Try building up a method iteratively. Start by calculating the speed of a car as it crosses the camera frame.

Then try calculating the speed between two points (in car length in front of and a car length behind the stop sign).

Then set a threshold for how fast is too fast for a car to realistically go between those two points without stopping. Get notified with a video snippet when a car is above this threshold. Adjust the threshold based on the videos you are capturing.

It won’t work if your object detection is not running at your camera framerate.