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#include "precomp.hpp"

using namespace cv;
using namespace cv::cuda;

#if !defined HAVE_CUDA || defined(CUDA_DISABLER)

Ptr<FarnebackOpticalFlow> cv::cuda::FarnebackOpticalFlow::create(int, double, bool, int, int, int, double, int) { throw_no_cuda(); return Ptr<FarnebackOpticalFlow>(); }

#else

#define MIN_SIZE 32

// CUDA resize() is fast, but it differs from the CPU analog. Disabling this flag
// leads to an inefficient code. It's for debug purposes only.
#define ENABLE_CUDA_RESIZE 1

namespace cv { namespace cuda { namespace device { namespace optflow_farneback
{
    void setPolynomialExpansionConsts(
            int polyN, const float *g, const float *xg, const float *xxg,
            float ig11, float ig03, float ig33, float ig55);

    void polynomialExpansionGpu(const PtrStepSzf &src, int polyN, PtrStepSzf dst, cudaStream_t stream);

    void setUpdateMatricesConsts();

    void updateMatricesGpu(
            const PtrStepSzf flowx, const PtrStepSzf flowy, const PtrStepSzf R0, const PtrStepSzf R1,
            PtrStepSzf M, cudaStream_t stream);

    void updateFlowGpu(
            const PtrStepSzf M, PtrStepSzf flowx, PtrStepSzf flowy, cudaStream_t stream);

    void boxFilter5Gpu(const PtrStepSzf src, int ksizeHalf, PtrStepSzf dst, cudaStream_t stream);

    void boxFilter5Gpu_CC11(const PtrStepSzf src, int ksizeHalf, PtrStepSzf dst, cudaStream_t stream);

    void setGaussianBlurKernel(const float *gKer, int ksizeHalf);

    void gaussianBlurGpu(
            const PtrStepSzf src, int ksizeHalf, PtrStepSzf dst, int borderType, cudaStream_t stream);

    void gaussianBlur5Gpu(
            const PtrStepSzf src, int ksizeHalf, PtrStepSzf dst, int borderType, cudaStream_t stream);

    void gaussianBlur5Gpu_CC11(
            const PtrStepSzf src, int ksizeHalf, PtrStepSzf dst, int borderType, cudaStream_t stream);

}}}}

namespace
{
    class FarnebackOpticalFlowImpl : public FarnebackOpticalFlow
    {
    public:
        FarnebackOpticalFlowImpl(int numLevels, double pyrScale, bool fastPyramids, int winSize,
                                 int numIters, int polyN, double polySigma, int flags) :
            numLevels_(numLevels), pyrScale_(pyrScale), fastPyramids_(fastPyramids), winSize_(winSize),
            numIters_(numIters), polyN_(polyN), polySigma_(polySigma), flags_(flags)
        {
        }

        virtual int getNumLevels() const { return numLevels_; }
        virtual void setNumLevels(int numLevels) { numLevels_ = numLevels; }

        virtual double getPyrScale() const { return pyrScale_; }
        virtual void setPyrScale(double pyrScale) { pyrScale_ = pyrScale; }

        virtual bool getFastPyramids() const { return fastPyramids_; }
        virtual void setFastPyramids(bool fastPyramids) { fastPyramids_ = fastPyramids; }

        virtual int getWinSize() const { return winSize_; }
        virtual void setWinSize(int winSize) { winSize_ = winSize; }

        virtual int getNumIters() const { return numIters_; }
        virtual void setNumIters(int numIters) { numIters_ = numIters; }

        virtual int getPolyN() const { return polyN_; }
        virtual void setPolyN(int polyN) { polyN_ = polyN; }

        virtual double getPolySigma() const { return polySigma_; }
        virtual void setPolySigma(double polySigma) { polySigma_ = polySigma; }

        virtual int getFlags() const { return flags_; }
        virtual void setFlags(int flags) { flags_ = flags; }

        virtual void calc(InputArray I0, InputArray I1, InputOutputArray flow, Stream& stream);

    private:
        int numLevels_;
        double pyrScale_;
        bool fastPyramids_;
        int winSize_;
        int numIters_;
        int polyN_;
        double polySigma_;
        int flags_;

    private:
        void prepareGaussian(
                int n, double sigma, float *g, float *xg, float *xxg,
                double &ig11, double &ig03, double &ig33, double &ig55);

        void setPolynomialExpansionConsts(int n, double sigma);

        void updateFlow_boxFilter(
                const GpuMat& R0, const GpuMat& R1, GpuMat& flowx, GpuMat &flowy,
                GpuMat& M, GpuMat &bufM, int blockSize, bool updateMatrices, Stream streams[]);

        void updateFlow_gaussianBlur(
                const GpuMat& R0, const GpuMat& R1, GpuMat& flowx, GpuMat& flowy,
                GpuMat& M, GpuMat &bufM, int blockSize, bool updateMatrices, Stream streams[]);

        void calcImpl(const GpuMat &frame0, const GpuMat &frame1, GpuMat &flowx, GpuMat &flowy, Stream &stream);

