| Index: third_party/WebKit/LayoutTests/webaudio/BiquadFilter/tail-time-lowpass.html
|
| diff --git a/third_party/WebKit/LayoutTests/webaudio/BiquadFilter/tail-time-lowpass.html b/third_party/WebKit/LayoutTests/webaudio/BiquadFilter/tail-time-lowpass.html
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..dc0426371a19453512c3f2f28e506d1650390190
|
| --- /dev/null
|
| +++ b/third_party/WebKit/LayoutTests/webaudio/BiquadFilter/tail-time-lowpass.html
|
| @@ -0,0 +1,168 @@
|
| +<!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;
|
| +
|
| + // For a lowpass filter:
|
| + // b0 = (1-cos(w0))/2
|
| + // b1 = 1-cos(w0)
|
| + // b2 = (1-cos(w0))/2
|
| + // a0 = 1 + alpha
|
| + // a1 = -2*cos(w0)
|
| + // a2 = 1 - alpha
|
| + //
|
| + // where alpha = sin(w0)/(2*10^(Q/20)) and w0 = 2*%pi*f0/Fs.
|
| + //
|
| + // Equivalently a1 = -2*cos(w0)/(1+alpha), a2 = (1-alpha)/(1+alpha). The
|
| + // poles of this filter are at
|
| + //
|
| + // cos(w0)/(1+alpha) +/- sqrt(alpha^2-sin(w0)^2)/(1+alpha)
|
| + //
|
| + // But alpha^2-sin(w0)^2 = sin(w0)^2*(1/4/10^(Q/10) - 1). Thus the poles
|
| + // are complex if 1/4/10^(Q/10) < 1; real distinct if 1/4/10^(Q/10) > 1;
|
| + // and repeated if 1/4/10^(Q/10) = 1.
|
| +
|
| + // Array of tests to run. |descripton| is the task description for
|
| + // audit.define. |parameters| is option for |testTailTime|.
|
| + let tests = [
|
| + {
|
| + descripton:
|
| + {label: 'lpf-complex-roots', description: 'complex roots'},
|
| + sampleRate: sampleRate,
|
| + renderDuration: renderSeconds,
|
| + parameters: {
|
| + prefix: 'LPF complex roots',
|
| + filterOptions: {type: 'lowpass', Q: 40, frequency: sampleRate / 4}
|
| + },
|
| + // Node computed tail frame is 2079.4 which matches the real tail, so
|
| + // tail output should be exactly 0.
|
| + threshold: 0,
|
| + },
|
| + {
|
| + descripton: {
|
| + label: 'lpf-real-distinct-roots',
|
| + description: 'real distinct roots'
|
| + },
|
| + sampleRate: sampleRate,
|
| + renderDuration: renderSeconds,
|
| + parameters: {
|
| + prefix: 'LPF real distinct roots',
|
| + filterOptions:
|
| + {type: 'lowpass', Q: -50, frequency: sampleRate / 8}
|
| + },
|
| + // Node computed tail frame is 1699 which matches the real tail, so
|
| + // tail output should be exactly 0.
|
| + threshold: 0,
|
| + },
|
| + {
|
| + descripton:
|
| + {label: 'lpf-repeated-root', description: 'repeated real root'},
|
| + sampleRate: sampleRate,
|
| + renderDuration: renderSeconds,
|
| + parameters: {
|
| + prefix: 'LPF repeated roots (approximately)',
|
| + // For a repeated root, we need 1/4/10^(Q/10) = 1, or Q =
|
| + // -10*log(4)/log(10). This isn't exactly representable as a float,
|
| + // we the roots might not actually be repeated. In fact the roots
|
| + // are actually complex at 6.402396e-5*exp(i*1.570796).
|
| + filterOptions: {
|
| + type: 'lowpass',
|
| + Q: -10 * Math.log10(4),
|
| + frequency: sampleRate / 4
|
| + }
|
| + },
|
| + // Node computed tail frame is 2.9 which matches the real tail, so
|
| + // tail output should be exactly 0.
|
| + threshold: 0,
|
| + },
|
| + {
|
| + descripton: {label: 'lpf-real-roots-2', description: 'complex roots'},
|
| + sampleRate: sampleRate,
|
| + renderDuration: renderSeconds,
|
| + parameters: {
|
| + prefix: 'LPF repeated roots 2',
|
| + // This tests an extreme case where approximate impulse response is
|
| + // h(n) = C*r^(n-1) and C < 1/32768. Thus, the impulse response is
|
| + // always less than the response threshold of 1/32768.
|
| + filterOptions:
|
| + {type: 'lowpass', Q: -100, frequency: sampleRate / 4}
|
| + },
|
| + // Node computed tail frame is 0 which matches the real tail, so
|
| + // tail output should be exactly 0.
|
| + threshold: 0,
|
| + },
|
| + {
|
| + descripton: 'huge tail',
|
| + // The BiquadFilter has an internal maximum tail of 30 sec so we want
|
| + // to render for at least 30 sec to test this. Use the smallest
|
| + // sample rate we can to limit memory and CPU usage!
|
| + sampleRate: 3000,
|
| + renderDuration: 31,
|
| + parameters: {
|
| + prefix: 'LPF repeated roots (approximately)',
|
| + hugeTaileTime: true,
|
| + // For the record, for this lowpass filter, the computed tail time
|
| + // is approximately 2830.23 sec, with poles at
|
| + // 0.999998960442086*exp(i*0.209439510236777). This is very close to
|
| + // being marginally stable.
|
| + filterOptions: {
|
| + type: 'lowpass',
|
| + Q: 100,
|
| + frequency: 100,
|
| + },
|
| + // Node computed tail frame is 8.49069e6 which is clamped to 30 sec
|
| + // so tail output should be exactly 0 after 30 sec.
|
| + threshold: 0,
|
| + },
|
| + },
|
| + {
|
| + descripton: 'ginormous tail',
|
| + // Or this lowpass filter, the complex poles are actually computed to
|
| + // be on the unit circle so the tail infinite. This just tests that
|
| + // nothing bad happens in computing the tail time. Thus, any small
|
| + // sample rate and short duration for the test; the results aren't
|
| + // really interesting. (But they must pass, of course!)
|
| + sampleRate: 3000,
|
| + renderDuration: 0.25,
|
| + parameters: {
|
| + prefix: 'LPF repeated roots (approximately)',
|
| + filterOptions: {
|
| + type: 'lowpass',
|
| + Q: 500,
|
| + frequency: 100,
|
| + },
|
| + },
|
| + // Node computed tail frame is 90000 which matches the real tail, so
|
| + // tail output should be exactly 0.
|
| + threshold: 0,
|
| + }
|
| + ]
|
| +
|
| + // Define an appropriate task for each test.
|
| + tests.forEach(entry => {
|
| + audit.define(entry.descripton, (task, should) => {
|
| + let context = new OfflineAudioContext(
|
| + 1, entry.renderDuration * entry.sampleRate, entry.sampleRate);
|
| + testTailTime(should, context, entry.parameters)
|
| + .then(() => task.done());
|
| + });
|
| + });
|
| +
|
| + audit.run();
|
| + </script>
|
| + </body>
|
| +</html>
|
|
|
Chromium Code Reviews
Issue 2862373002:
Compute tail time from Biquad coefficients (Closed)
