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Commit 4082162f authored by Pawin Vongmasa's avatar Pawin Vongmasa
Browse files

Relax the condition for dropping frames 

This CL lowers the threshold for rounding up the frame timestamp from
0.5 frames to 0.45 frames.

Test: Record 240fps video with Google Camera and use framedrop.py to
analyze the file.

Bug: 68953930
Change-Id: Ibe739528a7363c5f2576bfdf658a101b95bf15f1
parent 25a0160e

media/libstagefright/omx/GraphicBufferSource.cpp

+36 −4
Original line number Diff line number Diff line
@@ -46,6 +46,36 @@ 


namespace android {



namespace {

// kTimestampFluctuation is an upper bound of timestamp fluctuation from the

// source that GraphicBufferSource allows. The unit of kTimestampFluctuation is

// frames. More specifically, GraphicBufferSource will drop a frame if

//

// expectedNewFrametimestamp - actualNewFrameTimestamp <

//     (0.5 - kTimestampFluctuation) * expectedtimePeriodBetweenFrames

//

// where

// - expectedNewFrameTimestamp is the calculated ideal timestamp of the new

//   incoming frame

// - actualNewFrameTimestamp is the timestamp received from the source

// - expectedTimePeriodBetweenFrames is the ideal difference of the timestamps

//   of two adjacent frames

//

// See GraphicBufferSource::calculateCodecTimestamp_l() for more detail about

// how kTimestampFluctuation is used.

//

// kTimestampFluctuation should be non-negative. A higher value causes a smaller

// chance of dropping frames, but at the same time a higher bound on the

// difference between the source timestamp and the interpreted (snapped)

// timestamp.

//

// The value of 0.05 means that GraphicBufferSource expects the input timestamps

// to fluctuate no more than 5% from the regular time period.

//

// TODO: Justify the choice of this value, or make it configurable.

constexpr double kTimestampFluctuation = 0.05;

}



/**

 * A copiable object managing a buffer in the buffer cache managed by the producer. This object

 * holds a reference to the buffer, and maintains which buffer slot it belongs to (if any), and
@@ -732,14 +762,16 @@ bool GraphicBufferSource::calculateCodecTimestamp_l( 
            mFrameCount = 0;

        } else {

            // snap to nearest capture point

            int64_t nFrames = std::llround(

                    (timeUs - mPrevCaptureUs) * mCaptureFps / 1000000);

            if (nFrames <= 0) {

            double nFrames = (timeUs - mPrevCaptureUs) * mCaptureFps / 1000000;

            if (nFrames < 0.5 - kTimestampFluctuation) {

                // skip this frame as it's too close to previous capture

                ALOGV("skipping frame, timeUs %lld", static_cast<long long>(timeUs));

                return false;

            }

            mFrameCount += nFrames;

            if (nFrames <= 1.0) {

                nFrames = 1.0;

            }

            mFrameCount += std::llround(nFrames);

            mPrevCaptureUs = mBaseCaptureUs + std::llround(

                    mFrameCount * 1000000 / mCaptureFps);

            mPrevFrameUs = mBaseFrameUs + std::llround(