this is very cool.� i had not read through everything, but i listened to all of 
the sound examples.
so there are two things i want to ask about.� the first is about this 
"granular" semantic:

Thing #1:� so the pitch shifting is apparently *not* "formant-corrected" or 
"formant-preserving".� when you shift up, the voice becomes a little 
"munchkinized" and when you shift down, Darth Vader (or Satan) comes through.� 
that's okay (unless one does
not want it), but i thought that with granular synthesis (or resynthesis), that 
the grains that are windowed off and overlap-added where not stretched (for 
downshifting) nor scrunched (for up-shifting).� i.e. i thought that in granular 
synthesis, the amount of overlap increases in up shifting
and decreases during downshifting.� this kind of pitch shifting is what Keith 
Lent writes about in Computer Music Journal in 1989 (boy that's a long time 
ago) and i did a paper in the JAES in, i think, 1995.
without this formant-preserving operation, i think i would call this either
"TDHS" (time-domain harmonic scaling), "OLA" (overlap-add), or "WOLA" (windowed 
overlap-add), or if pitch detection is done "SOLA" (synchronous overlap-add) or 
"PSOLA" (pitch synchronous overlap-add).� however i have read somewhere the 
usage of
the term PSOLA to mean this formant-preserving pitch shifting a.la Lent (or 
also a French dude named Hamon).� BTW, IVL Technologies (they did the 
pitch-shifting products for Digitech) was heavy into this and had a few 
patents, some i believe are now expired.
Thing #2: are you doing any
pitch detection or some attempt to keep waveforms coherent in either the 
time-scaling or pitch-shifting applications?� they sound pretty good (the 
windowing smoothes things out) but might sound more transparent if you could 
space the input grains by an integer number of periods.
pitch-detection and careful cross-fading (and windowing can be thought of as a 
fade-up function concatenated to a fade-down function) you can make 
time-scaling or pitch-shifting a monophonic voice or harmonic instrument glitch 
free.� it can sound *very* good and companies like Eventide have
been doing something like that since the early-to-mid 80s.� (ever since the 
H949.)� and i imagine any modern DAW does this (and some might do 
frequency-domain pitch-shifting and/or time-scaling using something we usually 
call a "phase vocoder".
but your
examples sound pretty good.
r b-j

---------------------------- Original Message ----------------------------

Subject: [music-dsp] granular synth write up / samples / c++

From: "Alan Wolfe" <alan.wo...@gmail.com>

Date: Mon, March 5, 2018 5:14 pm

To: "A discussion list for music-related DSP" <music-dsp@music.columbia.edu>


> Hey Guys,


> Figured I'd share this here.


> An explanation of basic granular synth stuff, and some simple standalone

> C++ i wrote that implements it.


> https://blog.demofox.org/2018/03/05/granular-audio-synthesis/


> Kind of amazed at how well it works (:


> Thanks for the answer to my question BTW Jeff.

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r b-j� � � � � � � � � � � � �r...@audioimagination.com

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