angularchobo angularchobo - 2 months ago 67
Node.js Question

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>

Answer

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);