How to record a live stream in flutter

Question

Can someone let me know please a cost efficient way of saving live stream from a user's camera to a cloud storage.

I want to record the live stream as soon as video bytes are recieved on the server.

I'm a noob in this. I researched about it and found RTMP server is used to live stream video. But what is used to record it as well in real time.

I don't know how to setup a rtmp server or anything but would like to follow any great tutorial if you have.

use case: A user can simply record whatever he wants directly in to my server and can later also play it in my flutter app