        GpuMat frames_[2];
        GpuMat pyrLevel_[2], M_, bufM_, R_[2], blurredFrame_[2];
        std::vector<GpuMat> pyramid0_, pyramid1_;
    };

    void FarnebackOpticalFlowImpl::calc(InputArray _frame0, InputArray _frame1, InputOutputArray _flow, Stream& stream)
    {
        const GpuMat frame0 = _frame0.getGpuMat();
        const GpuMat frame1 = _frame1.getGpuMat();

        BufferPool pool(stream);
        GpuMat flowx = pool.getBuffer(frame0.size(), CV_32FC1);
        GpuMat flowy = pool.getBuffer(frame0.size(), CV_32FC1);

        calcImpl(frame0, frame1, flowx, flowy, stream);

        GpuMat flows[] = {flowx, flowy};
        cuda::merge(flows, 2, _flow, stream);
    }

    GpuMat allocMatFromBuf(int rows, int cols, int type, GpuMat& mat)
    {
        if (!mat.empty() && mat.type() == type && mat.rows >= rows && mat.cols >= cols)
            return mat(Rect(0, 0, cols, rows));

        return mat = GpuMat(rows, cols, type);
    }

    void FarnebackOpticalFlowImpl::prepareGaussian(
            int n, double sigma, float *g, float *xg, float *xxg,
            double &ig11, double &ig03, double &ig33, double &ig55)
    {
        double s = 0.;
        for (int x = -n; x <= n; x++)
        {
            g[x] = (float)std::exp(-x*x/(2*sigma*sigma));
            s += g[x];
        }

        s = 1./s;
        for (int x = -n; x <= n; x++)
        {
            g[x] = (float)(g[x]*s);
            xg[x] = (float)(x*g[x]);
            xxg[x] = (float)(x*x*g[x]);
        }

        Mat_<double> G(6, 6);
        G.setTo(0);

        for (int y = -n; y <= n; y++)
        {
            for (int x = -n; x <= n; x++)
            {
                G(0,0) += g[y]*g[x];
                G(1,1) += g[y]*g[x]*x*x;
                G(3,3) += g[y]*g[x]*x*x*x*x;
                G(5,5) += g[y]*g[x]*x*x*y*y;
            }
        }

        //G[0][0] = 1.;
        G(2,2) = G(0,3) = G(0,4) = G(3,0) = G(4,0) = G(1,1);
        G(4,4) = G(3,3);
        G(3,4) = G(4,3) = G(5,5);

        // invG:
        // [ x        e  e    ]
        // [    y             ]
        // [       y          ]
        // [ e        z       ]
        // [ e           z    ]
        // [                u ]
        Mat_<double> invG = G.inv(DECOMP_CHOLESKY);

        ig11 = invG(1,1);
        ig03 = invG(0,3);
        ig33 = invG(3,3);
        ig55 = invG(5,5);
    }

    void FarnebackOpticalFlowImpl::setPolynomialExpansionConsts(int n, double sigma)
    {
        std::vector<float> buf(n*6 + 3);
        float* g = &buf[0] + n;
        float* xg = g + n*2 + 1;
        float* xxg = xg + n*2 + 1;

        if (sigma < FLT_EPSILON)
            sigma = n*0.3;

        double ig11, ig03, ig33, ig55;
        prepareGaussian(n, sigma, g, xg, xxg, ig11, ig03, ig33, ig55);

        device::optflow_farneback::setPolynomialExpansionConsts(n, g, xg, xxg, static_cast<float>(ig11), static_cast<float>(ig03), static_cast<float>(ig33), static_cast<float>(ig55));
    }

    void FarnebackOpticalFlowImpl::updateFlow_boxFilter(
            const GpuMat& R0, const GpuMat& R1, GpuMat& flowx, GpuMat &flowy,
            GpuMat& M, GpuMat &bufM, int blockSize, bool updateMatrices, Stream streams[])
    {
        if (deviceSupports(FEATURE_SET_COMPUTE_12))
            device::optflow_farneback::boxFilter5Gpu(M, blockSize/2, bufM, StreamAccessor::getStream(streams[0]));
        else
            device::optflow_farneback::boxFilter5Gpu_CC11(M, blockSize/2, bufM, StreamAccessor::getStream(streams[0]));
        swap(M, bufM);

