I want to synchronize the stream projection of an environment video (youtube stream) with some geometrical objects drawn in it (e.g. little non intersecting circles) in such a way that a user on a smartphone or pc monitor can select one object simply by putting the mouse or finger on the screen position where one circle object is. Then the system generates an audiovisual event which is transmitted through the stream. All the geometrical objects are computed and drawn before streaming them so that the client side code at first has no position info where to find them on the user screen.
I mean can I arrange it securely for all user devices that the x/y position of the sketch correponds to the xy position of the user screen so that the system identifies the x, y pixel position of any object resp. that mouseX / mouseY are inside one circle? Some experience based feedback I would appreciate.