wave-recorder

Pipe Web Audio API nodes into PCM Wave files.

Install

$ npm install wave-recorder

API

var WaveRecorder = require('wave-recorder')

var recorder = WaveRecorder(options)

Returns a stream. Pipe the stream to a file (you can use web-fs or something similar).

options:

• channels: (defaults to 2)
• bitDepth: can be 16 or 32 (defaults to 32)
• silenceDuration: (optional) Specify the maximum duration (in seconds) of silence to record before pausing. Disabled if 0.

recorder.input (AudioNode)

Connect the audio you want to record to this node.

recorder.on('header', func)

Called on every write with a new header containing an updated file length. You can write this to the start of the file, or ignore (most decoders can handle it, just the duration may appear incorrect).

Example

var WaveRecorder = require('wave-recorder')
var WebFS = require('web-fs')

navigator.webkitPersistentStorage.requestQuota(1024*1024, function(grantedBytes) {
  window.webkitRequestFileSystem(PERSISTENT, grantedBytes, onInit)
})

function onInit(fileSystem){
  var fs = WebFS(fileSystem.root)
  var audioContext = new AudioContext()

  navigator.webkitGetUserMedia({audio:true}, function(stream) {
    
    // get the mic input
    var audioInput = audioContext.createMediaStreamSource(stream)

    // create the recorder instance
    var recorder = WaveRecorder(audioContext, {
      channels: 2,
      bitDepth: 32
    })

    audioInput.connect(recorder.input)

    var filePath = 'test.wav'
    var fileStream = fs.createWriteStream(filePath)
    recorder.pipe(fileStream)

    // optionally go back and rewrite header with updated length
    recorder.on('header', function(header){ 
      var headerStream = fs.createWriteStream(path, {
        start: 0,
        flags: 'r+'
      })

      headerStream.write(header)
      headerStream.end()
    })

    // record for 10 seconds then stop
    setTimeout(function(){
      recorder.end()
    }, 10000)
  })
}