Merge remote-tracking branch 'upstream/3.4' into merge-3.4

modules/videoio/test/test_ffmpeg.cpp

@@ -180,6 +180,54 @@ const videoio_container_params_t videoio_container_params[] =
 
 INSTANTIATE_TEST_CASE_P(/**/, videoio_container, testing::ValuesIn(videoio_container_params));
 
+typedef tuple<string, string, int> videoio_skip_params_t;
+typedef testing::TestWithParam< videoio_skip_params_t > videoio_skip;
+
+TEST_P(videoio_skip, DISABLED_read)  // optional test, may fail in some configurations
+{
+#if CV_VERSION_MAJOR >= 4
+    if (!videoio_registry::hasBackend(CAP_FFMPEG))
+        throw SkipTestException("Backend was not found");
+#endif
+
+    const string path = get<0>(GetParam());
+    const string env = get<1>(GetParam());
+    const int expectedFrameNumber = get<2>(GetParam());
+
+    #ifdef _WIN32
+        _putenv_s("OPENCV_FFMPEG_CAPTURE_OPTIONS", env.c_str());
+    #else
+        setenv("OPENCV_FFMPEG_CAPTURE_OPTIONS", env.c_str(), 1);
+    #endif
+    VideoCapture container(findDataFile(path), CAP_FFMPEG);
+    #ifdef _WIN32
+        _putenv_s("OPENCV_FFMPEG_CAPTURE_OPTIONS", "");
+    #else
+        setenv("OPENCV_FFMPEG_CAPTURE_OPTIONS", "", 1);
+    #endif
+
+    ASSERT_TRUE(container.isOpened());
+
+    Mat reference;
+    int nframes = 0, n_err = 0;
+    while (container.isOpened())
+    {
+        if (container.read(reference))
+            nframes++;
+        else if (++n_err > 3)
+            break;
+    }
+    EXPECT_EQ(expectedFrameNumber, nframes);
+}
+
+const videoio_skip_params_t videoio_skip_params[] =
+{
+    videoio_skip_params_t("video/big_buck_bunny.mp4", "", 125),
+    videoio_skip_params_t("video/big_buck_bunny.mp4", "avdiscard;nonkey", 11)
+};
+
+INSTANTIATE_TEST_CASE_P(/**/, videoio_skip, testing::ValuesIn(videoio_skip_params));
+
 //==========================================================================
 
 static void generateFrame(Mat &frame, unsigned int i, const Point &center, const Scalar &color)