How to implement speed into this?

[FaizelK]

I would like to add speed, so I the "webcam or video" is seen as the driving vehicle.

I know that speed is distance over time. So i get the frames per second keep record of the distance travelled per frame, i should be able to estimate speed.

def calculate_fps(cap):
count_frames = 0
start_time = time.time()

while True:
    # Read the next frame from the video file
    ret, frame = cap.read()
    count_frames += 1

    if ret:
        elapsed_time = time.time() - start_time
        current_fps = count_frames / elapsed_time
        break
    else:
        break

return current_fps

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

if ret:	

	# Detect the lanes
	output_img = lane_detector.detect_lanes(frame)

	fps = calculate_fps(cap)

	# Calculate speed
	ym_per_pix = 0.2  # meters per pixel
	speed = np.sum(lane_detector.distances[-int(fps):], axis=0) * ym_per_pix * fps * 3.6 # km/h

	average_speed = round(np.mean(speed))
	print('Average Speed:', average_speed, 'km/h')

I know i have to initial and keep record of distances variable inside UltrafastLaneDetector class. How can i go about doing this? is this the right approach?