def frame_corners(w, h, corners: dict = {}):
    """Returns a dictionary with the corner positions of the video frame

    Parameters:
        - w (int): width of the frame in pixels
        - h (int): height of the frame in pixels
        - corners (dict): dictionary containing corners to overwrite

    Returns:
        - defaults (dict): dictionary with overwriten parameters. Those not
        specified in the input retain their default values"""

    defaults = {
        "downleft": (int(w * 0.3 / 10), int(h / 1.05)),
        "downright": (int(w * 6.5 / 10), int(h / 1.05)),
        "upleft": (int(w * 0.3 / 10), int(h / 20)),
        "upright": (int(w * 6.3 / 10), int(h / 20)),
    }

    for k, v in corners.items():
        defaults[k] = v

    return defaults