@audio/stretch-psola

Pitch-Synchronous Overlap-Add. Detects pitch period via autocorrelation, windows grains at pitch-cycle boundaries, then re-spaces them — no phase discontinuities at overlaps.

import psola from '@audio/stretch-psola'

psola(data, { factor: 1.5 })
psola(data, { factor: 2, minFreq: 100, maxFreq: 400 })   // male voice range

| Param | Default | | |---|---|---| | factor | 1 | Time stretch ratio | | sampleRate | 44100 | For pitch detection range | | minFreq | 80 | Lowest expected pitch (Hz) | | maxFreq | 500 | Highest expected pitch (Hz) |

Falls through to WSOLA on unvoiced/polyphonic frames (autocorrelation peak < 0.72).

Use when: speech, solo vocals, monophonic instruments, factors 0.5–2×. Not for: polyphonic material, extreme ratios (>2× causes gaps).

Part of @audio/stretch.

License

MIT · ॐ