        for (int i = 1; i < 5; ++i)
            streams[i].waitForCompletion();
        device::optflow_farneback::updateFlowGpu(M, flowx, flowy, StreamAccessor::getStream(streams[0]));

        if (updateMatrices)
            device::optflow_farneback::updateMatricesGpu(flowx, flowy, R0, R1, M, StreamAccessor::getStream(streams[0]));
    }

    void FarnebackOpticalFlowImpl::updateFlow_gaussianBlur(
            const GpuMat& R0, const GpuMat& R1, GpuMat& flowx, GpuMat& flowy,
            GpuMat& M, GpuMat &bufM, int blockSize, bool updateMatrices, Stream streams[])
    {
        if (deviceSupports(FEATURE_SET_COMPUTE_12))
            device::optflow_farneback::gaussianBlur5Gpu(
                        M, blockSize/2, bufM, BORDER_REPLICATE, StreamAccessor::getStream(streams[0]));
        else
            device::optflow_farneback::gaussianBlur5Gpu_CC11(
                        M, blockSize/2, bufM, BORDER_REPLICATE, StreamAccessor::getStream(streams[0]));
        swap(M, bufM);

        device::optflow_farneback::updateFlowGpu(M, flowx, flowy, StreamAccessor::getStream(streams[0]));

        if (updateMatrices)
            device::optflow_farneback::updateMatricesGpu(flowx, flowy, R0, R1, M, StreamAccessor::getStream(streams[0]));
    }

    void FarnebackOpticalFlowImpl::calcImpl(const GpuMat &frame0, const GpuMat &frame1, GpuMat &flowx, GpuMat &flowy, Stream &stream)
    {
        CV_Assert(frame0.channels() == 1 && frame1.channels() == 1);
        CV_Assert(frame0.size() == frame1.size());
        CV_Assert(polyN_ == 5 || polyN_ == 7);
        CV_Assert(!fastPyramids_ || std::abs(pyrScale_ - 0.5) < 1e-6);

        Stream streams[5];
        if (stream)
            streams[0] = stream;

        Size size = frame0.size();
        GpuMat prevFlowX, prevFlowY, curFlowX, curFlowY;

        flowx.create(size, CV_32F);
        flowy.create(size, CV_32F);
        GpuMat flowx0 = flowx;
        GpuMat flowy0 = flowy;

        // Crop unnecessary levels
        double scale = 1;
        int numLevelsCropped = 0;
        for (; numLevelsCropped < numLevels_; numLevelsCropped++)
        {
            scale *= pyrScale_;
            if (size.width*scale < MIN_SIZE || size.height*scale < MIN_SIZE)
                break;
        }

        frame0.convertTo(frames_[0], CV_32F, streams[0]);
        frame1.convertTo(frames_[1], CV_32F, streams[1]);

        if (fastPyramids_)
        {
            // Build Gaussian pyramids using pyrDown()
            pyramid0_.resize(numLevelsCropped + 1);
            pyramid1_.resize(numLevelsCropped + 1);
            pyramid0_[0] = frames_[0];
            pyramid1_[0] = frames_[1];
            for (int i = 1; i <= numLevelsCropped; ++i)
            {
                cuda::pyrDown(pyramid0_[i - 1], pyramid0_[i], streams[0]);
                cuda::pyrDown(pyramid1_[i - 1], pyramid1_[i], streams[1]);
            }
        }

        setPolynomialExpansionConsts(polyN_, polySigma_);
        device::optflow_farneback::setUpdateMatricesConsts();

        for (int k = numLevelsCropped; k >= 0; k--)
        {
            streams[0].waitForCompletion();

            scale = 1;
            for (int i = 0; i < k; i++)
                scale *= pyrScale_;

            double sigma = (1./scale - 1) * 0.5;
            int smoothSize = cvRound(sigma*5) | 1;
            smoothSize = std::max(smoothSize, 3);

            int width = cvRound(size.width*scale);
            int height = cvRound(size.height*scale);

            if (fastPyramids_)
            {
                width = pyramid0_[k].cols;
                height = pyramid0_[k].rows;
            }

            if (k > 0)
            {
                curFlowX.create(height, width, CV_32F);
                curFlowY.create(height, width, CV_32F);
            }
            else
            {
                curFlowX = flowx0;
                curFlowY = flowy0;
            }

