Need Guidance on Implementing Custom Designs and Background Effects for Videos [closed]

I am currently developing a web application that allows users to upload videos on the frontend. The primary goal of my project is to enable users to add custom designs to their videos and apply background effects. I’m using Python for the backend to handle video processing.

I’m seeking advice on the appropriate technologies, libraries, or approaches to achieve the following:

1. Custom Designs: I want to provide users with the ability to overlay custom graphics or text onto their videos. What Python libraries or tools can I use to achieve this? Are there any best practices for adding graphics and text to videos dynamically?
2. Background Effects: I need to implement the feature to add background effects to uploaded videos. How can I achieve this, and what are the recommended methods or libraries for background replacement or manipulation?
3. Shadow Effects: Additionally, I want to enhance the visual appeal of the videos by adding shadow effects to elements like text or custom designs. What techniques or tools should I explore to achieve this effect?
   4.Combining Videos: To apply background effects, I need to merge the uploaded video with a background video or image seamlessly. What is the best approach to combine videos and maintain video quality during the process?

I have already implemented the frontend video upload to the backend and would appreciate any insights, code examples, or recommendations that can help me achieve these features effectively.