How difficult is it to make a peer-2-peer bi-directional video stream between two Androids?

Question

Android

As far as I understand, Skype & Co use central servers not only because of accounts, but also by processing the stream (transcoding) there. If you drive video from the camera of one Android via RTP, it will certainly be fast, but you can’t show the RTP stream on the other side, you need to turn on some kind of econder, which of course will load either the receiver or transmitter smartphone.
Although there are ready-made applications such as IP WebCam that give streaming to the client's browser, for example.
Can respected experts point out where to dig to make a similar application on their own?

Answer 1

www.kurento.org
https
://simplewebrtc.com/quickblox.com/developers/Authentication_and_Author...