Pitch shift in cents?

Jazzer73 · July 23, 2025, 11:01am

Hi!
Is there a way to make the included pitch shifter work in cents instead of semitones, or is there something else I could use to get a detuning effect on an audio signal? Could I modify the pitch shifter library and make my own variant?

nopayne · July 23, 2025, 5:32pm

Based on the code it looks like it’s hardcoded to work in semi tones.

It’s probably possible to make a copy and modify it for your needs. I think the biggest hurdle is understanding if the ‘semitone_ratios_’ lookup table is needed. Maybe it’s for performance reasons?

xconverge · July 24, 2025, 4:50am

I used the pitch shifter from here: Fix/pitch shift by stephenhensley · Pull Request #166 · electro-smith/DaisySP · GitHub

The set transpose function in the pitch shifter class accepts a float without quantizing it to semitones so you are not limited to just semitones (like if it were a integer). If there are 100 cents in a semitone, then setting the transpose to 1.01 would be 1 cent, 1.02 is 2 cents, etc

I have some code here that acts like the digitech ricochet in momentary mode

github.com/bkshepherd/DaisySeedProjects

Software/GuitarPedal/Effect-Modules/pitch_shifter_module.cpp

main

#include "pitch_shifter_module.h"

#include <algorithm>

#include "../Util/pitch_shifter.h"
#include "daisysp.h"

using namespace bkshepherd;

static const char *s_semitoneBinNames[8] = {"1", "2", "3", "4", "5", "6", "7", "OCT"};
static const char *s_directionBinNames[2] = {"DOWN", "UP"};
static const char *s_modeBinNames[2] = {"LATCH", "MOMENT"};

// How many samples to delay to based on the "Delay" knob and parameter
// when the time knob is set to max, this is used for the ramp up/down
// transition when in momentary mode. Has no effect on latching mode
const uint32_t k_maxSamplesMaxTime = 48000 * 2;

// Larger delay size is higher fidelity/quality for a farther transpose, at
// the cost of additional latency (like...a lot of latency)

This file has been truncated. show original

start at 0:42 for momentary mode where this is relevant

and it sets the transpose target constantly (as a float)

Jazzer73 · July 24, 2025, 8:00am

Thx a lot! I´m getting in to this later today. Just hope I’ll figure out how to implement this in my own project written in daisyduino!

Jazzer73 · July 24, 2025, 3:41pm

I got it working with the edited library you pointed me to, much appreciated! The chains of the semitones now broken