89 lines
3 KiB
HTML
89 lines
3 KiB
HTML
<!DOCTYPE HTML>
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<html>
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<head>
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<title>HE-AAC decoding test</title>
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<script src="/tests/SimpleTest/SimpleTest.js"></script>
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<script type="text/javascript" src="mediasource.js"></script>
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<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
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</head>
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<body>
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<pre id="test">
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<script class="testbody" type="text/javascript">
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SimpleTest.waitForExplicitFinish();
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const SOURCE_FILE = "whitenoise-he-aac-5s.mp4";
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// This test checks when decoding HE-AAC using MediaSource or HTTP playback, the
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// audio is decoded correctly (in particular with the SBR part). This means
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// that the extradata describing the encoded AAC stream have been communicated
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// correctly to the audio decoder. For this, we check that there is energy
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// above 10kHz using the Web Audio API when playing white noise, which has
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// maximum energy accross the audible spectrum.
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// Return the index corresponding for a particular frequency in an array
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// containing frequency data from a FFT.
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function binIndexForFrequency(frequency, fftSize, sampleRate) {
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return (1 + Math.round((frequency * fftSize) / sampleRate));
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}
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async function checkHighFrequencyContent(element) {
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const ac = new AudioContext();
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await ac.resume();
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const mediaElementSource = ac.createMediaElementSource(element);
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const analyser = new AnalyserNode(ac);
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// Undo the volume scaling applied globally during test. This is fine because
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// the audio isn't routed to an actual audio output device in this test, it's
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// just analyzed with the Web Audio API.
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const gain = new GainNode(ac);
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const testVolumeScaling =
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parseFloat(SpecialPowers.getCharPref("media.volume_scale"));
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gain.gain.value = 1 / parseFloat(testVolumeScaling);
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mediaElementSource.connect(gain).connect(analyser)
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const spectrum = new Float32Array(analyser.frequencyBinCount);
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const indexFor15kHz =
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binIndexForFrequency(15000, analyser.fftSize, ac.sampleRate);
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// Wait a few hundreds of milliseconds
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while (!element.ended) {
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await once(element, "timeupdate");
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analyser.getFloatFrequencyData(spectrum);
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if (spectrum[indexFor15kHz] > -50) {
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ok(spectrum[indexFor15kHz] > -50,
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`Energy present at 15kHz (bin index: ${indexFor15kHz}) when playing white noise encoded in HE-AAC ${spectrum[indexFor15kHz]}`);
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return;
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}
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}
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ok(false,
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`No energy present at 15kHz (bin index: ${indexFor15kHz}) when playing white noise encoded in HE-AAC (last value ${spectrum[indexFor15kHz]})`);
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}
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runWithMSE(async (ms, el) => {
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// First check with MSE playback
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el.controls = true;
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await once(ms, "sourceopen");
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const audiosb = ms.addSourceBuffer('audio/mp4; codecs="mp4a.40.5"');
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await fetchAndLoad(audiosb, SOURCE_FILE, [""], "");
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ms.endOfStream();
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el.play();
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once(el, "playing");
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await checkHighFrequencyContent(el);
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// Redo the same test, with HTTP playback
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el.src = SOURCE_FILE;
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el.play();
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once(el, "playing");
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await checkHighFrequencyContent(el);
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SimpleTest.finish();
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});
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</script>
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</pre>
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</body>
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</html>
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