VideoWriter won't open for MJPG stream

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I am trying to follow this tutorial (https://ariandy1.wordpress.com/2013/0...) but with OpenCV 3.0. I have this code:

int codec = VideoWriter::fourcc('M','J','P','G');
cout << "Frame size: " << frame.cols << " " << frame.rows << endl;
cout << "Opening output stream..." << codec << "  " << outStream.open("out.mjpg", codec, 2, Size(frame.cols,frame.rows), true) << endl;

frame is a Mat that is captured from a webcam. Here is the output:

Frame size: 352 288
Opening output stream...1196444237  0

As you can see VideoWriter::open() returns false (couted as zero). Am I doing something wrong?