MediaSource.activeSourceBuffers

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

實驗性質: 這是一個實驗中的功能
此功能在某些瀏覽器尚在開發中，請參考兼容表格以得到不同瀏覽器用的前輟。

activeSourceBuffers 是 MediaSource 介面的唯讀屬性，回傳一個 SourceBufferList 物件，含有在 SourceBuffers 之中的 SourceBuffer 物件子集合—物件的串列提供被選擇的影片軌 (video track), 啟用的音軌 (audio tracks), 以及顯示或隱藏的字軌。

語法

var myActiveSourceBuffers = mediaSource.activeSourceBuffers;

回傳值

一個 SourceBufferList 。

範例

以下的片段基於 Nick Desaulniers 所編纂的簡單範例（觀看實際演示，或者下載原始碼以利更進一步研究。）

function sourceOpen (_) {
  //console.log(this.readyState); // open
  var mediaSource = this;
  var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  fetchAB(assetURL, function (buf) {
    sourceBuffer.addEventListener('updateend', function (_) {
      mediaSource.endOfStream();
      console.log(mediaSource.activeSourceBuffers);
      // will contain the source buffer that was added above,
      // as it is selected for playing in the video player
      video.play();
      //console.log(mediaSource.readyState); // ended
    });
    sourceBuffer.appendBuffer(buf);
  });
};

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