test_mp3_dataurl_duration.html

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<!DOCTYPE HTML>

<html>

<head>

<title>Bug 1975822 - mp3 duration via data: URL</title>

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

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

</head>

<body>

<audio id="a"></audio>

<script>

// CBR mp3 with no Xing/Info header, large enough that loading via

// FileReader.readAsDataURL exposes the timing path inside

// ChannelMediaResource where a non-HTTP channel was leaving the cache

// stream length unset and the demuxer reported Infinity duration.

// ffprobe reports 30.024 s.

const SRC = "cbr-no-xing.mp3";

const EXPECTED = 30.024;

add_task(async function test_mp3_dataurl_duration() {

  const blob = await fetch(SRC).then(r => r.blob());

  const dataUrl = await new Promise(resolve => {

    const fr = new FileReader();

    fr.onload = () => resolve(fr.result);

    fr.readAsDataURL(blob);

});

  const audio = document.getElementById("a");

  audio.src = dataUrl;

  // Wait for canplaythrough so any late metadata-vs-buffered race has

  // settled before we assert on the duration.

  await new Promise((resolve, reject) => {

    audio.addEventListener("canplaythrough", resolve, { once: true });

    audio.addEventListener("error", () => reject(audio.error), { once: true });

});

  ok(Number.isFinite(audio.duration),

     "data: URL mp3 duration should be finite, got " + audio.duration);

  ok(Math.abs(audio.duration - EXPECTED) < 0.1,

     "data: URL mp3 duration should be ~" + EXPECTED + "s, got " + audio.duration);

});

</script>

</body>

</html>