Template matching with video input

Python
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1

I have a pretty basic template match function that takes a global variable, “path”, as input.

def operation(self):
    searchIn = cv2.imread(path, cv2.IMREAD_UNCHANGED)
    searchFor = cv2.imread('needle.png', cv2.IMREAD_UNCHANGED)

    result = cv2.matchTemplate(searchIn, searchFor, cv2.TM_CCOEFF_NORMED)

    cv2.imshow('Result', result)
    cv2.waitKey()
    cv2.destroyAllWindows()

    min_val, max_val, min_loc, max_loc = cv2.minMaxLoc(result)

    print(max_loc)

    print(max_val)

    if max_val > 0.9:
        print("Found it")

However, I want this function to take video input instead of just an image and I’m struggling with the implementation. I have tried something but keep getting an error message (see end of post for details). I don’t really know what I’m doing so if anyone could link me to some resources or explain how to do this, it would be really appreciated!

def operation(self):
        cap = cv2.VideoCapture(path)
        searchFor = cv2.imread('sampleIMG1.png', cv2.IMREAD_UNCHANGED)

        while cap.isOpened():
            ret, frame = cap.read()

            if not ret:
                print("Can't receive frame (stream end?). Exiting ...")
                break

            result = cv2.matchTemplate(cap, searchFor, cv2.TM_CCOEFF_NORMED)
            
            min_val, max_val, min_loc, max_loc = cv2.minMaxLoc(result)
            
            print(max_loc)
            print(max_val)
            if max_val > 0.9:
                print("Found it")

            if cv.waitKey(1) == ord('q'):
                break
            
        cap.release()
        cv.destroyAllWindows()

Here is the error message which I get:

  File "main.py", line 75, in operation
    result = cv2.matchTemplate(cap, searchFor, cv2.TM_CCOEFF_NORMED)
cv2.error: OpenCV(4.5.3) :-1: error: (-5:Bad argument) in function 'matchTemplate'
> Overload resolution failed:
>  - image is not a numpy array, neither a scalar
>  - Expected Ptr<cv::UMat> for argument 'image'