[henningo]

Did you consider doing spline fits to the x,y coordinates and then just saving the spline coefficients instead?

The fit process could likely be done client-side, and could offer some subtle smoothing if wanted?

Anyhow, really nice execution!

[byoung2]

paper.js has a nice method to do this. I actually used it in a whiteboard app I made as a proof of concept. Rather than saving every X,Y coordinate, it uses a configurable number of points and handles and makes bezier curves. http://paperjs.org/examples/path-simplification/