } else if (!mChunkSamples.empty()) {

        ++nChunks;
@@ -1220,7 +1226,7 @@ void MPEG4Writer::Track::threadEntry() { 
    // We don't really know how long the last frame lasts, since

    // there is no frame time after it, just repeat the previous

    // frame's duration.

    if (mSampleSizes.size() == 1) {

    if (mNumSamples == 1) {

        lastDurationUs = 0;  // A single sample's duration

    } else {

        ++sampleCount;  // Count for the last sample
@@ -1229,7 +1235,7 @@ void MPEG4Writer::Track::threadEntry() { 
    mSttsTableEntries.push_back(sttsEntry);

    mReachedEOS = true;

    LOGI("Received total/0-length (%d/%d) buffers and encoded %d frames - %s",

            count, nZeroLengthFrames, mSampleSizes.size(), is_audio? "audio": "video");

            count, nZeroLengthFrames, mNumSamples, is_audio? "audio": "video");



    logStatisticalData(is_audio);

}
@@ -1292,7 +1298,7 @@ void MPEG4Writer::trackProgressStatus( 
void MPEG4Writer::Track::findMinAvgMaxSampleDurationMs(

        int32_t *min, int32_t *avg, int32_t *max) {

    CHECK(!mSampleSizes.empty());

    int32_t avgSampleDurationMs = mMaxTimeStampUs / 1000 / mSampleSizes.size();

    int32_t avgSampleDurationMs = mMaxTimeStampUs / 1000 / mNumSamples;

    int32_t minSampleDurationMs = 0x7FFFFFFF;

    int32_t maxSampleDurationMs = 0;

    for (List<SttsTableEntry>::iterator it = mSttsTableEntries.begin();
@@ -1344,7 +1350,7 @@ void MPEG4Writer::Track::logStatisticalData(bool isAudio) { 
    if (collectStats) {

        LOGI("%s track - duration %lld us, total %d frames",

                isAudio? "audio": "video", mMaxTimeStampUs,

                mSampleSizes.size());

                mNumSamples);

        int32_t min, avg, max;

        findMinAvgMaxSampleDurationMs(&min, &avg, &max);

        LOGI("min/avg/max sample duration (ms): %d/%d/%d", min, avg, max);
@@ -1738,7 +1744,7 @@ void MPEG4Writer::Track::writeTrackHeader( 
            } else {

                mOwner->writeInt32(0);

            }

            mOwner->writeInt32(mSampleSizes.size());

            mOwner->writeInt32(mNumSamples);

            if (!mSamplesHaveSameSize) {

                for (List<size_t>::iterator it = mSampleSizes.begin();

                     it != mSampleSizes.end(); ++it) {