def _get_framerate_delta(self):
    self._check_camera_open()
    if (self.framerate == 0):
        raise PiCameraValueError('framerate_delta cannot be used with framerate_range')
    port_num = (self.CAMERA_VIDEO_PORT if self._encoders else self.CAMERA_PREVIEW_PORT)
    return (self._camera.outputs[port_num].params[mmal.MMAL_PARAMETER_FRAME_RATE] - self.framerate)
def _get_framerate_delta(self):
    self._check_camera_open()
    if (self.framerate == 0):
        raise PiCameraValueError('framerate_delta cannot be used with framerate_range')
    port_num = (self.CAMERA_VIDEO_PORT if self._encoders else self.CAMERA_PREVIEW_PORT)
    return (self._camera.outputs[port_num].params[mmal.MMAL_PARAMETER_FRAME_RATE] - self.framerate)