videoio(test): test V4L frame size changing manual test

modules/videoio/test/test_camera.cpp

@@ -11,7 +11,7 @@
 
 namespace opencv_test { namespace {
 
-static void test_readFrames(/*const*/ VideoCapture& capture, const int N = 100)
+static void test_readFrames(/*const*/ VideoCapture& capture, const int N = 100, Mat* lastFrame = NULL)
 {
     Mat frame;
     int64 time0 = cv::getTickCount();
@@ -26,6 +26,7 @@ static void test_readFrames(/*const*/ VideoCapture& capture, const int N = 100)
     }
     int64 time1 = cv::getTickCount();
     printf("Processed %d frames on %.2f FPS\n", N, (N * cv::getTickFrequency()) / (time1 - time0 + 1));
+    if (lastFrame) *lastFrame = frame.clone();
 }
 
 TEST(DISABLED_VideoIO_Camera, basic)
@@ -55,4 +56,39 @@ TEST(DISABLED_VideoIO_Camera, validate_V4L2_MJPEG)
     capture.release();
 }
 
+TEST(DISABLED_VideoIO_Camera, validate_V4L2_FrameSize)
+{
+    VideoCapture capture(CAP_V4L2);
+    ASSERT_TRUE(capture.isOpened());
+    std::cout << "Camera 0 via " << capture.getBackendName() << " backend" << std::endl;
+    std::cout << "Frame width: " << capture.get(CAP_PROP_FRAME_WIDTH) << std::endl;
+    std::cout << "     height: " << capture.get(CAP_PROP_FRAME_HEIGHT) << std::endl;
+    std::cout << "Capturing FPS: " << capture.get(CAP_PROP_FPS) << std::endl;
+    int fourcc = (int)capture.get(CAP_PROP_FOURCC);
+    std::cout << "FOURCC code: " << cv::format("0x%8x", fourcc) << std::endl;
+    test_readFrames(capture, 30);
+
+    EXPECT_TRUE(capture.set(CAP_PROP_FRAME_WIDTH, 640));
+    EXPECT_TRUE(capture.set(CAP_PROP_FRAME_HEIGHT, 480));
+    std::cout << "Frame width: " << capture.get(CAP_PROP_FRAME_WIDTH) << std::endl;
+    std::cout << "     height: " << capture.get(CAP_PROP_FRAME_HEIGHT) << std::endl;
+    std::cout << "Capturing FPS: " << capture.get(CAP_PROP_FPS) << std::endl;
+    Mat frame640x480;
+    test_readFrames(capture, 30, &frame640x480);
+    EXPECT_EQ(640, frame640x480.cols);
+    EXPECT_EQ(480, frame640x480.rows);
+
+    EXPECT_TRUE(capture.set(CAP_PROP_FRAME_WIDTH, 1280));
+    EXPECT_TRUE(capture.set(CAP_PROP_FRAME_HEIGHT, 720));
+    std::cout << "Frame width: " << capture.get(CAP_PROP_FRAME_WIDTH) << std::endl;
+    std::cout << "     height: " << capture.get(CAP_PROP_FRAME_HEIGHT) << std::endl;
+    std::cout << "Capturing FPS: " << capture.get(CAP_PROP_FPS) << std::endl;
+    Mat frame1280x720;
+    test_readFrames(capture, 30, &frame1280x720);
+    EXPECT_EQ(1280, frame1280x720.cols);
+    EXPECT_EQ(720, frame1280x720.rows);
+
+    capture.release();
+}
+
 }} // namespace