Resize a live stream and overlay over another live stream for broadcasting I'm working with ATEM Production Studio 4K from Blackmagic to switch between several video feeds that are broadcast using Wirecast onto Youtube from a Mac. Our ATEM product is not one of the switchers that comes with DVE (aka the ability to resize video input). I want to find a way to resize a video input and combine it with another input so I can broadcast the video to Youtube.

There are two video feeds I want to combine, a feed from presentation software and a feed from a camera filming a presenter, in a way that the presentation is smaller than full screen and moved to a corner.

I've considered ffmpeg, but I don't know how to use ffmpeg on a video stream in a way that we can combine it with another stream and send it into Wirecast, if that's possible.

An ideal solution would take a feed from our switcher and another feed from our presentation software, resize the presentation, combine it with the switcher feed, and send the result to Wirecast or Youtube. Is this possible to do for less than the cost of a new switcher? Is there a way to do this using OBS in place of Wirecast?
You can do this with OBS. I do it all the time.

The Mac, can with OBS take the feed(s) and arrange/resize them and then stream it to Wirecast(?, but not necessary) or directly to Youtube.

OBS handles both input from streams and from video cards, so you can have several inputs and combine them, very easily.