I'm currently helping to run a psychology experiment in which participants watch a video on a screen whilst having their eye movements tracked.
On the experimenter desk, we have one monitor which displays a duplicate of what the participants can see (i.e. the video), and another, where their eye movements are displayed in real time. This is shown as a blank box in the corner of the screen, with a dot which moves around showing their fixation. Both of these are connected to their respective PCs using a VGA cable, as is the larger screen which participants watch.
Basically, we would like to add a third screen which combines these two views. In other words, I would like to - in real time - overlay the box from the eye tracking screen onto the video feed. I imagine it would be necessary to select the background colour of the box to be filtered out, select the box as the area of the screen I would like overlaid, and then stretch it so that it covers the entire area of the video.
Does anyone have any idea how this might be achieved? In a previous but similar setup this was done using a BlackMagic Media Express, as well as two "scan converters", a TVone Cs-320 Connect, by Corio; and a Scan Converter AVT-3170, by AVTool. However, I am unsure if these are still needed, since monitor resolutions have advanced so much in the meantime. I contacted blackmagic support, who pointed us towards an ATEM switcher (https://www.blackmagicdesign.com/uk/products/atem), which they said could "overlay any input over another with the ability to move it, resize it, key it and put borders on it". This sounds promising, but will we need any of the "scan converter" things as well? What do they even do? We are wary of spending so much money for something which might not work
I'm sorry for such basic questions, but media is really not my strong suit. Any information you can offer which might help us would be more than welcome. We're not committed to BlackMagic hardware either - any hardware which can achieve this would be a potential alternative.
Thanks very much for your time!