I wrote this working POC to give any lifters with some Python knowledge and a webcam a chance to try a VBT program without committing to shelling out any serious cash for a device.

The app will detect a solid green area painted on to the end of your barbell. Given the measured diameter of this circle it will determine the pixel per mm scale to calculate distances and velocities of the barbell.

When the detects a rep, it displays the most commonly referenced VBT metrics and informs you if your lifts are within 0.5-0.75 m/s as well as if they fall below a 20% velocity cutoff. There is an audible signal that is played of your lifts comply or fall outside of the range so you know when to terminate your set without having to keep your eyes on the computer.

The display tells you what rep you're on, the displacement of the bar, the velocity of the concentric part of the lift and whether the art should be terminated.