chore: import upstream snapshot with attribution

samples/gpu/video_reader.cpp

@@ -0,0 +1,71 @@
+#include <iostream>
+
+#include "opencv2/opencv_modules.hpp"
+
+#if defined(HAVE_OPENCV_CUDACODEC)
+
+#include <string>
+#include <vector>
+#include <algorithm>
+#include <numeric>
+
+#include <opencv2/core.hpp>
+#include <opencv2/core/opengl.hpp>
+#include <opencv2/cudacodec.hpp>
+#include <opencv2/highgui.hpp>
+
+int main(int argc, const char* argv[])
+{
+    if (argc != 2)
+        return -1;
+
+    const std::string fname(argv[1]);
+
+    cv::namedWindow("CPU", cv::WINDOW_NORMAL);
+#if defined(HAVE_OPENGL)
+    cv::namedWindow("GPU", cv::WINDOW_OPENGL);
+    cv::cuda::setGlDevice();
+#else
+    cv::namedWindow("GPU", cv::WINDOW_NORMAL);
+#endif
+
+    cv::TickMeter tm;
+    cv::Mat frame;
+    cv::VideoCapture reader(fname);
+    for (;;)
+    {
+        if (!reader.read(frame))
+            break;
+        cv::imshow("CPU", frame);
+        if (cv::waitKey(3) > 0)
+            break;
+    }
+
+    cv::cuda::GpuMat d_frame;
+    cv::Ptr<cv::cudacodec::VideoReader> d_reader = cv::cudacodec::createVideoReader(fname);
+    for (;;)
+    {
+        if (!d_reader->nextFrame(d_frame))
+            break;
+#if defined(HAVE_OPENGL)
+        cv::imshow("GPU", cv::ogl::Texture2D(d_frame));
+#else
+        d_frame.download(frame);
+        cv::imshow("GPU", frame);
+#endif
+        if (cv::waitKey(3) > 0)
+            break;
+    }
+
+    return 0;
+}
+
+#else
+
+int main()
+{
+    std::cout << "OpenCV was built without CUDA Video decoding support\n" << std::endl;
+    return 0;
+}
+
+#endif