<!DOCTYPE HTML> <html> <head> <meta charset="utf-8"> <title>Test DynamicsCompressor with Gain</title> <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script> <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" /> </head> <body> <script class="testbody" type="text/javascript"> SimpleTest.waitForExplicitFinish(); addLoadEvent(function() { var samplerate = 44100; var context = new OfflineAudioContext(1, samplerate/100, samplerate); var osc = context.createOscillator(); osc.frequency.value = 2400; var gain = context.createGain(); gain.gain.value = 1.5; // These numbers are borrowed from the example code on MDN // https://developer.mozilla.org/en-US/docs/Web/API/DynamicsCompressorNode var compressor = context.createDynamicsCompressor(); compressor.threshold.value = -50; compressor.knee.value = 40; compressor.ratio.value = 12; compressor.reduction.value = -20; compressor.attack.value = 0; compressor.release.value = 0.25; osc.connect(gain); gain.connect(compressor); compressor.connect(context.destination); osc.start(); context.startRendering().then(buffer => { var peak = Math.max(...buffer.getChannelData(0)); console.log(peak); // These values are experimentally determined. Without dynamics compression // the peak should be just under 1.5. We also check for a minimum value // to make sure we are not getting all zeros. ok(peak >= 0.2 && peak < 1.0, "Peak value should be greater than 0.25 and less than 1.0"); SimpleTest.finish(); }); }); </script> <pre> </pre> </body>