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Commit dacebe62 authored by James Dong's avatar James Dong
Browse files

Fix track duration calculation if the start timestamp is non-zero 

o Updated the comments in the patch
o Added some additional checks on the timestamp

Change-Id: I8ad81eb6bfe358c1db5245cbb52efc905cdc234c
parent 6d8fae72

media/libstagefright/MPEG4Writer.cpp

+36 −3
Original line number Original line Diff line number Diff line
@@ -1541,20 +1541,52 @@ status_t MPEG4Writer::Track::threadEntry() { 
        int32_t isSync = false;

        int32_t isSync = false;

        meta_data->findInt32(kKeyIsSyncFrame, &isSync);

        meta_data->findInt32(kKeyIsSyncFrame, &isSync);





        /*

         * The original timestamp found in the data buffer will be modified as below:

         *

         * There is a playback offset into this track if the track's start time

         * is not the same as the movie start time, which will be recorded in edst

         * box of the output file. The playback offset is to make sure that the

         * starting time of the audio/video tracks are synchronized. Although the

         * track's media timestamp may be subject to various modifications

         * as outlined below, the track's playback offset time remains unchanged

         * once the first data buffer of the track is received.

         *

         * The media time stamp will be calculated by subtracting the playback offset

         * (and potential pause durations) from the original timestamp in the buffer.

         *

         * If this track is a video track for a real-time recording application with

         * both audio and video tracks, its media timestamp will subject to further

         * modification based on the media clock of the audio track. This modification

         * is needed for the purpose of maintaining good audio/video synchronization.

         *

         * If the recording session is paused and resumed multiple times, the track

         * media timestamp will be modified as if the  recording session had never been

         * paused at all during playback of the recorded output file. In other words,

         * the output file will have no memory of pause/resume durations.

         *

         */

        CHECK(meta_data->findInt64(kKeyTime, &timestampUs));

        CHECK(meta_data->findInt64(kKeyTime, &timestampUs));

        LOGV("%s timestampUs: %lld", mIsAudio? "Audio": "Video", timestampUs);





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

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

        if (mSampleSizes.empty()) {

        if (mSampleSizes.empty()) {

            mStartTimestampUs = timestampUs;

            mStartTimestampUs = timestampUs;

            mOwner->setStartTimestampUs(mStartTimestampUs);

            mOwner->setStartTimestampUs(mStartTimestampUs);

            previousPausedDurationUs = mStartTimestampUs;

        }

        }





        if (mResumed) {

        if (mResumed) {

            previousPausedDurationUs += (timestampUs - mTrackDurationUs - lastDurationUs);

            int64_t durExcludingEarlierPausesUs = timestampUs - previousPausedDurationUs;

            CHECK(durExcludingEarlierPausesUs >= 0);

            int64_t pausedDurationUs = durExcludingEarlierPausesUs - mTrackDurationUs;

            CHECK(pausedDurationUs >= lastDurationUs);

            previousPausedDurationUs += pausedDurationUs - lastDurationUs;

            mResumed = false;

            mResumed = false;

        }

        }





        timestampUs -= previousPausedDurationUs;

        timestampUs -= previousPausedDurationUs;

        CHECK(timestampUs >= 0);

        if (mIsRealTimeRecording && !mIsAudio) {

        if (mIsRealTimeRecording && !mIsAudio) {

            // The minor adjustment on the timestamp is heuristic/experimental

            // The minor adjustment on the timestamp is heuristic/experimental

            // We are adjusting the timestamp to reduce the fluctuation of the duration

            // We are adjusting the timestamp to reduce the fluctuation of the duration
@@ -1590,8 +1622,8 @@ status_t MPEG4Writer::Track::threadEntry() { 
            }

            }

        }

        }





        LOGV("time stamp: %lld and previous paused duration %lld",

        LOGV("%s media time stamp: %lld and previous paused duration %lld",

                timestampUs, previousPausedDurationUs);

                mIsAudio? "Audio": "Video", timestampUs, previousPausedDurationUs);

        if (timestampUs > mTrackDurationUs) {

        if (timestampUs > mTrackDurationUs) {

            mTrackDurationUs = timestampUs;

            mTrackDurationUs = timestampUs;

        }

        }
@@ -1873,6 +1905,7 @@ void MPEG4Writer::Track::writeTrackHeader( 




            // First elst entry: specify the starting time offset

            // First elst entry: specify the starting time offset

            int64_t offsetUs = mStartTimestampUs - moovStartTimeUs;

            int64_t offsetUs = mStartTimestampUs - moovStartTimeUs;

            LOGV("OffsetUs: %lld", offsetUs);

            int32_t seg = (offsetUs * mvhdTimeScale + 5E5) / 1E6;

            int32_t seg = (offsetUs * mvhdTimeScale + 5E5) / 1E6;

            mOwner->writeInt32(seg);         // in mvhd timecale

            mOwner->writeInt32(seg);         // in mvhd timecale

            mOwner->writeInt32(-1);          // starting time offset

            mOwner->writeInt32(-1);          // starting time offset