Created
November 16, 2021 14:51
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Hooking up WebAudio Analyser
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta http-equiv="X-UA-Compatible" content="IE=edge"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1"> | |
| <script src="/~watch.js"></script> | |
| </head> | |
| <body> | |
| <audio id="sourceElement" controls> | |
| <source src="music.mp3" type="audio/mpeg"> | |
| </audio> | |
| <br> | |
| <canvas id="timeElement" style="border: 1px solid #000"></canvas> | |
| <br> | |
| <canvas id="freqElement" style="border: 1px solid #000"></canvas> | |
| <script> | |
| let audioContext = new window.AudioContext(); | |
| let source = audioContext.createMediaElementSource(sourceElement); | |
| sourceElement.onplay = function() { | |
| audioContext.resume(); | |
| } | |
| let analyser = audioContext.createAnalyser(); | |
| source.connect(analyser); | |
| analyser.connect(audioContext.destination); | |
| let timeCanvas = timeElement.getContext("2d"); | |
| let timeDomain = new Uint8Array(analyser.frequencyBinCount); | |
| let freqCanvas = freqElement.getContext("2d"); | |
| let freqDomain = new Uint8Array(analyser.frequencyBinCount); | |
| setInterval(function() { | |
| var w = timeElement.clientWidth; | |
| var bw = Math.ceil(w / analyser.frequencyBinCount); | |
| var h = timeElement.clientHeight; | |
| analyser.getByteTimeDomainData(timeDomain); | |
| timeCanvas.clearRect(0, 0, w, h); | |
| for(var i = 0; i < analyser.frequencyBinCount; i++) { | |
| var bin = timeDomain[i]; | |
| timeCanvas.fillRect(i * bw, 0, bw, h * bin / 255); | |
| } | |
| var w = freqElement.clientWidth; | |
| var bw = Math.ceil(w / analyser.frequencyBinCount); | |
| var h = freqElement.clientHeight; | |
| analyser.getByteFrequencyData(freqDomain); | |
| freqCanvas.clearRect(0, 0, w, h); | |
| for(var i = 0; i < analyser.frequencyBinCount; i++) { | |
| var bin = freqDomain[i]; | |
| freqCanvas.fillRect(i * bw, 0, bw, h * bin / 255); | |
| } | |
| }, 15) | |
| </script> | |
| </body> | |
| </html> |
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