Merge pull request #3322 from StevenPuttemans:fix_pvpapi_interface

samples/cpp/videocapture_pvapi.cpp

+//////////////////////////////////////////////////////
+// Sample illustrating the use of the VideoCapture  //
+// interface in combination with PvAPI interface    //
+//                                                  //
+// Succesfully tested on Prosilica and Manta series //
+//////////////////////////////////////////////////////
+
+#include <iostream>
+#include "opencv2/opencv.hpp"
+
+using namespace std;
+using namespace cv;
+
+int main()
+{
+    // Capturing multiple AVT cameras can be done by simply initiating
+    // two VideoCaptures after eachother.
+    VideoCapture camera1(0 + CV_CAP_PVAPI);
+    VideoCapture camera2(0 + CV_CAP_PVAPI);
+    Mat frame1, frame2;
+
+    for(;;){
+        camera1 >> frame1;
+        camera2 >> frame2;
+
+        imshow("camera 1 frame", frame1);
+        imshow("camera 2 frame", frame2);
+
+        int key = waitKey(10);
+        if(key == 27){
+            break;
+        }
+    }
+
+    return 0;
+}