<!doctype html>
<html>
<head>
<title>Test Biquad Tail-Time</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>
<script src="../resources/biquad-filters.js"></script>
<script src="test-tail-time.js"></script>
</head>
<body>
<script>
let audit = Audit.createTaskRunner();
let sampleRate = 16384;
let renderSeconds = 1;
let renderFrames = renderSeconds * sampleRate;
// For a highshelf filter:
// b0 = A*[(A+1)+(A−1)*cos(w0)+2*as*sqrt(A)]
// b1 = 2*A*[(A-1)+(A+1)*cos(w0)]
// b2 = A*[(A+1)+(A−1)*cos(w0)-2*as*sqrt(A)]
// a0 = (A+1)-(A-1)*cos(w0)+2*as*sqrt(A)
// a1 = -2*[(A-1)-(A+1)*cos(w0)]
// a2 = (A+1)-(A-1)*cos(w0)-2*as*sqrt(A)
//
// where as = sin(w0)/sqrt(2), w0 = 2*%pi*f0/Fs, and A = 10^(G/40)
//
// The poles of this filter are
//
// -a2/(2*a0) +/- sqrt(a1^2-4*a0*a2)/(2*a0).
//
// Thus, the poles depend on the sign of d = a1^2-4*a0*a2 =
// 16*A*(as^2-sin(w0)^2) = -8*A*sin(w0)^2. Thus, the poles are always
// complex except if w0 = 0, in which case there is a repeated pole at 0.
// Array of tests to run. |descripton| is the task description for
// audit.define. |parameters| is option for |testTailTime|.
let tests = [
{
descripton:
{label: 'highshelf-complex-roots', description: 'complex roots'},
parameters: {
prefix: 'Highshelf complex roots',
filterOptions:
{type: 'highshelf', gain: 40, frequency: sampleRate / 8},
// Node computed tail frame is 18.6 frames, which matches the actual
// tail, so tail output should be exactly zero.
threshold: 0
}
},
{
descripton: {
label: 'highshelf-repeated-roots',
description: 'repeated real root'
},
parameters: {
prefix: 'Highshelf repeated roots',
filterOptions: {type: 'highshelf', gain: 40, frequency: 0},
// Node computed tail frame is 2 frames, which matches the actual
// tail, so tail output should be exactly zero.
threshold: 0
}
},
];
// Define an appropriate task for each test.
tests.forEach(entry => {
audit.define(entry.descripton, (task, should) => {
let context = new OfflineAudioContext(1, renderFrames, sampleRate);
testTailTime(should, context, entry.parameters)
.then(() => task.done());
});
});
audit.run();
</script>
</body>
</html>