@audio/dynamics-compressor

Feed-forward soft-knee compressor (Giannoulis-Massberg topology)

npm install @audio/dynamics-compressor

import compressor from '@audio/dynamics-compressor'

Feed-forward soft-knee downward compressor — Giannoulis-Massberg topology. Envelope → log domain → quadratic soft-knee gain curve → linear gain applied to input.

Downward compression (above threshold, reduces gain) is one half of the canonical four-quadrant dynamics taxonomy — downward/upward compression, downward/upward expansion (Giannoulis, Massberg & Reiss 2012; Izhaki, Mixing Audio). Setting upThreshold engages the other compression half: upward compression lifts quiet passages toward the threshold instead of squashing loud ones — the "OTT up" half popularized by Xfer OTT. Both curves read the same envelope and sum in the dB domain, so a single compressor call can glue loud material down and lift quiet material up at once.

import { compressor } from '@audio/dynamics'

compressor(data, { threshold: -18, ratio: 4 })
compressor(data, { threshold: -24, ratio: 2, knee: 12, attack: 10, release: 200, makeup: 6 })

// upward + downward together (OTT-style): lift quiet passages, squash loud ones
compressor(data, { threshold: -18, ratio: 4, upThreshold: -40, upRatio: 2, upRange: 12 })

| Param | Default | | |---|---|---| | threshold | -20 | dB | | ratio | 4 | — | | knee | 6 | dB (soft-knee width) | | attack | 5 | ms | | release | 100 | ms | | makeup | 0 | dB | | depth | 1 | scales the summed up+down gain before makeup (OTT "Depth" macro; 0 = identity) | | upThreshold | null | dB; null disables upward compression | | upRatio | 2 | — (1 is a mathematical no-op) | | upKnee | 6 | dB | | upRange | 12 | dB, max upward lift — without a ceiling, silence would take unbounded gain |

Use when: vocals, bass, drum bus, mix glue; add upThreshold for OTT-style up+down "aggressive" glue. Not for: peak control at the master bus — use limiter. Transparent loudness shaping — use compand with gentle slope.

Part of @audio/dynamics — the dynamics family umbrella. This README is generated from the umbrella docs.

MIT © audiojs