---------------------------- Original Message ---------------------------- Subject: Re: [music-dsp] Real-time pitch shifting? From: "Chris Cannam" <[email protected]> Date: Mon, May 21, 2018 3:35 pm To: [email protected] -------------------------------------------------------------------------- > > On Mon, 21 May 2018, at 19:54, Matt Ingalls wrote: >> "Rubber Band implements pitch-shifting using the standard technique of >> resampling… >> This method has the advantage of making the amount of pitch adjustment >> extremely accurate and stable, even for small changes.” Rubber Band sounds pretty good to me and to my ears made of clay.� i thought, back in my day, that SPEED (SoundToys) sounded pretty good. � > It also means you only have to solve the auditory problem once -- if you can > keep the artifacts down for the time stretcher, then pitch-shifting is free. unless you're gonna worry about formants, pitch shifting is just resampling applied to the output (or input) of a time scaler.� i would do whichever operation increases the data first.� so pitch shifting up would be time-stretch first, then resample.� pitch shifting down would be resample first and then time-compress. > Unfortunately it does create some complications in terms of managing the > proper frame timing and so on. resetting the frame alignment whenever a transient is detected is a real pain in the ass.� but the idea to do that then let the phases drift (glitchlessly) after the transient is a good idea.� doesn't seem to solve the phasiness problem for human voice when pitches change but no transient is detected (then phases can get outa alignment again).� i really don't know a clean way of keeping those phases well aligned. � > I assume this wouldn't work with your use-case as you want to keep the frames > synchronised so you can resynthesise everything in one go. it would need more buffering, but you can do it real-time, even with the frames being reset and initially aligned with a transient.� but it gets complicated and the throughput delay gets large. -- r b-j� � � � � � � � � � � � �[email protected] "Imagination is more important than knowledge." � � � �
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