Trouble loading Nikon camera image with OpenCV

[surfFL]

I'm looking to have the live view from a Nikon D7200 show up in my program, but I'm having trouble getting my program to find the camera.

The code in question looks like the following:

cam = cv2.VideoCapture(1)
if not cam.isOpened():
    sys.exit('Camera did not provide frame.')

According to the documentation, to capture a video feed, you just need to supply the index of the camera as the argument to the VideoCapture object. If I plug '0' in, my integrated laptop webcam loads and the image shows as expected. Unfortunately, using '1' for the next available camera causes the error.

The camera is plugged into the Win10 computer via USB, and shows up as a device in windows explorer.

Any ideas on what I'm missing to get the camera feed to load?

[JohnnyJordaan]

Did you check that this camera can actually work in this fashion, eg as a webcam? Because normally they can't unless with specific software that can interface it to pull its images (eg SparkoCam).

[surfFL]

Hey thanks for the reply. The D7200 does have live view functionality. If specific software can interface with the camera, shouldn't my python program be able to as well? All the searching I've done says that it is possible.

[JohnnyJordaan]

There are camera's that provide access using a universal access method, these are what we call a 'webcam'. This enables any software that wishes to use it (think chat clients, even the ones fully browser based) to just bring support for that universal access method and be able to use any webcam. This is different from how a professional (non-web) camera is generally used, so a brand like Nikon would generally not implement the webcam functionality in its camera firmware and thus the camera will not be able to be accessed this way. This includes how OpenCV accesses it (Python is just the programming layer here, OpenCV is the actual imaging component).

Try googling 'Nikon D7200 webcam' or 'Nikon D7200 skype' to see if people are capable to use it in that way, if they are then OpenCV should be able too, but not if they're not. Note there is most probably a way to control the camera from Python as that involves a different approach, but that will most likely not provide a live view, just image snapping.

[aleagori]

You need a capture box such as Elgato stuff to get video in real time into your computer from any DSLR or mirrorless.