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Commit d2071871 authored by Lajos Molnar's avatar Lajos Molnar Committed by Hsiaoan Hsu
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stagefright: rtsp: handle overflow in jitter calculation 

Handle scenario when base jitter is fully 32-bit long.

Bug: 301990510
Test: Video long call / VT generic test
Change-Id: Ic0a4807885429da5354f0b3fc83c6198a20d9c44
Merged-In: Ic0a4807885429da5354f0b3fc83c6198a20d9c44
parent b30345a6

media/libstagefright/rtsp/JitterCalculator.cpp

+8 −1
Original line number Diff line number Diff line
@@ -47,7 +47,14 @@ void JitterCalc::putBaseData(uint32_t rtpTime, int64_t arrivalTimeUs) { 
    int64_t scheduledTimeUs = ((int32_t)diff) * 1000000ll / mClockRate;

    int64_t elapsedTimeUs = arrivalTimeUs - mFirstArrivalTimeUs;

    int64_t correctionTimeUs = elapsedTimeUs - scheduledTimeUs; // additional propagation delay;

    mBaseJitterUs = (mBaseJitterUs * 15 + correctionTimeUs) / 16;



    // We want to approximate correctionTimeUs by slowly (1:15) averaging into jitter base, but

    // both correction time and base jitter can roll over. Adjust correctionTime to be close to

    // base jitter. Accomplish this by calculating the closest 32-bit delta (positive or

    // negative) and applying 1/16th of it to the base jitter.

    int32_t correctionDiff;

    (void)__builtin_sub_overflow(correctionTimeUs, mBaseJitterUs, &correctionDiff);

    mBaseJitterUs = int32_t(int64_t(mBaseJitterUs) + correctionDiff / 16);

    ALOGV("BaseJitterUs : %lld \t\t correctionTimeUs : %lld",

            (long long)mBaseJitterUs, (long long)correctionTimeUs);

}