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 /*   Inverted Waveform Cancellation   Using the Mozilla Audio Data API   by F1LT3R @ http://Bocoup.com */  // This example is illustrative and not enhanced for performance ..."

2011-02-08T06:42:31Z

Created page with "<pre> ‎Inverted Waveform Cancellation Using the Mozilla Audio Data API by F1LT3R @ http://Bocoup.com: // This example is illustrative and not enhanced for performance ..."

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<pre>
/*
Inverted Waveform Cancellation
Using the Mozilla Audio Data API
by F1LT3R @ http://Bocoup.com
*/

// This example is illustrative and not enhanced for performance

// Define event in global/"window" scope
var audioAvailable;

// When the DOM has loaded...
function init(){

// Variable declarations
var inputSamples, outputSamples, chan1, chan2, i, len,
output = document.createElement('audio'),
debug = document.getElementById('debug'),
inverted = 1;

// Toggle inversion on Channel 2
document.getElementById('invertCheckbox').addEventListener('click', function(){ inverted*=-1; },false);

// Initiate the
output.mozSetup(2, 44100, 1);

// WHEN SOUND HAPPENS.........>
audioAvailable = function audioAvailable(event){

// Alias buffer samples to a more conveinient name
inputSamples = event.frameBuffer;

// Set new length and clear channel data
var len = inputSamples.length, chan1 = [], chan2 = [], outputSamples = [];

// Copy Audio-Data from <audio> input to Channel 1 into a Native JS Array
for(i=0;i < len; i++){
chan1[i]= inputSamples[i];
}

// Copy inverted Audio-Data from <audio> input to Channel 2 into a Native JS Array
for(i=0;i < len; i++){
chan2[i] = inputSamples[i]*-inverted;
}

// Mix down Channel 1 and Channel 2
for(i=0;i < len; i++){
outputSamples[i] = (chan1[i] + chan2[i]) / 2;
}

// Display 5 samples from each buffer-written-(event at C level)
debug.innerHTML = "";
for(i=0;i<5;i++){
debug.innerHTML += "<b>"+event.time.toFixed(2) + ":</b>  "+ outputSamples[i]+"<br>";
}

// Output mixed samples to <audio> element
output.mozWriteAudio(outputSamples);

};

var input = document.getElementById('input');
input.volume = 0;
input.addEventListener("MozAudioAvailable", audioAvailable, false);

//.addEventListener('mozAudioAvailable', function(){ mozAudioAvailable(event) }, false);
};

// Call ready event when DOM is loaded
addEventListener('DOMContentLoaded', function(){init();}, false);
</pre>

Inverted-waveform-cancellation.js - Revision history

Admin: Created page with "
/* Inverted Waveform Cancellation Using the Mozilla Audio Data API by F1LT3R @ http://Bocoup.com */ // This example is illustrative and not enhanced for performance ..."