--- /dev/null
+<!DOCTYPE html>
+
+<html>
+<head>
+<link rel="stylesheet" href="../fast/js/resources/js-test-style.css"/>
+<script src="../fast/js/resources/js-test-pre.js"></script>
+<script type="text/javascript" src="resources/audio-testing.js"></script>
+<script type="text/javascript" src="resources/buffer-loader.js"></script>
+</head>
+
+<body>
+
+<div id="description"></div>
+<div id="console"></div>
+
+<script>
+description("Tests that WaveShaperNode applies proper non-linear distortion.");
+
+var sampleRate = 44100;
+var lengthInSeconds = 4;
+var numberOfRenderFrames = sampleRate * lengthInSeconds;
+var numberOfCurveFrames = 65536;
+var inputBuffer;
+var waveShapingCurve;
+
+var context;
+
+function generateInputBuffer() {
+ // Create mono input buffer.
+ var buffer = context.createBuffer(1, numberOfRenderFrames, context.sampleRate);
+ var data = buffer.getChannelData(0);
+
+ // Generate an input vector with values from -1 -> +1 over a duration of lengthInSeconds.
+ // This exercises the full nominal input range and will touch every point of the shaping curve.
+ for (var i = 0; i < numberOfRenderFrames; ++i) {
+ var x = i / numberOfRenderFrames; // 0 -> 1
+ x = 2 * x - 1; // -1 -> +1
+ data[i] = x;
+ }
+
+ return buffer;
+}
+
+// Generates a symmetric curve: Math.atan(5 * x) / (0.5 * Math.PI)
+// (with x == 0 corresponding to the center of the array)
+// This curve is arbitrary, but would be useful in the real-world.
+// To some extent, the actual curve we choose is not important in this test,
+// since the input vector walks through all possible curve values.
+function generateWaveShapingCurve() {
+ var curve = new Float32Array(numberOfCurveFrames);
+
+ var n = numberOfCurveFrames;
+ var n2 = n / 2;
+
+ for (var i = 0; i < n; ++i) {
+ var x = (i - n2) / n2;
+ var y = Math.atan(5 * x) / (0.5 * Math.PI);
+ }
+
+ return curve;
+}
+
+function checkShapedCurve(event) {
+ var buffer = event.renderedBuffer;
+
+ var inputData = inputBuffer.getChannelData(0);
+ var outputData = buffer.getChannelData(0);
+
+ var success = true;
+
+ // Go through every sample and make sure it has been shaped exactly according to the shaping curve we gave it.
+ for (var i = 0; i < buffer.length; ++i) {
+ var input = inputData[i];
+
+ // Calculate an index based on input -1 -> +1 with 0 being at the center of the curve data.
+ var index = Math.floor(numberOfCurveFrames * 0.5 * (input + 1));
+
+ // Clip index to the input range of the curve.
+ // This takes care of input outside of nominal range -1 -> +1
+ index = index < 0 ? 0 : index;
+ index = index > numberOfCurveFrames - 1 ? numberOfCurveFrames - 1 : index;
+
+ var expectedOutput = waveShapingCurve[index];
+
+ var output = outputData[i];
+
+ if (output != expectedOutput) {
+ success = false;
+ break;
+ }
+ }
+
+ if (success) {
+ testPassed("WaveShaperNode properly applied non-linear distortion.");
+ } else {
+ testFailed("WaveShaperNode did not properly apply non-linear distortion.");
+ }
+
+ finishJSTest();
+}
+
+function runTest() {
+ if (window.layoutTestController) {
+ layoutTestController.dumpAsText();
+ layoutTestController.waitUntilDone();
+ }
+
+ window.jsTestIsAsync = true;
+
+ // Create offline audio context.
+ context = new webkitAudioContext(1, numberOfRenderFrames, sampleRate);
+
+ // source -> waveshaper -> destination
+ var source = context.createBufferSource();
+ var waveshaper = context.createWaveShaper();
+ source.connect(waveshaper);
+ waveshaper.connect(context.destination);
+
+ // Create an input test vector.
+ inputBuffer = generateInputBuffer();
+ source.buffer = inputBuffer;
+
+ // We'll apply non-linear distortion according to this shaping curve.
+ waveShapingCurve = generateWaveShapingCurve();
+ waveshaper.curve = waveShapingCurve;
+
+ source.noteOn(0);
+
+ context.oncomplete = checkShapedCurve;
+ context.startRendering();
+}
+
+runTest();
+successfullyParsed = true;
+
+</script>
+
+<script src="../fast/js/resources/js-test-post.js"></script>
+</body>
+</html>