On Sat, 19 May 2018, at 21:34, RJ Skerry-Ryan wrote: > It may not be the state of the art, but RubberBand > <https://breakfastquay.com/rubberband/> is, I believe, the best open source > pitch shift / time stretch library out there at the moment, and can run in > realtime on modern CPUs.
See here for a page very briefly summarising how Rubber Band works: https://breakfastquay.com/rubberband/technical.html In short, it's a phase vocoder that uses a handful of the available tricks to try to reduce phasiness, without doing any very expensive analysis such as sinusoidal modelling. There is actually a fine sinusoidal-modelling time stretcher hiding in Audacity, using the SBSMS library by Clayton Otey. This isn't a real-time method as far as I can see, and is slow to run, but it's worth checking out -- you activate it by selecting the Change Tempo or Change Pitch effect and checking the option labelled "Use high quality stretching". Code at https://github.com/audacity/audacity/tree/master/lib-src/sbsms. Stephan Bernsee's old post is a bit of a puzzle, since it contains quite a lot about analysis/resynthesis but very little about actual pitch shifting. Chris _______________________________________________ dupswapdrop: music-dsp mailing list music-dsp@music.columbia.edu https://lists.columbia.edu/mailman/listinfo/music-dsp
