node-mic

node-mic

A cross-platform Node.js package for recording audio streams from a microphone.

Installation

Node-mic uses arecord on Linux and sox on Windows and macOS. If sox is not already installed, node-mic will attempt to download the latest version.

On the new M1 Mac, that requires installing brew.sh (Intel Macs should work fine without it).

On Linux, it will warn if arecord is not found and remind you to install it using your package manager.

On Debian-based distros, try running this:

sudo apt-get update && sudo apt-get install alsa-utils

On RedHat-based distros, try running this:

sudo dnf install alsa-utils

After that's done, you can try testing it to make sure your microphone is detected.

arecord temp.wav

Example

import fs from 'fs';
import NodeMic from 'node-mic';

const mic = new NodeMic({
    rate: 16000,
    channels: 1,
    threshold: 6
});

const micInputStream = mic.getAudioStream();
const outputFileStream = fs.createWriteStream('output.raw');

micInputStream.pipe(outputFileStream);

micInputStream.on('data', (data) => {
    // Do something with the data.
});

micInputStream.on('error', (err) => {
    console.log(`Error: ${err.message}`);
});

micInputStream.on('started', () => {
    console.log('Started');
    setTimeout(() => {
        mic.pause();
    }, 5000);
});

micInputStream.on('stopped', () => {
    console.log('Stopped');
});

micInputStream.on('paused', () => {
    console.log('Paused');
    setTimeout(() => {
        mic.resume();
    }, 5000);
});

micInputStream.on('unpaused', () => {
    console.log('Unpaused');
    setTimeout(() => {
        mic.stop();
    }, 5000);
});

micInputStream.on('silence', () => {
    console.log('Silence');
});

micInputStream.on('exit', (code) => {
    console.log(`Exited with code: ${code}`);
});

mic.start();

The above example should save the output to a file named output.raw. Note that arecord pipes the 44 byte WAV header, whereas SOX does not. So we need to provide the file format details to the player:

aplay -f S16_LE -r 16000 -c 1 output.raw # Linux

or

play -b 16 -e signed -c 1 -r 16000 output.raw # Windows/Mac

API

Mic(options)

Creates a new microphone object. It inherits all the events from stream.Transform.

Accepts the following parameters (all optional):

• options
  • endian: Endian format. (default little)
  • bitwidth: Bit size. (default: 16)
  • encoding: Signed or unsigned. (default: signed-integer)
  • rate: Bit rate. (default: 16000)
  • channels: Number of channels. (default: 1)
  • device: Which device to use. Linux only. (default: plughw:0,0)
  • threshold: The 'silence' signal is raised after reaching these many consecutive frames. (default: 0)
  • fileType: Recording format. raw or wav. (default: raw)
  • debug: If true then extra debug information is printed. (default: false)

mic.start()

Starts the recording. Emits the 'started' signal.

mic.stop()

Stops the recording. Emits the 'stopped' signal.

mic.pause()

Pauses the recording. Emits the 'paused' signal.

mic.resume()

Resumes the recording. Emits the 'unpaused' signal.

mic.getAudioStream()

This returns a simple Transform stream that contains the data. The stream can be directly piped to a speaker or a file.

mic.on('data')

This signal is emitted every time data is available. data is an audio waveform.

mic.on('exit')

This signal is emitted when the recording process has finished.

mic.on('error')

This signal is emitted whenever an error occurs.

License

The MIT License (MIT). See LICENSE for more information.

Copyright (c) 2021 Alex Shaw [e-mail]

Forked from mic.

Copyright (c) 2016 Ashish Bajaj [e-mail]