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https://github.com/daaain/JSSoundRecorder

A simple JavaScript sound recorder and editor
https://github.com/daaain/JSSoundRecorder

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A simple JavaScript sound recorder and editor

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README 

        
JSSoundRecorder

===============



Record sounds / noises around you and turn them into music.



It’s a work in progress, at the moment it enables you to record live audio straight from your browser, edit it and save these sounds as a WAV file.



There's also a sequencer part where you can create small loops using these sounds with a drone synth overlaid on them.



See it working: http://daaain.github.com/JSSoundRecorder



Technology

----------



No servers involved, only Web Audio API with binary sound Blobs passed around!



### Web Audio API



#### GetUserMedia audio for live recording



Experimental API to record any system audio input (including USB soundcards, musical instruments, etc).



```javascript

// shim and create AudioContext

window.AudioContext = window.AudioContext || window.webkitAudioContext || window.mozAudioContext;

var audio_context = new AudioContext();



// shim and start GetUserMedia audio stream

navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia;

navigator.getUserMedia({audio: true}, startUserMedia, function(e) {

  console.log('No live audio input: ' + e);

});

```



#### Audio nodes for routing



You can route audio stream around, with input nodes (microphone, synths, etc), filters (volume / gain, equaliser, low pass, etc) and outputs (speakers, binary streams, etc).



```javascript

function startUserMedia(stream) {

  // create MediaStreamSource and GainNode

  var input = audio_context.createMediaStreamSource(stream);

  var volume = audio_context.createGain();

  volume.gain.value = 0.7;



  // connect them and pipe output

  input.connect(volume);

  volume.connect(audio_context.destination);

  

  // connect recorder as well - see below

  var recorder = new Recorder(input);

}

```



### WebWorker



Processing (interleaving) record buffer is done in the background to not block the main thread and the UI.



Also WAV conversion for export is also quite heavy for longer recordings, so best left to run in the background.



```javascript

this.context = input.context;

this.node = this.context.createScriptProcessor(4096, 2, 2);

this.node.onaudioprocess = function(e){

  worker.postMessage({

   command: 'record',

   buffer: [

     e.inputBuffer.getChannelData(0),

     e.inputBuffer.getChannelData(1)

   ]

  });

}

```



```javascript

function record(inputBuffer){

  var bufferL = inputBuffer[0];

  var bufferR = inputBuffer[1];

  var interleaved = interleave(bufferL, bufferR);

  recBuffers.push(interleaved);

  recLength += interleaved.length;

}



function interleave(inputL, inputR){

  var length = inputL.length + inputR.length;

  var result = new Float32Array(length);



  var index = 0,

      inputIndex = 0;



  while (index < length){

    result[index++] = inputL[inputIndex];

    result[index++] = inputR[inputIndex];

    inputIndex++;

  }

  return result;

}

```



```javascript

function encodeWAV(samples){

  var buffer = new ArrayBuffer(44 + samples.length * 2);

  var view = new DataView(buffer);



  /* RIFF identifier */

  writeString(view, 0, 'RIFF');

  /* file length */

  view.setUint32(4, 32 + samples.length * 2, true);

  /* RIFF type */

  writeString(view, 8, 'WAVE');

  /* format chunk identifier */

  writeString(view, 12, 'fmt ');

  /* format chunk length */

  view.setUint32(16, 16, true);

  /* sample format (raw) */

  view.setUint16(20, 1, true);

  /* channel count */

  view.setUint16(22, 2, true);

  /* sample rate */

  view.setUint32(24, sampleRate, true);

  /* byte rate (sample rate * block align) */

  view.setUint32(28, sampleRate * 4, true);

  /* block align (channel count * bytes per sample) */

  view.setUint16(32, 4, true);

  /* bits per sample */

  view.setUint16(34, 16, true);

  /* data chunk identifier */

  writeString(view, 36, 'data');

  /* data chunk length */

  view.setUint32(40, samples.length * 2, true);



  floatTo16BitPCM(view, 44, samples);



  return view;

}

```



### Binary Blob



Instead of file drag and drop interface this binary blob is passed to editor.



Note: BlobBuilder deprecated (but a lot of examples use it), you should use Blob constructor instead!



```javascript

var f = new FileReader();

f.onload = function(e) {

  audio_context.decodeAudioData(e.target.result, function(buffer) {

      $('#audioLayerControl')[0].handleAudio(buffer);

    }, function(e) {

      console.warn(e);

    });

  };

f.readAsArrayBuffer(blob);

```



```javascript

function exportWAV(type){

  var buffer = mergeBuffers(recBuffers, recLength);

  var dataview = encodeWAV(buffer);

  var audioBlob = new Blob([dataview], { type: type });



  this.postMessage(audioBlob);

}

```



### Virtual File – URL.createObjectURL



You can create file download link pointing to WAV blob, but also set it as the source of an Audio element.



```javascript

var url = URL.createObjectURL(blob);

var audioElement = document.createElement('audio');

var downloadAnchor = document.createElement('a');



audioElement.controls = true;

audioElement.src = url;



downloadAnchor.href = url;

```



TODO

----



* Sequencer top / status row should be radio buttons :)

* Code cleanup / restructuring

* Enable open / drag and drop files for editing

* Visual feedback (levels) for live recording

* Sequencer UI (and separation to a different module)



Credits / license

-----------------



Live recording code adapted from: http://www.phpied.com/files/webaudio/record.html



Editor code adapted from: https://github.com/plucked/html5-audio-editor



Copyright (c) 2012 Daniel Demmel



MIT License



Permission is hereby granted, free of charge, to any person obtaining

a copy of this software and associated documentation files (the

"Software"), to deal in the Software without restriction, including

without limitation the rights to use, copy, modify, merge, publish,

distribute, sublicense, and/or sell copies of the Software, and to

permit persons to whom the Software is furnished to do so, subject to

the following conditions:



The above copyright notice and this permission notice shall be

included in all copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.