Processor · Audio effect
Quefrency
Splits each frame through the cepstrum into a formant envelope and a harmonic structure, shifts and reshapes each independently, and multiplies them back together — with the latency the web version never reported now declared to the host.
Opinion
The formant knob is the one: +7 semitones on a vocal-ish pad lifts the vowels without touching the notes, which no plain pitch shifter can do. The price is the usual phase-vocoder smear on transients and a two-thousand-sample delay the host has to swallow — both honestly declared. Keep the lifter below the shortest pitch period or the whole trick leaks.
Functionality
Quefrency is a port of the JigDAW plugin of the same name (Rust/WebAssembly). Each stereo frame (2048 samples at 50 kHz and below, 4096 above, hop a quarter) is FFT’d; the log magnitude is cepstrally smoothed at the lifter split into a formant envelope and a harmonic excitation; the envelope is warped (shift), contrasted (depth) and tilted; excitation peaks move by pitch ratio and Hz offset with Laroche–Dolson phase rotation; everything is applied as a gain on the input spectrum, so neutral settings reconstruct the input exactly, delayed by N−1. The dry path carries the same delay, so half mix does not comb.
Latency is 2047 samples at 50 kHz and below, 4095 above, and is reported to the host — the web module ABI carries no latency field, which is the timing problem this port fixes. MIDI CC 70–80 drive the eleven parameters in order on any channel with centre-detent mapping; a CC holds until the host moves that control.
Parameters
| Parameter | Range | Default | Notes |
|---|---|---|---|
| Formant shift | −12…+12 st | 0 | Envelope axis warp. CC 70 |
| Formant depth | 0–200 % | 100 % | 0 flattens, 200 exaggerates. CC 71 |
| Formant tilt | −6…+6 dB/oct | 0 | About 1 kHz. CC 72 |
| Pitch shift | −24…+24 st | 0 | Peak ratio. CC 73 |
| Pitch fine | −100…+100 ct | 0 | Peak ratio trim. CC 74 |
| Freq shift | −1000…+1000 Hz | 0 | Inharmonic offset. CC 75 |
| Harmonic depth | 0–200 % | 100 % | 0 breathy, 200 buzzy. CC 76 |
| Lifter | 0.5–5 ms | 1.5 ms | Cepstral split point. CC 77 |
| Estimator | Cepstral, True envelope | Cepstral | CC 78 |
| Mix | 0–100 % | 100 % | Dry delayed to match. CC 79 |
| Output | −24…+12 dB | 0 dB | CC 80 |
Status
Core DSP, deterministic tests, the VST3 target, the panel and the catalogue screenshot are complete. Host validation in REAPER remains.