[feature] Add ability to speed-up/slow-down playback rate

[eharris]

It would be great if there were a way to be able to change the speed of playback (with pitch shift to maintain original timbre) for audiobooks or learning songs. 10% or 5% steps would be great.

[einsteinx2]

This is something I've wanted to add for a long time. I think it's doable with the Bass audio library's FX plugin. I'm currently focused on just getting feature parity with the App Store version in the new Swift rewrite, then will work on adding additional functionality like this, but I'm all for the idea.

It's also great for people that DJ and have their music collection in their library I do, since often I would like to listen to a song faster or slower the way I would DJ it. So there are even more useful use cases for this than even just audiobooks and learning material.