84 lines
2.9 KiB
HTML
84 lines
2.9 KiB
HTML
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<!doctype html>
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<html>
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<head>
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<title>Test Biquad Tail-Time</title>
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<script src="../../imported/w3c/web-platform-tests/resources/testharness.js"></script>
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<script src="../../resources/testharnessreport.js"></script>
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<script src="../resources/audit-util.js"></script>
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<script src="../resources/audit.js"></script>
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<script src="../resources/biquad-filters.js"></script>
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<script src="test-tail-time.js"></script>
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</head>
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<body>
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<script>
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let audit = Audit.createTaskRunner();
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let sampleRate = 16384;
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let renderSeconds = 1;
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let renderFrames = renderSeconds * sampleRate;
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let renderQuantumFrames = 128;
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// For a lowshelf filter:
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// b0 = A*[(A+1)−(A−1)*cos(w0)+2*as*sqrt(A)]
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// b1 = 2*A*[(A+1)-(A-1)*cos(w0)]
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// b2 = A*[(A+1)−(A−1)*cos(w0)-2*as*sqrt(A)]
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// a0 = (A+1)+(A-1)*cos(w0)+2*as*sqrt(A)
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// a1 = -2*[(A-1)+(A+1)*cos(w0)]
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// a2 = (A+1)+(A-1)*cos(w0)-2*as*sqrt(A)
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//
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// where as = sin(w0)/sqrt(2), w0 = 2*%pi*f0/Fs, and A = 10^(G/40)
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//
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// The poles of this filter are
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//
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// -a2/(2*a0) +/- sqrt(a1^2-4*a0*a2)/(2*a0).
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//
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// Thus, the poles depend on the sign of d = a1^2-4*a0*a2 =
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// 16*A*(as^2-sin(w0)^2) = -8*A*sin(w0)^2. Thus, the poles are always
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// complex except if w0 = 0, in which case there is a repeated pole at 0.
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// Array of tests to run. |descripton| is the task description for
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// audit.define. |parameters| is option for |testTailTime|.
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let tests = [
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{
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descripton:
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{label: 'lowshelf-complex-roots', description: 'complex roots'},
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parameters: {
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prefix: 'Lowshelf complex roots',
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filterOptions:
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{type: 'lowshelf', gain: 40, frequency: sampleRate / 8},
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// Node computed tail frame is 75.5 frames, which matches the actual
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// tail, so tail output should be exactly zero.
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threshold: 0
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},
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},
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{
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descripton: {
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label: 'lowshelf-repeated-roots',
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description: 'repeated real root'
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},
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parameters: {
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prefix: 'Lowshelf repeated roots',
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filterOptions:
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{type: 'lowshelf', Q: 1 / 20, gain: 40, frequency: 0},
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// Node computed tail frame is 2 frames, which matches the actual
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// tail, so tail output should be exactly zero.
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threshold: 0
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},
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},
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];
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// Define an appropriate task for each test.
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tests.forEach(entry => {
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audit.define(entry.descripton, (task, should) => {
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let context = new OfflineAudioContext(1, renderFrames, sampleRate);
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testTailTime(should, context, entry.parameters)
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.then(() => task.done());
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});
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});
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audit.run();
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</script>
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</body>
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</html>
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