Looking for a specific type of "video-editing" library

Hi all, i m new in this Forum and as android developer, i m italian therefore sry for my bad english.
I was looking for a specific type of “video-editing” library, i need to create a “video-collage” composed of more videos played concurrently, can i have some tip or a library name that allows me to do that? Ty all
Here an example of what i aiming