ATEM Mini
Description
Product description from BlackMagicDesign.com:
ATEM Mini features 4 HDMI inputs and has an intuitive, easy to use design that makes it possible for anyone to live stream multi camera productions online via services and software such as YouTube Facebook Live or even Skype. Simply connect 4 high quality HDMI inputs that can be used for live switching cameras, computers or even game consoles. You get a built in DVE for exciting picture in picture effects, broadcast quality transitions, upstream keyers for removing blue and green screen background, a downstream keyer for superimposing custom graphics, audio inputs a mixer, and more. To stream, ATEM Mini also has a USB output that works like a webcam, so you can connect to any video software. There's also HDMI video out for projectors.
More product info here: https://www.blackmagicdesign.com/products/atemmini/techspecs/W-APS-13