Update: Since writing this post Luke Stein pointed me to an app called H2R Graphics, which lets you overlay a timer on your computer if you have a setup like an ATEM Mini. It’s a little funny to set up – you plug your computer into the ATEM, and then back from the ATEM to the computer – but the result is a pretty flexible timer that’s quite useful!
While in meetings or teaching, it’s often useful to have a timer visible to everyone to help keep track of time. I was interested in having this overlaid atop my video and, using the Chroma key function of my ATEM Mini, I was able to do so.
The secret is creating a video or presentation of a countdown timer with some kind of green background. I did this by creating Keynote presentations with this AppleScript and then exporting them as movies. Lucky for you, I’ve posted a few sample timers here for two, five, and ten minutes.
Once I’ve created the timers, I just plug in my camera into one source of my ATEM Mini, and my iPad into a second source, and overlay them in the following way:
Pretty spiffy, and quite useful!
P.S. It’s easy to do this much more cheaply using OBS. Just right click on the video source in the list of Sources (it can be your iPad, or you can download one of the videos from above and use it as a Media Source), click “Filters,” click the plus sign under “Effect Filters” and select “Chroma Key,” and make sure the Key Color Type is set to Green. Voila!