test_delayNodeTailWithDisconnect.html

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<html>

<head>

  <title>Test tail time lifetime of DelayNode after input is disconnected</title>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <script type="text/javascript" src="webaudio.js"></script>

  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />

</head>

<body>

<pre id="test">

<script class="testbody" type="text/javascript">

// Web Audio doesn't provide a means to precisely time disconnect()s but we

// can test that the output of delay nodes matches the output from their

// sources before they are disconnected.

SimpleTest.waitForExplicitFinish();

const signalLength = 128;

const bufferSize = 4096;

const sourceCount = bufferSize / signalLength;

// Delay should be long enough to allow CC to run

var delayBufferCount = 20;

const delayLength = delayBufferCount * bufferSize;

var sourceOutput = new Float32Array(bufferSize);

var delayOutputCount = 0;

var sources = [];

function onDelayOutput(e) {

  if (delayOutputCount < delayBufferCount) {

    delayOutputCount++;

    return;

  compareChannels(e.inputBuffer.getChannelData(0), sourceOutput);

  e.target.onaudioprocess = null;

  SimpleTest.finish();

function onSourceOutput(e) {

  // Record the first buffer

  e.inputBuffer.copyFromChannel(sourceOutput, 0);

  e.target.onaudioprocess = null;

function disconnectSources() {

  for (var i = 0; i < sourceCount; ++i) {

    sources[i].disconnect();

  SpecialPowers.forceGC();

  SpecialPowers.forceCC();

function startTest() {

  var ctx = new AudioContext();

  var sourceProcessor = ctx.createScriptProcessor(bufferSize, 1, 0);

  sourceProcessor.onaudioprocess = onSourceOutput;

  // Keep audioprocess events going after source disconnect.

  sourceProcessor.connect(ctx.destination);

  var delayProcessor = ctx.createScriptProcessor(bufferSize, 1, 0);

  delayProcessor.onaudioprocess = onDelayOutput;

  var delayDuration = delayLength / ctx.sampleRate;

  for (var i = 0; i < sourceCount; ++i) {

    var delay = ctx.createDelay(delayDuration);

    delay.delayTime.value = delayDuration;

    delay.connect(delayProcessor);

    var source = ctx.createOscillator();

    source.frequency.value = 440 + 10 * i

    source.start(i * signalLength / ctx.sampleRate);

    source.stop((i + 1) * signalLength / ctx.sampleRate);

    source.connect(delay);

    source.connect(sourceProcessor);

    sources[i] = source;

  // Assuming the above Web Audio operations have already scheduled an event

  // to run in stable state and start the graph thread, schedule a subsequent

  // event to disconnect the sources, which will remove main thread connection

  // references before it knows the graph thread has started using the source

  // streams.

  SimpleTest.executeSoon(disconnectSources);

};

startTest();

</script>

</pre>

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