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Commit b540e0e7 authored by Yanqiang Fan's avatar Yanqiang Fan Committed by Dichen Zhang
Browse files

Fix rounding error accumulation of audio timestamp 

The calculating method of audio timestamp would cause rounding error
accumulated with a long time recording, as each current timestamp is
calculated with the previous timestamp.
This patch changes to calculate all timestamps on the basis of the
first frame to avoid accumulation of rounding error.

Bug: 128277968
Test: CTS - MediaRecorderTest
 ANDROID_BUILD_droid-cts/tools/cts-tradefed run cts -m
 CtsMediaTestCases --test android.media.cts.MediaRecorderTest

Change-Id: I3464d62c30e7b1fd0976419b845e6b9067f44615
parent 5e195df5

media/libstagefright/AudioSource.cpp

+5 −7
Original line number Diff line number Diff line
@@ -427,19 +427,17 @@ status_t AudioSource::dataCallback(const AudioRecord::Buffer& audioBuffer) { 
void AudioSource::queueInputBuffer_l(MediaBuffer *buffer, int64_t timeUs) {

    const size_t bufferSize = buffer->range_length();

    const size_t frameSize = mRecord->frameSize();

    const int64_t timestampUs =

                mPrevSampleTimeUs +

                    ((1000000LL * (bufferSize / frameSize)) +

                        (mSampleRate >> 1)) / mSampleRate;



    if (mNumFramesReceived == 0) {

        buffer->meta_data().setInt64(kKeyAnchorTime, mStartTimeUs);

    }



    mNumFramesReceived += bufferSize / frameSize;

    const int64_t timestampUs =

                mStartTimeUs +

                    ((1000000LL * mNumFramesReceived) +

                        (mSampleRate >> 1)) / mSampleRate;

    buffer->meta_data().setInt64(kKeyTime, mPrevSampleTimeUs);

    buffer->meta_data().setInt64(kKeyDriftTime, timeUs - mInitialReadTimeUs);

    mPrevSampleTimeUs = timestampUs;

    mNumFramesReceived += bufferSize / frameSize;

    mBuffersReceived.push_back(buffer);

    mFrameAvailableCondition.signal();

}