| <!doctype html> |
| <html> |
| <head> |
| <title>Test Biquad Tail-Time</title> |
| <script src="../../imported/w3c/web-platform-tests/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 highpass 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: 'hpf-complex-roots', description: 'complex roots'}, |
| parameters: { |
| prefix: 'HPF complex roots', |
| filterOptions: {type: 'highpass', Q: 40, frequency: sampleRate / 4}, |
| // Node computed tail frame is 2079.4, which matches the actual tail |
| // frome so output should be exactly 0. |
| threshold: 0 |
| } |
| }, |
| { |
| descripton: { |
| label: 'hpf-real-distinct-roots', |
| description: 'real distinct roots' |
| }, |
| parameters: { |
| prefix: 'HPF real distinct roots', |
| filterOptions: |
| {type: 'highpass', Q: -50, frequency: sampleRate / 8}, |
| // With these filter parameters, the real tail time is 408, but |
| // the node overestimates it to be 2367. Thus, the actual tail |
| // frames won't be exactly zero. |
| threshold: 1 / 32768 |
| } |
| }, |
| { |
| descripton: |
| {label: 'hpf-repeated-root', description: 'repeated real root'}, |
| parameters: { |
| prefix: 'HPF 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, |
| // so the roots might not actually be repeated. In fact the roots |
| // are complex at 6.40239e-5*exp(i*1.570596). |
| filterOptions: { |
| type: 'highpass', |
| Q: -10 * Math.log10(4), |
| frequency: sampleRate / 4 |
| }, |
| // Node computed tail frame is 2.9, which matches the actual tail |
| // frome so output should be exactly 0. |
| threshold: 0 |
| } |
| }, |
| { |
| descripton: {label: 'hpf-real-roots-2', description: 'complex roots'}, |
| parameters: { |
| prefix: 'HPF 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: 'highpass', Q: -100, frequency: sampleRate / 4}, |
| // Node computed tail frame is 0, which matches the actual tail |
| // frame so 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, renderFrames, sampleRate); |
| testTailTime(should, context, entry.parameters) |
| .then(() => task.done()); |
| }); |
| }); |
| |
| audit.run(); |
| </script> |
| </body> |
| </html> |
