MediaSource.addSourceBuffer()

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这是一个实验中的功能
此功能某些浏览器尚在开发中,请参考浏览器兼容性表格以得到在不同浏览器中适合使用的前缀。由于该功能对应的标准文档可能被重新修订,所以在未来版本的浏览器中该功能的语法和行为可能随之改变。

MediaSource 的 addSourceBuffer() 方法会根据给定的 MIME 类型创建一个新的 SourceBuffer 对象,然后会将它追加到 MediaSource 的 SourceBuffers 列表中。

语法

var sourceBuffer = mediaSource.addSourceBuffer(mimeType);

参数

mimeType
你想创建的 source buffer 的 MIME 类型。

返回

一个 SourceBuffer 对象。

错误( Errors )

下面的错误可能会在调用该方法时被抛出。

Error Explanation
InvalidAccessError 提交的 mimeType 是一个空字符串。
InvalidStateError MediaSource.readyState 的值不等于 open.
NotSupportedError 当前浏览器不支持你提交的 mimeType , 或者 it is not compatible with the mimeTypes specified for the SourceBuffer objects that already exist in MediaSource.sourceBuffers.
QuotaExceededError The user agent can't handle any more SourceBuffer objects, or creating a SourceBuffer based on this mimeType would result in an unsupported SourceBuffer configuration.

Example

The following snippet is from a simple example written by Nick Desaulniers (view the full demo live, or download the source for further investigation.)

var assetURL = 'frag_bunny.mp4';
// Need to be specific for Blink regarding codecs
// ./mp4info frag_bunny.mp4 | grep Codec
var mimeCodec = 'video/mp4; codecs="avc1.42E01E, mp4a.40.2"';

if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) {
  var mediaSource = new MediaSource;
  //console.log(mediaSource.readyState); // closed
  video.src = URL.createObjectURL(mediaSource);
  mediaSource.addEventListener('sourceopen', sourceOpen);
} else {
  console.error('Unsupported MIME type or codec: ', mimeCodec);
}

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();
      video.play();
      //console.log(mediaSource.readyState); // ended
    });
    sourceBuffer.appendBuffer(buf);
  });
};

Specifications

Specification Status Comment
Media Source Extensions
addSourceBuffer()
Recommendation Initial definition.

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23 (Yes) 25.0 (25.0)[1]
42.0 (42.0)
11[2] 15 8
Feature Android Edge Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 4.4.4 (Yes)

未实现

未实现 11 30 未实现

[1] Available after switching the about:config preference media.mediasource.enabled to true. In addition, support was limited to a whitelist of sites, for example YouTube, Netflix, and other popular streaming sites. The whitelist was removed and Media Source Extensions was enabled by default in 42+ for all sites.

[2] Only works on Windows 8+.

See also

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