it's a variable delay buffer - there's m4l.vdelay~ too.

Try dynamically changing the delay time on both - the variable delay buffer will do it without repitching, it'll do a little crossfade instead.

...it just sounds differently in those scenarios. If you just want plain echo, then they're identical.

Right, when you change the delay time of tapout~ using a float, you'll get a click, and when you change the delay time using a smoothed signal you'll get transposition during the "moving period". m4l.vdelay~ abstraction is part of the standard distribution and does basically the same thing, so you can use that without worrying about installing third party library, even as cool as the ejies ;-)