| Index: LayoutTests/webaudio/osc-low-freq.html
|
| diff --git a/LayoutTests/webaudio/osc-low-freq.html b/LayoutTests/webaudio/osc-low-freq.html
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..de25c3b270b4eb890d7741ff4ae254f0eb237728
|
| --- /dev/null
|
| +++ b/LayoutTests/webaudio/osc-low-freq.html
|
| @@ -0,0 +1,87 @@
|
| +<!doctype html>
|
| +<html>
|
| + <head>
|
| + <title>Test Custom Oscillator at Very Low Frequency</title>
|
| + <script src="../resources/js-test.js"></script>
|
| + <script src="resources/compatibility.js"></script>
|
| + <script src="resources/audio-testing.js"></script>
|
| + </head>
|
| +
|
| + <body>
|
| + <script>
|
| + description("Test Custom Oscillator at Very Low Frequency");
|
| + window.jsTestIsAsync = true;
|
| +
|
| + // Create a custom oscillator and verify that the parts of a periodic wave that should be
|
| + // ignored really are ignored.
|
| +
|
| + var sampleRate = 48000;
|
| +
|
| + // The desired frequency of the oscillator. The value to be used depends on the
|
| + // implementation of the PeriodicWave and should be less than then lowest fundamental
|
| + // frequency. The lowest frequency is the Nyquist frequency divided by the max number of
|
| + // coefficients used for the FFT. In the current implementation, the max number of
|
| + // coefficients is 2048 (for a sample rate of 48 kHz) so the lowest frequency is 24000/2048 =
|
| + // 11.78 Hz.
|
| + var desiredFrequencyHz = 1;
|
| +
|
| + // Minimum allowed SNR between the actual oscillator and the expected result. Experimentally
|
| + // determined.
|
| + var snrThreshold = 130;
|
| +
|
| + var context;
|
| + var osc;
|
| + var actual;
|
| +
|
| + var audit = Audit.createTaskRunner();
|
| +
|
| + // Compute the SNR between the actual result and expected cosine wave
|
| + function checkCosineResult(result, freq, sampleRate) {
|
| + var signal = 0;
|
| + var noise = 0;
|
| + var omega = 2 * Math.PI * freq / sampleRate;
|
| +
|
| + actual = result.getChannelData(0);
|
| +
|
| + for (var k = 0; k < actual.length; ++k) {
|
| + var x = Math.cos(omega * k);
|
| + var diff = x - actual[k];
|
| + signal += x * x;
|
| + noise += diff * diff;
|
| + }
|
| +
|
| + var snr = 10 * Math.log10(signal / noise);
|
| +
|
| + Should("SNR of " + desiredFrequencyHz + " Hz sine wave", snr).beGreaterThanOrEqualTo(snrThreshold);
|
| + testPassed("PeriodicWave coefficients that must be ignored were correctly ignored.");
|
| + }
|
| +
|
| + function runTest() {
|
| + context = new OfflineAudioContext(1, sampleRate, sampleRate);
|
| + osc = context.createOscillator();
|
| +
|
| + // Create the custom oscillator. For simplicity of testing, we use just a cosine wave, but
|
| + // the initial elements of the real and imaginary parts are explicitly set to non-zero to
|
| + // test that they are ignored.
|
| + var r = new Float32Array(2);
|
| + var i = new Float32Array(2);
|
| + r[0] = 1; // DC component to be ignored
|
| + r[1] = 1; // Fundamental
|
| + i[0] = 1; // Sine term that doesn't actually exist in a Fourier series
|
| + i[1] = 0;
|
| + var wave = context.createPeriodicWave(r, i);
|
| +
|
| + osc.setPeriodicWave(wave);
|
| + osc.frequency.value = desiredFrequencyHz;
|
| + osc.connect(context.destination);
|
| + osc.start();
|
| + context.startRendering().then(function (buffer) {
|
| + checkCosineResult(buffer, desiredFrequencyHz, sampleRate);
|
| + }).then(finishJSTest);
|
| + };
|
| +
|
| + runTest();
|
| + successfullyParsed = true;
|
| + </script>
|
| + </body>
|
| +</html>
|
|
|
Chromium Code Reviews
Issue 1180613007:
Allow larger arrays up to size 8192 for PeriodicWave (Closed)
Base URL: svn://svn.chromium.org/blink/trunk