I’m not sure what you mean by “automatic” – if mean that is what it reported by PiVideo, it only refers to the input port being selected. Please refer to our documentation for additional information: PiCapture Documentation
You will always get “Raspberry Pi camera port is not active” with raspistill, because it does not keep the camera port operating unless it is actually capturing data. It doesn’t mean anything about the port readiness. If you run PiVideo while raspivid is running, or while the preview is active, you will see that it is in use then.
The OpenCV error seems to be a configuration problem, and again I suggest getting things working with raspivid first.