This is a PoC React implementation of DashWare, an app for adding speed, heart rate, cycling power and cadence overlays to action camera footage.
It works by parsing the .FIT file, extracting speed and power data, and using Etro to render a green screen with the data overlaid. The video can be previewed, rendered, and then imported into a video editor, and the green set as the transparency color.
The rendering itself is extremely slow, small files <1min are recommended.
File can be trimmed with FIT file tools.
It can be quite buggy as well, only tested with Garmin files with 1s recording interval. As rendering is so slow, there's no point to develop it further.