            if (!prevFlowX.data)
            {
                if (flags_ & OPTFLOW_USE_INITIAL_FLOW)
                {
                    cuda::resize(flowx0, curFlowX, Size(width, height), 0, 0, INTER_LINEAR, streams[0]);
                    cuda::resize(flowy0, curFlowY, Size(width, height), 0, 0, INTER_LINEAR, streams[1]);
                    curFlowX.convertTo(curFlowX, curFlowX.depth(), scale, streams[0]);
                    curFlowY.convertTo(curFlowY, curFlowY.depth(), scale, streams[1]);
                }
                else
                {
                    curFlowX.setTo(0, streams[0]);
                    curFlowY.setTo(0, streams[1]);
                }
            }
            else
            {
                cuda::resize(prevFlowX, curFlowX, Size(width, height), 0, 0, INTER_LINEAR, streams[0]);
                cuda::resize(prevFlowY, curFlowY, Size(width, height), 0, 0, INTER_LINEAR, streams[1]);
                curFlowX.convertTo(curFlowX, curFlowX.depth(), 1./pyrScale_, streams[0]);
                curFlowY.convertTo(curFlowY, curFlowY.depth(), 1./pyrScale_, streams[1]);
            }

            GpuMat M = allocMatFromBuf(5*height, width, CV_32F, M_);
            GpuMat bufM = allocMatFromBuf(5*height, width, CV_32F, bufM_);
            GpuMat R[2] =
            {
                allocMatFromBuf(5*height, width, CV_32F, R_[0]),
                allocMatFromBuf(5*height, width, CV_32F, R_[1])
            };

            if (fastPyramids_)
            {
                device::optflow_farneback::polynomialExpansionGpu(pyramid0_[k], polyN_, R[0], StreamAccessor::getStream(streams[0]));
                device::optflow_farneback::polynomialExpansionGpu(pyramid1_[k], polyN_, R[1], StreamAccessor::getStream(streams[1]));
            }
            else
            {
                GpuMat blurredFrame[2] =
                {
                    allocMatFromBuf(size.height, size.width, CV_32F, blurredFrame_[0]),
                    allocMatFromBuf(size.height, size.width, CV_32F, blurredFrame_[1])
                };
                GpuMat pyrLevel[2] =
                {
                    allocMatFromBuf(height, width, CV_32F, pyrLevel_[0]),
                    allocMatFromBuf(height, width, CV_32F, pyrLevel_[1])
                };

                Mat g = getGaussianKernel(smoothSize, sigma, CV_32F);
                device::optflow_farneback::setGaussianBlurKernel(g.ptr<float>(smoothSize/2), smoothSize/2);

                for (int i = 0; i < 2; i++)
                {
                    device::optflow_farneback::gaussianBlurGpu(
                            frames_[i], smoothSize/2, blurredFrame[i], BORDER_REFLECT101, StreamAccessor::getStream(streams[i]));
                    cuda::resize(blurredFrame[i], pyrLevel[i], Size(width, height), 0.0, 0.0, INTER_LINEAR, streams[i]);
                    device::optflow_farneback::polynomialExpansionGpu(pyrLevel[i], polyN_, R[i], StreamAccessor::getStream(streams[i]));
                }
            }

            streams[1].waitForCompletion();
            device::optflow_farneback::updateMatricesGpu(curFlowX, curFlowY, R[0], R[1], M, StreamAccessor::getStream(streams[0]));

            if (flags_ & OPTFLOW_FARNEBACK_GAUSSIAN)
            {
                Mat g = getGaussianKernel(winSize_, winSize_/2*0.3f, CV_32F);
                device::optflow_farneback::setGaussianBlurKernel(g.ptr<float>(winSize_/2), winSize_/2);
            }
            for (int i = 0; i < numIters_; i++)
            {
                if (flags_ & OPTFLOW_FARNEBACK_GAUSSIAN)
                    updateFlow_gaussianBlur(R[0], R[1], curFlowX, curFlowY, M, bufM, winSize_, i < numIters_-1, streams);
                else
                    updateFlow_boxFilter(R[0], R[1], curFlowX, curFlowY, M, bufM, winSize_, i < numIters_-1, streams);
            }

            prevFlowX = curFlowX;
            prevFlowY = curFlowY;
        }

        flowx = curFlowX;
        flowy = curFlowY;

        if (!stream)
            streams[0].waitForCompletion();
    }
}

Ptr<FarnebackOpticalFlow> cv::cuda::FarnebackOpticalFlow::create(int numLevels, double pyrScale, bool fastPyramids, int winSize,
                                                                 int numIters, int polyN, double polySigma, int flags)
{
    return makePtr<FarnebackOpticalFlowImpl>(numLevels, pyrScale, fastPyramids, winSize,
                                             numIters, polyN, polySigma, flags);
}

#endif
