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<!DOCTYPE html>
<html>
<head>
<title>
Test Biquad Tail Output
</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/webaudio/resources/audit-util.js"></script>
<script src="/webaudio/resources/audit.js"></script>
</head>
<body>
<script id="layout-test-code">
let audit = Audit.createTaskRunner();
// A high sample rate shows the issue more clearly.
let sampleRate = 192000;
// Some short duration because we don't need to run the test for very
// long.
let testDurationSec = 0.5;
let testDurationFrames = testDurationSec * sampleRate;
// Amplitude experimentally determined to give a biquad output close to 1.
// (No attempt was made to produce exactly 1; it's not needed.)
let sourceAmplitude = 100;
// The output of the biquad filter should not change by more than this
// much between output samples. Threshold was determined experimentally.
let glitchThreshold = 0.012968;
// Test that a Biquad filter doesn't have it's output terminated because
// the input has gone away. Generally, when a source node is finished, it
// disconnects itself from any downstream nodes. This is the correct
// behavior. Nodes that have no inputs (disconnected) are generally
// assumed to output zeroes. This is also desired behavior. However,
// biquad filters have memory so they should not suddenly output zeroes
// when the input is disconnected. This test checks to see if the output
// doesn't suddenly change to zero.
audit.define(
{label: 'test', description: 'Biquad Tail Output'},
function(task, should) {
let context =
new OfflineAudioContext(1, testDurationFrames, sampleRate);
// Create an impulse source.
let buffer = context.createBuffer(1, 1, context.sampleRate);
buffer.getChannelData(0)[0] = sourceAmplitude;
let source = context.createBufferSource();
source.buffer = buffer;
// Create the biquad filter. It doesn't really matter what kind, so
// the default filter type and parameters is fine. Connect the
// source to it.
let biquad = context.createBiquadFilter();
source.connect(biquad);
biquad.connect(context.destination);
source.start();
context.startRendering().then(function(result) {
// There should be no large discontinuities in the output
should(result.getChannelData(0), 'Biquad output')
.notGlitch(glitchThreshold);
task.done();
})
});
audit.run();
</script>
</body>
</html>
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