test_delayNodeTailWithReconnect.html

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<head>

  <title>Test tail time lifetime of DelayNode after input finishes and new input added</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" />

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<body>

<pre id="test">

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

SimpleTest.waitForExplicitFinish();

// The buffer source will start on a block boundary, so keeping the signal

// within one block ensures that it will not cross AudioProcessingEvent buffer

// boundaries.

const signalLength = 128;

const bufferSize = 1024;

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

var delayBufferCount = 50;

var delayBufferOffset;

const delayLength = delayBufferCount * bufferSize;

var phase = "initial";

var sourceCount = 0;

var delayCount = 0;

var oscillator;

var delay;

var source;

function applySignal(buffer, offset) {

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

    buffer.getChannelData(0)[offset + i] = Math.cos(Math.PI * i / signalLength);

function bufferIsSilent(buffer, out) {

  for (var i = 0; i < buffer.length; ++i) {

    if (buffer.getChannelData(0)[i] != 0) {

      if (out) {

        out.soundOffset = i;

      return false;

  return true;

function onDelayOutput(e) {

  switch(phase) {

  case "initial":

    // Wait for oscillator sound to exit delay

    if (bufferIsSilent(e.inputBuffer))

      break;

    phase = "played oscillator";

    break;

  case "played oscillator":

    // First tail time has expired.  Start second source and remove references

    // to the delay and connected second source.

    oscillator.disconnect();

    source.connect(delay);

    source.start();

    source = null;

    delay = null;

    phase = "started second source";

    break;

  case "second tail time":

    if (delayCount == delayBufferCount) {

      var ctx = e.target.context;

      var expected = ctx.createBuffer(1, bufferSize, ctx.sampleRate);

      applySignal(expected, delayBufferOffset);

      compareBuffers(e.inputBuffer, expected);

      e.target.onaudioprocess = null;

      SimpleTest.finish();

  delayCount++;

function onSourceOutput(e) {

  switch(phase) {

  case "started second source":

    var out = {};

    if (!bufferIsSilent(e.inputBuffer, out)) {

      delayBufferCount += sourceCount;

      delayBufferOffset = out.soundOffset;

      phase = "played second source";

    break;

  case "played second source":

    SpecialPowers.forceGC();

    SpecialPowers.forceCC();

    phase = "second tail time";

    e.target.onaudioprocess = null;

  sourceCount++;

function startTest() {

  var ctx = new AudioContext();

  var delayDuration = delayLength / ctx.sampleRate;

  delay = ctx.createDelay(delayDuration);

  delay.delayTime.value = delayDuration;

  var processor1 = ctx.createScriptProcessor(bufferSize, 1, 0);

  delay.connect(processor1);

  processor1.onaudioprocess = onDelayOutput;

  // Signal to trigger initial tail time reference

  oscillator = ctx.createOscillator();

  oscillator.start(0);

  oscillator.stop(100/ctx.sampleRate);

  oscillator.connect(delay);

  // Short signal, not started yet, with a ScriptProcessor to detect when it

  // starts.  It should finish before garbage collection.

  var buffer = ctx.createBuffer(1, signalLength, ctx.sampleRate);

  applySignal(buffer, 0);

  source = ctx.createBufferSource();

  source.buffer = buffer;

  var processor2 = ctx.createScriptProcessor(bufferSize, 1, 0);

  source.connect(processor2);

  processor2.onaudioprocess = onSourceOutput;

};

startTest();

</script>

</pre>

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