Source code

Revision control

Copy as Markdown

Other Tools

<!DOCTYPE HTML>
<html>
<meta charset="utf-8">
<head>
<title>Test MediaStreamAudioSourceNode doesn't get data from cross-origin media resources</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
</head>
<body>
<pre id="test">
<script class="testbody" type="text/javascript">
SimpleTest.waitForExplicitFinish();
function binIndexForFrequency(frequency, analyser) {
return 1 + Math.round(frequency *
analyser.fftSize /
analyser.context.sampleRate);
}
function debugCanvas(analyser) {
var cvs = document.createElement("canvas");
document.body.appendChild(cvs);
// Easy: 1px per bin
cvs.width = analyser.frequencyBinCount;
cvs.height = 256;
cvs.style.border = "1px solid red";
var c = cvs.getContext('2d');
var buf = new Uint8Array(analyser.frequencyBinCount);
function render() {
c.clearRect(0, 0, cvs.width, cvs.height);
analyser.getByteFrequencyData(buf);
for (var i = 0; i < buf.length; i++) {
c.fillRect(i, (256 - (buf[i])), 1, 256);
}
requestAnimationFrame(render);
}
requestAnimationFrame(render);
}
function checkFrequency(an) {
an.getFloatFrequencyData(frequencyArray);
// We should have no energy when checking the data largely outside the index
// for 440Hz (the frequency of the sine wave), start checking an octave above,
// the Opus compression can add some harmonics to the pure since wave.
var maxNoiseIndex = binIndexForFrequency(880, an);
for (var i = maxNoiseIndex + 1; i < frequencyArray.length; i++) {
if (frequencyArray[i] > frequencyArray[maxNoiseIndex]) {
maxNoiseIndex = i;
}
}
// On the other hand, we should find a peak at 440Hz. Our sine wave is not
// attenuated, we're expecting the peak to reach 0dBFs.
var index = binIndexForFrequency(440, an);
info("energy at 440: " + frequencyArray[index] +
", threshold " + (an.maxDecibels - 10) +
"; max noise at index " + maxNoiseIndex +
": " + frequencyArray[maxNoiseIndex] );
if (frequencyArray[index] < (an.maxDecibels - 10)) {
return false;
}
// Let some slack, there might be some noise here because of int -> float
// conversion or the Opus encoding.
if (frequencyArray[maxNoiseIndex] > an.minDecibels + 40) {
return false;
}
return true;
}
var audioElement = new Audio();
audioElement.src = 'sine-440-10s.opus'
audioElement.loop = true;
var ac = new AudioContext();
var mediaElementSource = ac.createMediaElementSource(audioElement);
var an = ac.createAnalyser();
// Use no smoothing as this would just average with previous
// getFloatFrequencyData() calls. Non-seamless looping would introduce noise,
// and smoothing would spread this into calls after the loop point.
an.smoothingTimeConstant = 0;
frequencyArray = new Float32Array(an.frequencyBinCount);
// Uncomment this to check what the analyser is doing.
// debugCanvas(an);
mediaElementSource.connect(an)
audioElement.play();
// We want to check the we have the expected audio for at least two loop of
// the HTMLMediaElement, piped into an AudioContext. The file is ten seconds,
// and we use the default FFT size.
var lastCurrentTime = 0;
var loopCount = 0;
audioElement.onplaying = function() {
audioElement.ontimeupdate = function() {
// We don't run the analysis when close to loop point or at the
// beginning, since looping is not seamless, there could be an
// unpredictable amount of silence
var rv = checkFrequency(an);
info("currentTime: " + audioElement.currentTime);
if (audioElement.currentTime < 4 ||
audioElement.currentTime > 8){
return;
}
if (!rv) {
ok(false, "Found unexpected noise during analysis.");
audioElement.ontimeupdate = null;
audioElement.onplaying = null;
ac.close();
audioElement.src = '';
SimpleTest.finish()
return;
}
ok(true, "Found correct audio signal during analysis");
info(lastCurrentTime + " " + audioElement.currentTime);
if (lastCurrentTime > audioElement.currentTime) {
info("loopCount: " + loopCount);
if (loopCount > 1) {
audioElement.ontimeupdate = null;
audioElement.onplaying = null;
ac.close();
audioElement.src = '';
SimpleTest.finish();
}
lastCurrentTime = audioElement.currentTime;
loopCount++;
} else {
lastCurrentTime = audioElement.currentTime;
}
}
}
</script>