4 ms·

You can transparently slow music without changing the pitch or pitch music without changing the tempo far more than 2%, which was what was done here. This techn

• cannam 5y ago
  I agree with you that you can often do this in a way that is still pleasant to listen to. But timestretching/pitch shifting is very far from being transparent in the way that a decent resampler is. Even a small shift will introduce some audible artifacts in most music. Will they be more or less apparent to the listener than the difference between recordings tuned to A=440 or 432 would be? I don't know. Depends on the music and the listener, I imagine. That would (be one of the many, many unstated things that would) matter to a paper like this. (For what it's worth, I wrote and maintain a widely-used timestretcher library. Possibly this means I am more aware of the limitations than the strengths of such technology)
• marcan_42 5y ago
  There is no way to do this with no artifacts; it's just fundamental to how audio works. We have pretty good algorithms for it, but in the end you're doing psychoacoustics to try to make it sound good. There's no mathematical model for doing this "perfectly" like there is for resampling. It's not hard to hear the artifacts in DJ tempo stretch algorithms if you listen closely, especially when they are applied to a full mix (as opposed to single instruments). Of course they're small these days, but when you're trying to measure a subtle effect, they're too much of a confounding variable.