CODEWITHSUNDEEP
javascriptnode.jsaudiobase64node-webkit
angularchobo
angularchobo

Reputation: 313

How to write .wav file from blob in Javascript/Node

I'm trying to write a .wav file with fs.writeFile. The file is created successfully, however it's only 8-13bytes long, so obviously I'm not doing something right.

If the blob is already audio/wav can I write to disk or do I need to convert it to Base 64?

I'm pretty much at a loss here, I found another similar thread with no answer - Here

Any input would be appreciated.

routerApp.controller('audiotest', function($scope) {
 $scope.saveToDisk = function(){
  var nw = require('nw.gui');
  var fs = require('fs');
  var path = require('path');
  fs.writeFileSync('test.wav', $scope.recordedInput)
 };
}

console.log($scope.recordedInput) returns Blob {size: 294956, type: "audio/wav"}

It's not really relevant, but here's my HTML

<div class="row" ng-controller="audiotest">
<div class="row">
    <button type="button" ng-click="saveToDisk()"> Write this sucker to disk </button>
    </div>

<ng-audio-recorder id='audioInput' audio-model='recordedInput'>
  <!-- Start controls, exposed via recorder-->
  <div ng-if="recorder.isAvailable">
    <button ng-click="recorder.startRecord()" type="button" ng-disabled="recorder.status.isRecording">
        Start Record
    </button>
    <button ng-click="recorder.stopRecord()" type="button" ng-disabled="recorder.status.isRecording === false">
        Stop Record
    </button>

</ng-audio-recorder>
</div>

Upvotes: 11

Views: 35187

Answers (3)

rickrizzo
rickrizzo

Reputation: 602

I had issues getting either of these to work for me. I found success, and much easier implementation with this node module express-fileupload. Here's some code:

var express = require('express');
var fileUpload = require('express-fileupload');

app.use(fileUpload());

app.post('/', function(req, res) {


  console.log(req.files.data);
  req.files.data.mv('test.wav', function(err) {
    if (err) {
      console.log(err);
    }
  });
});

Upvotes: 1

Doctor
Doctor

Reputation: 7946

Using mscdex answer.

This is what worked for me when using NodeWebkit as browser.

var fileReader = new FileReader();
fileReader.onload = function () {
       fs.writeFileSync('test.wav', Buffer(new Uint8Array(this.result)));
};
fileReader.readAsArrayBuffer(blob);

Notice the "from" method of Buffer has disappear. And "blob" that is passed in my last line is audio data encoded in wav.
For the rest, its only magic. Don't ask me...

Upvotes: -1

mscdex
mscdex

Reputation: 106698

You can convert the Blob to a Typed Array and then to a Buffer for passing directly to fs.writeFileSync():

var fileReader = new FileReader();
fileReader.onload = function() {
  fs.writeFileSync('test.wav', Buffer.from(new Uint8Array(this.result)));
};
fileReader.readAsArrayBuffer($scope.recordedInput);

Upvotes: 11

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