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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /webaudio/the-audio-api/the-constantsourcenode-interface/constant-source-output.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<html>
<head>
<title>
Test ConstantSourceNode Output
</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/audioparam-testing.js"></script>
</head>
<body>
<script id="layout-test-code">
let sampleRate = 48000;
let renderDuration = 0.125;
let renderFrames = sampleRate * renderDuration;
let audit = Audit.createTaskRunner();
audit.define('constant source', (task, should) => {
// Verify a constant source outputs the correct (fixed) constant.
let context = new OfflineAudioContext(1, renderFrames, sampleRate);
let node = new ConstantSourceNode(context, {offset: 0.5});
node.connect(context.destination);
node.start();
context.startRendering()
.then(function(buffer) {
let actual = buffer.getChannelData(0);
let expected = new Float32Array(actual.length);
expected.fill(node.offset.value);
should(actual, 'Basic: ConstantSourceNode({offset: 0.5})')
.beEqualToArray(expected);
})
.then(() => task.done());
});
audit.define('stop before start', (task, should) => {
let context = new OfflineAudioContext(1, renderFrames, sampleRate);
let node = new ConstantSourceNode(context, {offset: 1});
node.connect(context.destination);
node.start(61 / context.sampleRate);
node.stop(31 / context.sampleRate);
context.startRendering()
.then(function(buffer) {
let actual = buffer.getChannelData(0);
should(actual,
"ConstantSourceNode with stop before " +
"start must output silence")
.beConstantValueOf(0);
})
.then(() => task.done());
});
audit.define('stop equal to start', (task, should) => {
let context = new OfflineAudioContext(1, renderFrames, sampleRate);
let node = new ConstantSourceNode(context, {offset: 1});
node.connect(context.destination);
node.start(31 / context.sampleRate);
node.stop(31 / context.sampleRate);
context.startRendering()
.then(function(buffer) {
let actual = buffer.getChannelData(0);
should(actual,
"ConstantSourceNode with stop equal to start " +
" must output silence")
.beConstantValueOf(0);
})
.then(() => task.done());
});
audit.define('start/stop', (task, should) => {
// Verify a constant source starts and stops at the correct time and has
// the correct (fixed) value.
let context = new OfflineAudioContext(1, renderFrames, sampleRate);
let node = new ConstantSourceNode(context, {offset: 1});
node.connect(context.destination);
let startFrame = 10;
let stopFrame = 300;
node.start(startFrame / context.sampleRate);
node.stop(stopFrame / context.sampleRate);
context.startRendering()
.then(function(buffer) {
let actual = buffer.getChannelData(0);
let expected = new Float32Array(actual.length);
// The expected output is all 1s from start to stop time.
expected.fill(0);
for (let k = startFrame; k < stopFrame; ++k) {
expected[k] = node.offset.value;
}
let prefix = 'start/stop: ';
should(actual.slice(0, startFrame),
prefix + 'ConstantSourceNode frames [0, ' +
startFrame + ')')
.beConstantValueOf(0);
should(actual.slice(startFrame, stopFrame),
prefix + 'ConstantSourceNode frames [' +
startFrame + ', ' + stopFrame + ')')
.beConstantValueOf(1);
should(
actual.slice(stopFrame),
prefix + 'ConstantSourceNode frames [' + stopFrame +
', ' + renderFrames + ')')
.beConstantValueOf(0);
})
.then(() => task.done());
});
audit.define('basic automation', (task, should) => {
// Verify that automation works as expected.
let context = new OfflineAudioContext(1, renderFrames, sampleRate);
let source = context.createConstantSource();
source.connect(context.destination);
let rampEndTime = renderDuration / 2;
source.offset.setValueAtTime(0.5, 0);
source.offset.linearRampToValueAtTime(1, rampEndTime);
source.start();
context.startRendering()
.then(function(buffer) {
let actual = buffer.getChannelData(0);
let expected = createLinearRampArray(
0, rampEndTime, 0.5, 1, context.sampleRate);
let rampEndFrame = Math.ceil(rampEndTime * context.sampleRate);
let prefix = 'Automation: ';
should(actual.slice(0, rampEndFrame),
prefix + 'ConstantSourceNode.linearRamp(1, 0.5)')
.beCloseToArray(expected, {
// Experimentally determined threshold.
relativeThreshold: 7.1610e-7
});
should(actual.slice(rampEndFrame),
prefix + 'ConstantSourceNode after ramp')
.beConstantValueOf(1);
})
.then(() => task.done());
});
audit.define('connected audioparam', (task, should) => {
// Verify the constant source output with connected AudioParam produces
// the correct output.
let context = new OfflineAudioContext(2, renderFrames, sampleRate)
context.destination.channelInterpretation = 'discrete';
let source = new ConstantSourceNode(context, {offset: 1});
let osc = context.createOscillator();
let merger = context.createChannelMerger(2);
merger.connect(context.destination);
source.connect(merger, 0, 0);
osc.connect(merger, 0, 1);
osc.connect(source.offset);
osc.start();
let sourceStartFrame = 10;
source.start(sourceStartFrame / context.sampleRate);
context.startRendering()
.then(function(buffer) {
// Channel 0 and 1 should be identical, except channel 0 (the
// source) is silent at the beginning.
let actual = buffer.getChannelData(0);
let expected = buffer.getChannelData(1);
// The expected output should be oscillator + 1 because offset
// is 1.
expected = expected.map(x => 1 + x);
let prefix = 'Connected param: ';
// The initial part of the output should be silent because the
// source node hasn't started yet.
should(
actual.slice(0, sourceStartFrame),
prefix + 'ConstantSourceNode frames [0, ' + sourceStartFrame +
')')
.beConstantValueOf(0);
// The rest of the output should be the same as the oscillator (in
// channel 1)
should(
actual.slice(sourceStartFrame),
prefix + 'ConstantSourceNode frames [' + sourceStartFrame +
', ' + renderFrames + ')')
.beCloseToArray(expected.slice(sourceStartFrame), 0);
})
.then(() => task.done());
});
audit.run();
</script>
</body>
</html>