Nirvenesh, we used overlay in our old version of software, before StereoPi even developed (look at the code here https://github.com/realizator/3dberry-turorial, and at the result with overlay depth map video with Raspberry Pi 2 series here https://www.youtube.com/watch?v=-qTayRg8skA). In our current StereoPi code (https://github.com/realizator/stereopi-tutorial) we rejected this approach, as Raspbian has no native support for overlayed stereoscopic video. But you can use our old code as an example to implement it. Please notice you’ll need to fix some code, as these examples was designed for older versions of Python and OpenCV.