DSP Robotics Support

I lately looked into martin's pitch shifter's schematic which he shared here few years a go and found out a curious feature that allows time stretching of the loaded sample with a knob that simply called "time". I'm interested in this because of possibility to do some really cool things like maybe syncing a loaded sample to a given BPM (without any additional pitch shifting manipulation).

So Martin, if you read this, I would love to get some help with it or at least understand if thing like that is doable with FS.

Thanks.