I am the one of the cycling captain of UEA Triathlon Club for the academic year of 2017-2018. I always find it hard to keep track of the set in a turbo session for some reason.
I used to use a Matlab-based countdown timer [(https://uk.mathworks.com/matlabcentral/fileexchange/18165-countdown)]. However it always freezes after 558 seconds had elapsed - if you set a 10-minute countdown timer, it will freeze at 42 seconds. I can't be bothered to fix the Matlab code.
After digging through FFmpeg documentation [(https://trac.ffmpeg.org/wiki)] and the Internet, I figured out how to generate a text-based video.
I have to say FFmpeg is one of my most abused software. Last time I used FFmpeg to upload arbitrary file to Youtube [(https://github.com/fangfufu/Matlab-Data-Video-Converter)].
You can download it at https://github.com/fangfufu/make_interval_timer_video.