@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, as Giannoulis, Massberg & Reiss recommend: level in dB → quadratic soft-knee gain curve → gain reduction smoothed in the log domain by the smooth decoupled peak detector → linear gain applied to input. attack and release are the time constants of the gain reduction itself (1 − 1/e), at any depth of compression; the first sample over the threshold is already reduced.
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'
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