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<!DOCTYPE html>
<html>
<head>
<title>
waveshaper-limits.html
</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../../resources/audit-util.js"></script>
<script src="../../resources/audit.js"></script>
</head>
<body>
<script id="layout-test-code">
let audit = Audit.createTaskRunner();
let context;
let bufferData;
let outputData;
let reference;
let sampleRate = 48000;
// Must be odd so we have an exact middle point.
let testFrames = 23;
let scale = 1 / ((testFrames - 1) / 2 - 1);
// Number of decimal digits to print
let decimals = 6;
// Required accuracy
let diffThreshold = Math.pow(10, -decimals);
// Generate reference data
function generateReference() {
// The curve data is 0, 1, 0, and the input data is a ramp from -1+eps
// to 1+eps. Then the output is a ramp from 0 to 1 back to 0.
let ref = new Float32Array(testFrames);
let midPoint = (testFrames - 1) / 2;
// First sample is below -1 at -1-scale.
ref[0] = 0;
// Generate ramp up to the mid-point
for (let k = 0; k < midPoint; ++k) {
ref[k + 1] = k * scale;
}
// The value at the mid-point must be 1, from the curve
ref[midPoint] = 1;
// Generate a ramp from 1 down to 0
for (let k = midPoint; k < testFrames - 1; ++k) {
ref[k + 1] = 2 - k * scale;
}
// The last sample is out of range at 1+scale
ref[testFrames - 1] = 0;
return ref;
}
function checkResult(renderedBuffer, should) {
outputData = renderedBuffer.getChannelData(0);
reference = generateReference();
let success = true;
// Verify that every output value matches our expected reference value.
for (let k = 0; k < outputData.length; ++k) {
let diff = outputData[k] - reference[k];
should(
Math.abs(diff),
'Max error mapping ' + bufferData[k].toFixed(decimals) + ' to ' +
outputData[k].toFixed(decimals))
.beLessThanOrEqualTo(diffThreshold);
}
}
audit.define(
{
label: 'test',
description:
'WaveShaperNode including values outside the range of [-1,1]'
},
function(task, should) {
context = new OfflineAudioContext(1, testFrames, sampleRate);
// Create input values between -1.1 and 1.1
let buffer =
context.createBuffer(1, testFrames, context.sampleRate);
bufferData = new Float32Array(testFrames);
let start = -1 - scale;
for (let k = 0; k < testFrames; ++k) {
bufferData[k] = k * scale + start;
}
buffer.copyToChannel(bufferData, 0);
let source = context.createBufferSource();
source.buffer = buffer;
// Create simple waveshaper. It should map -1 to 0, 0 to 1, and +1
// to 0 and interpolate all points in between using a simple linear
// interpolator.
let shaper = context.createWaveShaper();
let curve = new Float32Array(3);
curve[0] = 0;
curve[1] = 1;
curve[2] = 0;
shaper.curve = curve;
source.connect(shaper);
shaper.connect(context.destination);
source.start();
context.startRendering()
.then(buffer => checkResult(buffer, should))
.then(() => task.done());
});
audit.run();
</script>
</body>
</html>
|
