Coding the vehicles counting algorithm in a traffic video.

Hello, I have been trying to figure out how to count the vehicles in traffic video. I have been following the code provided by MATLAB in the link below.

CODE LINK

This approach is able to detect the cars and count the number of moving objects in the current frame. I am new to image processing and computer vision, so not exactly sure about how figure out the way to keep a count of how many vehicles are passing the road. I don't want to count the moving objects in the current frame but I am interested in keeping the count of vehicles throughout the video.

I will appreciate any help regarding this.

Thank you for your time and consideration in advance. Aditya.