Merge "Revise capture interval calculation in StagefrightRecorder" into oc-dev

status_t StagefrightRecorder::setParamCaptureFps(double fps) {

    ALOGV("setParamCaptureFps: %.2f", fps);

    constexpr int64_t k1E12 = 1000000000000ll;

    int64_t fpsx1e12 = k1E12 * fps;

    if (fpsx1e12 == 0) {

        ALOGE("FPS is zero or too small");

        return BAD_VALUE;

    }

    // This does not overflow since 10^6 * 10^12 < 2^63

    int64_t timeUs = 1000000ll * k1E12 / fpsx1e12;

    // Not allowing time more than a day and a millisecond for error margin.

    // Note: 1e12 / 86400 = 11574074.(074) and 1e18 / 11574074 = 86400000553;

    //       therefore 1 ms of margin should be sufficient.

    if (timeUs <= 0 || timeUs > 86400001000ll) {

        ALOGE("Time between frame capture (%lld) is out of range [0, 1 Day]", (long long)timeUs);

    // FPS value is from Java layer where double follows IEEE-754, which is not

    // necessarily true for double here.

    constexpr double kIeee754Epsilon = 2.220446049250313e-16;

    constexpr double kEpsilon = std::max(std::numeric_limits<double>::epsilon(), kIeee754Epsilon);

    // Not allowing fps less than 1 frame / day minus epsilon.

    if (fps < 1.0 / 86400 - kEpsilon) {

        ALOGE("fps (%lf) is out of range (>= 1 frame / day)", fps);

        return BAD_VALUE;

    }

    mCaptureFps = fps;

    mTimeBetweenCaptureUs = timeUs;

    mTimeBetweenCaptureUs = std::llround(1e6 / fps);

    return OK;

}