What do you need to know to create a video calling app?

Question

Software design

I want to create applications for video communication (like Skype, only with different functionality and for a different purpose). You need 2 things: broadcasting your screen + voice and watching other people's screen.
What technologies are needed for this? What needs to be studied and read and how long can development take from an experienced specialist?

Answer 1

Search words: video streaming, wowza, red5, ffmpeg-server, rtmp
You need to know a lot, what exactly depends on the specific TK and the technologies chosen for its implementation