VideoWriter creates video with 600 FPS.

I'm using opencv2. I'm initializing VideoWriter in the following manner:

VideoWriter video("outcpp.avi", CV_FOURCC('M', 'J', 'P', 'G'), FPS, Size(frame_width, frame_height));

where FPS = 20.0.

I am creating each frame with code and writting it with:

video << colorFrame;

When I open the output with mplayer, or when I use double fps = cap.get(CV_CAP_PROP_FPS);, I always get 600.0 fps.

Is there something I'm missing here?

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