detect faces and eyes simultaneously with opencv

face_eye_detect.py

def objectTracker2(facePath, eyePath):
    
    faceCascade = cv2.CascadeClassifier(facePath)
    eyeCascade  = cv2.CascadeClassifier(eyePath)
    cv2.namedWindow("preview")
    vc = cv2.VideoCapture(0)
    
    while True: # try to get the first frame
        rval, frame = vc.read()
        # Capture frame-by-frame
        ret, frame = vc.read()
        
        #Convert frame to grayscale
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    
        faces = faceCascade.detectMultiScale(gray, scaleFactor=1.2, 
                                               minNeighbors=1, minSize=(40, 40), 
                                               flags=cv2.CASCADE_SCALE_IMAGE)
        # Draw a rectangle around the faces
        for (x, y, w, h) in faces:
            cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 0), 2)
            #select face as region of interest 
            roi_g =  gray[y:y+h,x:x+h]
            roi_c = frame[y:y+h,x:x+h]
            #within region of interest find eyes
            eyes = eyeCascade.detectMultiScale(roi_g)
            #for each eye
            for (ex,ey,ew,eh) in eyes:
                #draw retangle around eye
                cv2.rectangle(roi_c, (ex,ey),(ex+ew,ey+eh),(0,255,0),2)
                    
        cv2.imshow("preview", frame)
        rval, frame = vc.read()
        key = cv2.waitKey(20)
        if key == 27: # exit on ESC
            break

    vc.release()
    cv2.destroyWindow("preview")