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
• bilinear
• biquad
• loudness
• lowpass
• hipass
• rumble
• flutter
• noise
• bessel
• butterworth
• matched
• elliptical
• linkwitz-riley
• chebyshev
• inverse-chebyshev
• savitzky-golay
• curve (custom f-curve)

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

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})

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)
}

bilinear(data, {order: 1, })

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

See also

• audio-filter − digital filters for audio infrastructure
• colors-of-noise − collection of noise generators