Fork of node-libsamplerate with prebuilt binaries and bug fixes

Installation

npm install jitinl/node-libsamplerate

Bug fixes

it is possible to use multiple libsamplerate streams in a chain. For example resampler1.pipe(mystream).pipe(resampler2). This does not work in the original implementation as there's only a single options structure shared throughout the library, so the options applied to resampler1 would end up applying to resampler1 as well.
uses node-gyp instead of cmakejs
comes with prebuilt binaries
uses the latest version of libsamplerate

Development

To update or add prebuilt binaries for your platform:

Build the latest libsamplerate code.
Copy over the libsamplerate.a file to the folder corresponding to your platform in the /lib folder in this project directory. If there's no folder corresponding to your platform, make one (refer to lib/copylib.js for the folder name ). Otherwise just place the libsamplerate.a file directly in the lib folder.
to now make prebuilt binaries for your platform,

npm run prebuild
To upload them as github releases,

export GITHUB_TOKEN=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

npm run upload

node-libsamplerate

ABI stable native implementation of libsamplerate as a Transform stream. Built from the latest libsamplerate code. Uses N-API, node-addon-api and cmake-js. This module has no external dependencies.

Introduction

Allows the upsampling/downsampling and/or upconverting/downconverting to/from arbitrary sample rates and to/from 16 or 32 bits per sample. Tested on Linux (x64 and arm), Windows and MacOS. This module uses the "Full Api" detailed here

Install

npm install node-libsamplerate --save

Requires cmake and a valid toolchain to build.

For Windows, install the Visual C++ build tools and download cmake from cmake.org. Or install Visual Studio with full c++ support.

Usage

Include module; const SampleRate = require('node-libsamplerate');

Instantiate: const resample = new SampleRate(options); where options is an object of the form:

let options = {
    // Value can be from 0 to 4 or using enum. 0 is the best quality and the slowest.
    type: SampleRate.SRC_SINC_MEDIUM_QALITY,
    // Stereo
    channels: 2,
    // Sample rate of source
    fromRate: 48000,
    // bit depth of source. Valid values: 16 or 32
    fromDepth: 16,
    // Desired sample rate
    toRate: 44100,
    // Desired bit depth. Valid values: 16 or 32
    toDepth: 16
}

Input audio data should be signed integers (e.g. S16_LE or S32_LE). Output will also be signed integers. Floating point input/output is not yet supported. Input should be from a readable stream, output should be to a writable stream: e.g.

const fs = require('fs');
let rs = fs.createReadStream('input.pcm');
let ws = fs.createWriteStream('output.pcm');

rs.pipe(resample).pipe(ws);

NOTE: if reading from a WAV file, start the read at 44 bytes to avoid the wav header ({start:44} for fs.createReadStream). If recording from arecord, sox or similar, use format raw.

Altering playback speed

This is possible by modifying the converter ratio, which can be done on the fly using the setRatio method. e.g. resample.setRatio(0.5). Depending upon timing, this will most likely take effect at the next buffer load. If fine grained modifications to playback speed are required, then a small value for highWaterMark on the input stream will be needed.

jitinl / node-libsamplerate