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<!DOCTYPE html>
<!--
Tests that multiple audio-rate signals (AudioNode outputs) can be connected to an AudioParam
and that these signals are summed, along with the AudioParams intrinsic value.
-->
<html>
<head>
<title>
audioparam-summingjunction.html
</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>
<script src="/webaudio/resources/mix-testing.js"></script>
</head>
<body>
<script id="layout-test-code">
let audit = Audit.createTaskRunner();
let sampleRate = 44100.0;
let lengthInSeconds = 1;
let context = 0;
// Buffers used by the two gain controlling sources.
let linearRampBuffer;
let toneBuffer;
let toneFrequency = 440;
// Arbitrary non-zero value.
let baselineGain = 5;
// Allow for a small round-off error.
let maxAllowedError = 1e-6;
function checkResult(renderedBuffer, should) {
let renderedData = renderedBuffer.getChannelData(0);
// Get buffer data from the two sources used to control gain.
let linearRampData = linearRampBuffer.getChannelData(0);
let toneData = toneBuffer.getChannelData(0);
let n = renderedBuffer.length;
should(n, 'Rendered signal length').beEqualTo(linearRampBuffer.length);
// Check that the rendered result exactly matches the sum of the
// intrinsic gain plus the two sources used to control gain. This is
// because we're changing the gain of a signal having constant value 1.
let success = true;
for (let i = 0; i < n; ++i) {
let expectedValue = baselineGain + linearRampData[i] + toneData[i];
let error = Math.abs(expectedValue - renderedData[i]);
if (error > maxAllowedError) {
success = false;
break;
}
}
should(
success,
'Rendered signal matches sum of two audio-rate gain changing signals plus baseline gain')
.beTrue();
}
audit.define('test', function(task, should) {
let sampleFrameLength = sampleRate * lengthInSeconds;
// Create offline audio context.
context = new OfflineAudioContext(1, sampleFrameLength, sampleRate);
// Create buffer used by the source which will have its gain controlled.
let constantOneBuffer =
createConstantBuffer(context, sampleFrameLength, 1);
let constantSource = context.createBufferSource();
constantSource.buffer = constantOneBuffer;
// Create 1st buffer used to control gain (a linear ramp).
linearRampBuffer = createLinearRampBuffer(context, sampleFrameLength);
let gainSource1 = context.createBufferSource();
gainSource1.buffer = linearRampBuffer;
// Create 2st buffer used to control gain (a simple sine wave tone).
toneBuffer =
createToneBuffer(context, toneFrequency, lengthInSeconds, 1);
let gainSource2 = context.createBufferSource();
gainSource2.buffer = toneBuffer;
// Create a gain node controlling the gain of constantSource and make
// the connections.
let gainNode = context.createGain();
// Intrinsic baseline gain.
// This gain value should be summed with gainSource1 and gainSource2.
gainNode.gain.value = baselineGain;
constantSource.connect(gainNode);
gainNode.connect(context.destination);
// Connect two audio-rate signals to control the .gain AudioParam.
gainSource1.connect(gainNode.gain);
gainSource2.connect(gainNode.gain);
// Start all sources at time 0.
constantSource.start(0);
gainSource1.start(0);
gainSource2.start(0);
context.startRendering().then(buffer => {
checkResult(buffer, should);
task.done();
});
});
audit.run();
</script>
</body>
</html>
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