How to implement an overlay overlay on a video stream based on Raspberry PI \ Orange Pi, etc.? Or Picture in Picture?

Question

Video broadcast

Hello! Throw in an implementation or a picture-in-picture idea.
There is a TV ress tricolor. There are 2 TVs and an HDMI hub. The same image from the set-top box is transmitted to 2 TVs. I would like to show information in the form of a running line and a picture with a set interval of time, on top of the main image in a certain place or several pictures in several places. Also, the ability to display gifs and videos. Interested, as well, udalenka. Only raspberries come to mind, but I'm not very familiar with raspberries.

This is how it should look like in the end.
As a matter of fact it is necessary: ​​To
pick up a video signal
In real time to superimpose a picture on it, such as on a photo. Send to TV through the hub.
All this should be done automatically when an electric power is supplied or by manually pressing the raspberry power button. Pictures (frames) of the overlay will have to change at a given interval. The overlay should turn on and off automatically.
Expensive pieces of iron are not interested.
A computer on Windows is also not interesting.
We need a compact little stray (a few priblubs), such as:
raspberry
capture board for raspberries

Answer 1

fpga only