Show Caller ID, Webcam image as overlay on TV

Is there a way to show callerid, webcam images and other things on tv as overlay? I have an lg tv and use they binding, to really working for some things like open app, push browser url. So i wonder if there is another way to show info on screen while watching tv for example. Maybe use an raspberry pi, stream hdmi into pi, add overlays and output to tv?

Anybody with ideas or maybe solutions for that?

I am able to do all of this, but only if I am watching/viewing XBMC/KODI - which is probably 80% of the time. I get notifications via the XBMC target of mqttwarn, and security camera overlays via this XBMC addon.

I do like the idea of a more generic solution for all HDMI signals passing to my TV so will be watching this thread with interest to see if anyone else has a better solution than mine.

Something like this: ?