@e9g/buffered-audio-nodes-utils

Shared DSP utilities for the buffered-audio-nodes ecosystem.

Install

npm install @e9g/buffered-audio-nodes-utils

Peer dependency: @e9g/buffered-audio-nodes-core

API

STFT / FFT

import { stft, istft, fft, ifft, hanningWindow, MixedRadixFft } from "@e9g/buffered-audio-nodes-utils";

| Function | Description | | --- | --- | | stft(signal, fftSize, hopSize, window?) | Short-Time Fourier Transform with tiered backend dispatch | | istft(frames, fftSize, hopSize, window?) | Inverse STFT (overlap-add reconstruction) | | fft(real, imag) | Forward FFT (Cooley-Tukey radix-2, in-place) | | ifft(real, imag) | Inverse FFT (in-place) | | hanningWindow(size) | Generate a Hann window of the given size | | MixedRadixFft | FFT class for non-power-of-2 sizes | | createFftWorkspace(size) | Allocate reusable FFT scratch buffers | | bitReverse(...) | Bit-reversal permutation | | butterflyStages(...) | Radix-2 butterfly computation |

const window = hanningWindow(2048);
const frames = stft(signal, 2048, 512, window);

// ... process frames ...

const reconstructed = istft(frames, 2048, 512, window);

FFT Backend

import { initFftBackend, detectFftBackend, getFftAddon } from "@e9g/buffered-audio-nodes-utils";
import type { FftBackend, FftBackendConfig } from "@e9g/buffered-audio-nodes-utils";

| Function | Description | | --- | --- | | initFftBackend(config) | Initialize the native FFT backend | | detectFftBackend(config) | Auto-detect the best available backend | | getFftAddon(config) | Get the loaded native addon |

The FFT backend uses tiered dispatch to select the fastest available implementation:

1. VkFFT (GPU via Vulkan) -- highest throughput for large transforms
2. FFTW (native CPU) -- optimized native fallback
3. JavaScript -- pure JS fallback, always available

stft and istft automatically use the best initialized backend.

await initFftBackend({ backend: "vkfft" });

Native addon repositories:

• VkFFT: visionsofparadise/vkfft-addon
• FFTW: visionsofparadise/fftw-addon

Biquad Filters

import {
	biquadFilter,
	zeroPhaseBiquadFilter,
	highPassCoefficients,
	lowPassCoefficients,
	bandPassCoefficients,
	preFilterCoefficients,
	rlbFilterCoefficients,
	bandpass,
} from "@e9g/buffered-audio-nodes-utils";
import type { BiquadCoefficients } from "@e9g/buffered-audio-nodes-utils";

| Function | Description | | --- | --- | | biquadFilter(samples, coefficients, state) | Apply a biquad IIR filter | | zeroPhaseBiquadFilter(samples, coefficients) | Zero-phase (forward-backward) biquad filter | | highPassCoefficients(frequency, sampleRate, Q?) | Design a high-pass biquad filter | | lowPassCoefficients(frequency, sampleRate, Q?) | Design a low-pass biquad filter | | bandPassCoefficients(frequency, sampleRate, Q?) | Design a band-pass biquad filter | | preFilterCoefficients(sampleRate) | BS.1770-4 pre-filter (high shelf at ~1500 Hz) | | rlbFilterCoefficients(sampleRate) | BS.1770-4 RLB weighting filter | | bandpass(signal, low, high, sampleRate) | Convenience bandpass using cascaded biquads |

const coeffs = lowPassCoefficients(1000, 48000);
const state = { x1: 0, x2: 0, y1: 0, y2: 0 };
const filtered = biquadFilter(samples, coeffs, state);

Channel Operations

import { interleave, deinterleaveBuffer, replaceChannel } from "@e9g/buffered-audio-nodes-utils";

| Function | Description | | --- | --- | | interleave(channels) | Interleave per-channel arrays into a single buffer | | deinterleaveBuffer(buffer, channelCount) | Deinterleave a buffer into per-channel arrays | | replaceChannel(samples, channelIndex, replacement) | Replace a single channel in an interleaved buffer |

Level Conversion

import { dbToLinear, linearToDb } from "@e9g/buffered-audio-nodes-utils";

| Function | Description | | --- | --- | | dbToLinear(db) | Convert decibels to linear amplitude | | linearToDb(linear) | Convert linear amplitude to decibels |

Envelope / Resampling

import { smoothEnvelope, resampleDirect } from "@e9g/buffered-audio-nodes-utils";

| Function | Description | | --- | --- | | smoothEnvelope(signal, attackSamples, releaseSamples) | Attack/release envelope follower | | resampleDirect(signal, fromRate, toRate) | Sample rate conversion via direct resampling |

License

ISC