Digital-filter NPM

digital-filter

Collection of digital filters, for audio & dsp applications.

Usage

Produce 1024 samples of grey noise:

const noise = require('colors-of-noise/white')
const filter = require('digital-filter/loudness')

//generate frame of grey noise
let data = filter(noise(new Float32Array(1024)))

Filters

leaky integrator
moving average
biquad
loudness
lowpass
hipass
rumble
flutter
noise
bessel
butterworth
matched
elliptical
linkwitz-riley
chebyshev
savitzky-golay
curve (custom f-curve)

leakyIntegrator(samples, {lambda: 0.95, y: 0})

FIR

Leaky integrator.

Takes input array samples and params object, modifies samples in-place. Params object should be shared between subsequent calls.

Params:

lambda − defines amount of "leak".
y − keeps value of last sample, updated after every call.

let leaky = require('digital-filter/leaky-integrator')

let opts = {lambda: .5}

//render 3 frames
for (let i = 0; i < 3; i++) {
	let data = new Float32Array(1024)
	leaky(data, opts)
}

movingAverage(samples, {memory: 8})

FIR

Moving average.

Takes input array samples and params object, modifies samples in-place. Params object should be shared between subsequent calls.

Params:

memory − array with initial values of memory. If number, this will create an array of that size.

let ma = require('digital-filter/moving-average')

//average of 5 items
let opts = {memory: 5}

for (let i = 0; i < 3; i++) {
	let data = new Float32Array(1024)
	ma(data, opts)
}

loudness(data, {type: ''})

Implemented filter types:

a — A-weighting
b — B-weighting
c — C-weighting
d — D-weighting
z — Z-weighting (zero weighting)
itu — ITU-R 468 weighting

digital-filter v1.0.0