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Commit 4c682b8d authored by Gopalakrishnan Nallasamy's avatar Gopalakrishnan Nallasamy
Browse files

MPEG4Extractor: Keep CTS values positive 

Media files with zero STTS delta in video track exists, probably malformed files. If the same
video track has edit shift entry to shift(prepone) video frames, then CTS could get negative.
Since negative CTS values are not meaningful, this CL fixes that by only subtracting the lower
of CTS and edit shift value from CTS.

Bug: 117402420

Test: cts-tradefed run cts-dev -m CtsMediaTestCases --compatibility:module-arg CtsMediaTestCases:
      include-annotation:android.platform.test.annotations.RequiresDevice

Change-Id: I49657457f90e9bbee5fc8bf45235eeb7b0873ab6
parent 5635b7d1

media/extractors/mp4/MPEG4Extractor.cpp

+19 −11
Original line number Diff line number Diff line
@@ -81,7 +81,7 @@ public: 
                const Trex *trex,

                off64_t firstMoofOffset,

                const sp<ItemTable> &itemTable,

                int32_t elstShiftStartTicks);

                uint64_t elstShiftStartTicks);

    virtual status_t init();



    virtual media_status_t start();
@@ -147,7 +147,7 @@ private: 


    // Start offset from composition time to presentation time.

    // Support shift only for video tracks through mElstShiftStartTicks for now.

    int32_t mElstShiftStartTicks;

    uint64_t mElstShiftStartTicks;



    size_t parseNALSize(const uint8_t *data) const;

    status_t parseChunk(off64_t *offset);
@@ -4040,7 +4040,7 @@ MediaTrackHelper *MPEG4Extractor::getTrack(size_t index) { 


    if (track->has_elst and !strncasecmp("video/", mime, 6) and track->elst_media_time > 0) {

        track->elstShiftStartTicks = track->elst_media_time;

        ALOGV("video track->elstShiftStartTicks :%" PRId64, track->elst_media_time);

        ALOGV("video track->elstShiftStartTicks :%" PRIu64, track->elstShiftStartTicks);

    }



    MPEG4Source *source =  new MPEG4Source(
@@ -4450,7 +4450,7 @@ MPEG4Source::MPEG4Source( 
        const Trex *trex,

        off64_t firstMoofOffset,

        const sp<ItemTable> &itemTable,

        int32_t elstShiftStartTicks)

        uint64_t elstShiftStartTicks)

    : mFormat(format),

      mDataSource(dataSource),

      mTimescale(timeScale),
@@ -4576,7 +4576,7 @@ status_t MPEG4Source::init() { 
            // Start offset should be less or equal to composition time of first sample.

            // ISO : sample_composition_time_offset, version 0 (unsigned) for major brands.

            mElstShiftStartTicks = std::min(mElstShiftStartTicks,

                (*mCurrentSamples.begin()).compositionOffset);

                                            (uint64_t)(*mCurrentSamples.begin()).compositionOffset);

        }

        return err;

    }
@@ -4586,7 +4586,7 @@ status_t MPEG4Source::init() { 
        err = mSampleTable->getMetaDataForSample(0, NULL, NULL, &firstSampleCTS);

        // Start offset should be less or equal to composition time of first sample.

        // Composition time stamp of first sample cannot be negative.

        mElstShiftStartTicks = std::min(mElstShiftStartTicks, (int32_t)firstSampleCTS);

        mElstShiftStartTicks = std::min(mElstShiftStartTicks, firstSampleCTS);

    }



    return err;
@@ -5496,7 +5496,11 @@ media_status_t MPEG4Source::read( 
            err = mSampleTable->getMetaDataForSample(

                    mCurrentSampleIndex, &offset, &size, &cts, &isSyncSample, &stts);

            if(err == OK) {

                cts -= mElstShiftStartTicks;

                /* Composition Time Stamp cannot be negative. Some files have video Sample

                * Time(STTS)delta with zero value(b/117402420).  Hence subtract only

                * min(cts, mElstShiftStartTicks), so that audio tracks can be played.

                */

                cts -= std::min(cts, mElstShiftStartTicks);

            }



        } else {
@@ -5780,7 +5784,7 @@ media_status_t MPEG4Source::fragmentedRead( 
    if (options && options->getSeekTo(&seekTimeUs, &mode)) {



        seekTimeUs += ((long double)mElstShiftStartTicks * 1000000) / mTimescale;

        ALOGV("shifted seekTimeUs :%" PRId64 ", mElstShiftStartTicks:%" PRId32, seekTimeUs,

        ALOGV("shifted seekTimeUs :%" PRId64 ", mElstShiftStartTicks:%" PRIu64, seekTimeUs,

              mElstShiftStartTicks);



        int numSidxEntries = mSegments.size();
@@ -5837,7 +5841,7 @@ media_status_t MPEG4Source::fragmentedRead( 


    off64_t offset = 0;

    size_t size = 0;

    uint32_t cts = 0;

    uint64_t cts = 0;

    bool isSyncSample = false;

    bool newBuffer = false;

    if (mBuffer == NULL || mCurrentSampleIndex >= mCurrentSamples.size()) {
@@ -5869,7 +5873,11 @@ media_status_t MPEG4Source::fragmentedRead( 
        offset = smpl->offset;

        size = smpl->size;

        cts = mCurrentTime + smpl->compositionOffset;

        cts -= mElstShiftStartTicks;

        /* Composition Time Stamp cannot be negative. Some files have video Sample

        * Time(STTS)delta with zero value(b/117402420).  Hence subtract only

        * min(cts, mElstShiftStartTicks), so that audio tracks can be played.

        */

        cts -= std::min(cts, mElstShiftStartTicks);



        mCurrentTime += smpl->duration;

        isSyncSample = (mCurrentSampleIndex == 0);

media/extractors/mp4/MPEG4Extractor.h

+5 −1
Original line number Diff line number Diff line
@@ -83,9 +83,13 @@ private: 
        bool includes_expensive_metadata;

        bool skipTrack;

        bool has_elst;

        /* signed int, ISO Spec allows media_time = -1 for other use cases.

         * but we don't support empty edits for now.

         */

        int64_t elst_media_time;

        uint64_t elst_segment_duration;

        int32_t elstShiftStartTicks;

        // unsigned int, shift start offset only when media_time > 0.

        uint64_t elstShiftStartTicks;

        bool subsample_encryption;

    };