Creating custom tracking algorithm

Hello! I tested all variants of the available trackers, they work with varying success in my particular project. I thought that if i customize it, the accuracy of the application will increase. I need to take into account a number of physical features of the nature of the movement. How can i make changes to the tracking algorithm? What are the options? Where can I find the required source files? I would like to see how the existing algorithms are implemented in order to get in the know and think about what can be changed in them But I can't find their source. I think it will potentially relate to all other functions, if someone wants to delve into them, a similar question may arise, especially who do not understand how this package was created.