node-record-lpcm-16

Records a 16-bit signed-integer linear pulse modulation code WAV audio file.

This module uses Node.js streams to minimize memory usage and optimize speed, perfect for embedded devices and "the internet of things".

These audio files are fully compatible with both the Google Speech to Text API (v2) and the Wit.ai Speech API.

Installation

npm install node-record-lpcm16

Dependencies

Generally, running npm install should suffice.

This module requires you to install SoX and it must be available in your $PATH.

For Mac OS

brew install sox

For most linux disto's

sudo apt-get install sox libsox-fmt-all

For Windows

download the binaries

Options

sampleRate            : 16000  // audio sample rate
channels              : 1      // number of channels
threshold             : 0.5    // silence threshold (rec only)
endOnSilence          : false  // automatically end on silence (if supported)
thresholdStart        : null   // silence threshold to start recording, overrides threshold (rec only)
thresholdEnd          : null   // silence threshold to end recording, overrides threshold (rec only)
silence               : '1.0'  // seconds of silence before ending
recorder              : 'sox'  // Defaults to 'sox'
device                : null   // recording device (e.g.: 'plughw:1')
audioType             : 'wav'  // audio type to record

Please note that arecord might not work on all operating systems. If you can't capture any sound with arecord, try to change device (arecord -l).

Usage

const recorder = require('node-record-lpcm16')
const fs = require('fs')
 
const file = fs.createWriteStream('test.wav', { encoding: 'binary' })
 
recorder.record({
  sampleRate: 44100
})
.stream()
.pipe(file)

You can pause, resume and stop the recording manually.

const recorder = require('node-record-lpcm16')
const fs = require('fs')
 
const file = fs.createWriteStream('test.wav', { encoding: 'binary' })
 
const recording = recorder.record()
recording.stream().pipe(file)
 
// Pause recording after one second
setTimeout(() => {
  recording.pause()
}, 1000)
 
// Resume another second later
setTimeout(() => {
  recording.resume()
}, 2000)
 
// Stop recording after three seconds
setTimeout(() => {
  recording.stop()
}, 3000)

Recorders

The following recorders are included:

rec
sox
arecord

Note: not all recorders support all features!

Error handling

Some recorders might be logging errors to stderr and throw an exit code. You can catch early termination by adding an error event listener to the stream.

To debug the recorder see debugging below.

recording.stream()
  .on('error', err => {
    console.error('recorder threw an error:', err)
  })
  .pipe(file)

Debugging

Debug logging is implemented with visionmedia/debug

DEBUG=record node examples/file.js

Example

Here's how you can write your own Siri in just 10 lines of code.

const recorder = require('../')
const request = require('request')
 
const witToken = process.env.WIT_TOKEN // get one from wit.ai!
 
function parseResult (err, resp, body) {
  if (err) console.error(err)
  console.log(body)
}
 
const recording = recorder.record({
  recorder: 'arecord'
})
 
recording
  .stream()
  .pipe(request.post({
    'url': 'https://api.wit.ai/speech?client=chromium&lang=en-us&output=json',
    'headers': {
      'Accept': 'application/vnd.wit.20160202+json',
      'Authorization': `Bearer ${witToken}`,
      'Content-Type': 'audio/wav'
    }
  }, parseResult))
 
setTimeout(() => {
  recording.stop()
}, 3000) // Stop after three seconds of recording

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