@audio/filter-comb

Comb filter — feedforward (FIR) and feedback (IIR)

npm install @audio/filter-comb

import comb from '@audio/filter-comb'

Adds a delayed copy of the signal to itself — notches and peaks at harmonics of $f_s / D$.

Feedforward: $H(z) = 1 + g \cdot z^{-D}$ — dips at $f = \frac{(2k+1) f_s}{2D}$, depth depends on $g$: a true null only at $|g|=1$; the default $g=0.5$ gives a $-6,\text{dB}$ dip, not a notch Feedback: $H(z) = \dfrac{1}{1 - g \cdot z^{-D}}$ — peaks at $f = \frac{k \cdot f_s}{D}$

comb(buffer, { delay: 100, gain: 0.6, type: 'feedback' })

| Param | Default | | |---|---|---| | delay | — | required, delay length in samples (D) | | gain | 0.5 | feedforward/feedback coefficient g | | type | 'feedforward' | 'feedforward' (FIR, dips) or 'feedback' (IIR, peaks) |

Pass the same params object on every call — the ring buffer and write pointer persist across blocks:

let params = { delay: 100, gain: 0.6, type: 'feedback' }
for (let buf of stream) comb(buf, params)

Use when: flanging, chorus (with modulated delay), Karplus-Strong string synthesis, room mode modeling.

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

MIT © audiojs