Drambo how to make time/pitch stretch from scratch?

Panthemusicalgoat

Drambo continually blows me away. I’ve managed to reproduce just about every synth patch I’ve made in other apps with it as well as make really unique new sounds. I recently came across Ben Richard’s glacial time stretch/granulated patch he made on patchstorage. Really cool stuff It slows the tempo down without changing pitch by using a very small buffer rescan.

https://patchstorage.com/glacial-sampler-time-stretch-texture-sampler/

I’m curious if it’s possible to make a custom pitch shifter using the same principle? Also is there some way to do poly pitch detection for audio-> midi?

@rs2000 might know?

rs2000

Sure, first of all, there's already a Pitch Shifter module available in Drambo.
But you could also work with tiny slices of modulated delays that you might want to crossfade or soft-enveloped-mix into each other. Modulated delay itself gives you a clean pitched-up or pitched-down or even a reversed version of your input signal but it's changed in speed as well so you need to work with small slices of audio in order to work around that.
The fine art in pitch shifting has always been about how to adjust all these tricks to sound good on any input signal.
Detecting transients (using the Envelope Follower for example) can help.

Poly audio to MIDI is rather easy as long as your chords are composed of sinewaves - in that case you could make a bank of bandpass filters and envelope followers and create MIDI notes when certain thresholds are detected (I admit that's a very simplified case but there's a reason why software developers have struggled to achieve robust polyphonic audio to MIDI for a long time )

Panthemusicalgoat

Thanks @rs2000 for the solid explination. Yea the pitch shifter module in Drambo is surprisingly quick and decent sounding. I was just interested in making a custom one from scratch I could play with the inner workings of and understand how it functions.

So what would the chain signal and modules look like?

square osc used as LFO to retrigger the buffer scan sandwiched inside a delay rack?

Pretty knowledgeable about synth architecture but not so much how pitch shifting works.

rs2000

@Panthemusicalgoat said:
Thanks @rs2000 for the solid explination. Yea the pitch shifter module in Drambo is surprisingly quick and decent sounding. I was just interested in making a custom one from scratch I could play with the inner workings of and understand how it functions.

So what would the chain signal and modules look like?

square osc used as LFO to retrigger the buffer scan sandwiched inside a delay rack?

Pretty knowledgeable about synth architecture but not so much how pitch shifting works.

There are many online resources detailing on the various approaches to pitch shifting, I'd recommend to read them first and let them guide your way through re-building something in Drambo.
Making a high quality pitch shifter is certainly not an easy task but I'm sure that on your way, you'll stumble over a number of other fun audio effects worth expanding 😊

rs2000

Here's a nice paper detailing on two time-domain methods (OLA & PSOLA) that work best with monophonic signals:
http://www.diva-portal.org/smash/get/diva2:1381398/FULLTEXT01.pdf