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<head>
<title>
Test Basic Oscillator Sine Wave Test
</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>
// Don't change the sample rate. The tests below depend on this sample
// rate to cover all the cases in Chrome's implementation. But the tests
// are general and apply to any browser.
const sampleRate = 44100;
// Only need a few samples for testing, so just use two renders.
const durationFrames = 2 * RENDER_QUANTUM_FRAMES;
let audit = Audit.createTaskRunner();
// The following tests verify that the oscillator produces the same
// results as the mathematical oscillators. We choose sine wave and a
// custom wave because we know they're bandlimited and won't change with
// the frequency.
//
// The tests for 1 and 2 Hz are intended to test Chrome's interpolation
// algorithm, but are still generally applicable to any browser.
audit.define(
{label: 'Test 0', description: 'Sine wave: 100 Hz'},
async (task, should) => {
let context = new OfflineAudioContext(
{length: durationFrames, sampleRate: sampleRate});
const freqHz = 100;
let src =
new OscillatorNode(context, {type: 'sine', frequency: freqHz});
src.connect(context.destination);
src.start();
let renderedBuffer = await context.startRendering();
checkResult(should, renderedBuffer, context, {
freqHz: freqHz,
a1: 0,
b1: 1,
prefix: 'Sine',
threshold: 1.8045e-5,
snrThreshold: 112.5
});
task.done();
});
audit.define(
{label: 'Test 1', description: 'Sine wave: -100 Hz'},
async (task, should) => {
let context = new OfflineAudioContext(
{length: durationFrames, sampleRate: sampleRate});
const freqHz = -100;
let src =
new OscillatorNode(context, {type: 'sine', frequency: freqHz});
src.connect(context.destination);
src.start();
let renderedBuffer = await context.startRendering();
checkResult(should, renderedBuffer, context, {
freqHz: freqHz,
a1: 0,
b1: 1,
prefix: 'Sine',
threshold: 1.8045e-5,
snrThreshold: 112.67
});
task.done();
});
audit.define(
{label: 'Test 2', description: 'Sine wave: 2 Hz'},
async (task, should) => {
let context = new OfflineAudioContext(
{length: durationFrames, sampleRate: sampleRate});
const freqHz = 2;
let src =
new OscillatorNode(context, {type: 'sine', frequency: freqHz});
src.connect(context.destination);
src.start();
let renderedBuffer = await context.startRendering();
checkResult(should, renderedBuffer, context, {
freqHz: freqHz,
a1: 0,
b1: 1,
prefix: 'Sine',
threshold: 1.4516e-7,
snrThreshold: 119.93
});
task.done();
});
audit.define(
{label: 'Test 3', description: 'Sine wave: 1 Hz'},
async (task, should) => {
let context = new OfflineAudioContext(
{length: durationFrames, sampleRate: sampleRate});
const freqHz = 1;
let src =
new OscillatorNode(context, {type: 'sine', frequency: freqHz});
src.connect(context.destination);
src.start();
let renderedBuffer = await context.startRendering();
checkResult(should, renderedBuffer, context, {
freqHz: freqHz,
a1: 0,
b1: 1,
prefix: 'Sine',
threshold: 1.4157e-7,
snrThreshold: 112.22
});
task.done();
});
audit.define(
{label: 'Test 4', description: 'Custom wave: 100 Hz'},
async (task, should) => {
let context = new OfflineAudioContext(
{length: durationFrames, sampleRate: sampleRate});
const freqHz = 100;
let wave = new PeriodicWave(
context,
{real: [0, 1], imag: [0, 1], disableNormalization: true});
let src = new OscillatorNode(
context,
{type: 'custom', frequency: freqHz, periodicWave: wave});
src.connect(context.destination);
src.start();
let renderedBuffer = await context.startRendering();
checkResult(should, renderedBuffer, context, {
freqHz: freqHz,
a1: 1,
b1: 1,
prefix: 'Custom',
threshold: 5.1e-5,
snrThreshold: 112.6
});
task.done();
});
audit.define(
{label: 'Test 5', description: 'Custom wave: 1 Hz'},
async (task, should) => {
let context = new OfflineAudioContext(
{length: durationFrames, sampleRate: sampleRate});
const freqHz = 1;
let wave = new PeriodicWave(
context,
{real: [0, 1], imag: [0, 1], disableNormalization: true});
let src = new OscillatorNode(
context,
{type: 'custom', frequency: freqHz, periodicWave: wave});
src.connect(context.destination);
src.start();
let renderedBuffer = await context.startRendering();
checkResult(should, renderedBuffer, context, {
freqHz: freqHz,
a1: 1,
b1: 1,
prefix: 'Custom',
threshold: 4.7684e-7,
snrThreshold: 133.0
});
task.done();
});
audit.run();
function waveForm(context, freqHz, a1, b1, nsamples) {
let buffer =
new AudioBuffer({length: nsamples, sampleRate: context.sampleRate});
let signal = buffer.getChannelData(0);
const omega = 2 * Math.PI * freqHz / context.sampleRate;
for (let k = 0; k < nsamples; ++k) {
signal[k] = a1 * Math.cos(omega * k) + b1 * Math.sin(omega * k);
}
return buffer;
}
function checkResult(should, renderedBuffer, context, options) {
let {freqHz, a1, b1, prefix, threshold, snrThreshold} = options;
let actual = renderedBuffer.getChannelData(0);
let expected =
waveForm(context, freqHz, a1, b1, actual.length).getChannelData(0);
should(actual, `${prefix}: ${freqHz} Hz`).beCloseToArray(expected, {
absoluteThreshold: threshold
});
let snr = 10 * Math.log10(computeSNR(actual, expected));
should(snr, `${prefix}: SNR (db)`).beGreaterThanOrEqualTo(snrThreshold);
}
</script>
</body>
</html>
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