2027433.html - mozsearch

Enable keyboard shortcuts

<!doctype html>

<html class="reftest-wait">

<head>

  <meta charset="utf-8">

  <title>Channel count change with playback rate</title>

</head>

<script>

  async function fetchMedia(url) {

    const request = new XMLHttpRequest();

    request.open("GET", url);

    request.responseType = "arraybuffer";

    request.send();

    await new Promise(r => request.onload = r);

    return new Uint8Array(request.response);

  async function run() {

    const audio = document.createElement('audio');

    const ms = new MediaSource();

    audio.src = URL.createObjectURL(ms);

    audio.playbackRate = 8.0;

    const metadataPromise = new Promise(r => audio.onloadedmetadata = r);

    await new Promise(r => ms.onsourceopen = r);

    const sb = ms.addSourceBuffer('audio/webm;codecs="opus"');

    const fourChannelUrl = "../opus-mapping2.webm";

    // HAVE_FUTURE_DATA (canplay) is not reached until the entire

    // second SimpleBlock is available.

    const fourChannelThirdBlockStart = 0x007B8;

    const fourChannelData = await fetchMedia(fourChannelUrl);

    sb.appendBuffer(fourChannelData.subarray(0, fourChannelThirdBlockStart));

    await new Promise(r => sb.onupdateend = r);

    const twoChannelUrl = "../detodos-short.webm";

    const twoChannelData = await fetchMedia(twoChannelUrl);

    sb.appendBuffer(twoChannelData);

    await new Promise(r => sb.onupdateend = r);

    // for tracks, as required by MediaStreamAudioSourceNode constructor

    await metadataPromise;

    const mediaStream = audio.captureStream();

    var ctx = new AudioContext();

    var srcNode = new MediaStreamAudioSourceNode(ctx, {mediaStream});

    var gain = new GainNode(ctx, {gain: 0.01}); // Low volume

    srcNode.connect(gain).connect(ctx.destination);

    ms.endOfStream();

    await audio.play();

    await new Promise(r => audio.onended = r);

    document.documentElement.removeAttribute("class");

  run();

</script>