Created
January 17, 2014 01:32
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| #meter { | |
| width: 0%; | |
| height: 15px; | |
| margin: 2px 0; | |
| background: green; | |
| -webkit-transition: width .05s; | |
| } |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset=utf-8 /> | |
| <title>JS Bin</title> | |
| </head> | |
| <body> | |
| <div id=meter></div> | |
| </body> | |
| </html> | |
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| +function(){ | |
| console.log('start-----------------------'); | |
| var ctx = new webkitAudioContext() | |
| , url = '//geekwithopinions.com/media/test.mp3' | |
| , audio = new Audio(url) | |
| // 2048 sample buffer, 1 channel in, 1 channel out | |
| , processor = ctx.createJavaScriptNode(2048, 1, 1) | |
| , meter = document.getElementById('meter') | |
| , source | |
| audio.addEventListener('canplaythrough', function(){ | |
| source = ctx.createMediaElementSource(audio) | |
| source.connect(processor) | |
| source.connect(ctx.destination) | |
| processor.connect(ctx.destination) | |
| audio.play() | |
| }, false); | |
| // loop through PCM data and calculate average | |
| // volume for a given 2048 sample buffer | |
| processor.onaudioprocess = function(evt){ | |
| var input = evt.inputBuffer.getChannelData(0) | |
| , len = input.length | |
| , total = i = 0 | |
| , rms | |
| while ( i < len ) total += Math.abs( input[i++] ); | |
| rms = Math.sqrt( total / (len /2)); | |
| meter.style.width = ( rms * 100 ) + '%'; | |
| var decibel = 20 * (Math.log(rms) / Math.log(10)); | |
| //console.log(decibel, rms); | |
| if (decibel < -5 && | |
| decibel != Number.NEGATIVE_INFINITY && | |
| !isShot){ | |
| isShot = true; | |
| console.log('shot started', decibel); | |
| } | |
| if (decibel >= -5 && isShot){ | |
| isShot = false; | |
| console.log('no shot'); | |
| } | |
| } | |
| var isShot = false; | |
| }() |
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