How to redirect and use the framebuffer?

I need to work on the framebuffer to record what is being rendered. Now, I figure out how to convert the framebuffer in an image, I'm currently unable to obtain a constant stream of data from the fb to create a video. /dev/fb > fb When I do something like this my redirection just drops me and I honestly don't know how to work in another way with the framebuffer. How I can obtain a stream?