Secretmapper / node-speex-resampler

An implementation of Speex audio resampler on NodeJS with N-API

Speex Resampler

This lib exposes the Speex resampler to Javascript with WebAssembly. It doesn't have any dependancy and support NodeJS or a WebContext. Typescript typings are also provided.

From speex creator, the design goals of the resampler are:

• Very fast algorithm
• SIMD-friendly algorithm
• Low memory requirement
• Good perceptual quality (and not best SNR)

How to use

await SpeexResampler.initPromise; // will be resolved once the WASM module has been compiled, before this you cannot call the SpeexResampler processChunk method

const channels = 2; // minimum is 1, no maximum
const inRate = 44100; // frequency in Hz for the input chunk
const outRate = 44000; // frequency in Hz for the target chunk
const quality = 7; // number from 1 to 10, default to 7, 1 is fast but of bad quality, 10 is slow but best quality
// you need a new resampler for every audio stream you want to resample
// it keeps data from previous calls to improve the resampling
const resampler = new SpeexResampler(
  channels,
  audioTest.inRate,
  audioTest.outRate,
  audioTest.quality // optionnal
);

const pcmData = Buffer.from(/* interleaved PCM data in signed 16bits int */);
const res = await resampler.processChunk(pcmData);
// res is also a buffer with interleaved signed 16 bits PCM data

You can look at the src/test.ts for more information.

Test music by https://www.bensound.com