RTCRtpSender.getCapabilities() static function

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static function RTCRtpSender.getCapabilities() 返回 RTCRtpCapabilities object describing the codecs and capabilities supported by the RTCRtpSender .

You can, similarly, obtain the capabilities of RTCRtpReceiver s by calling the static function RTCRtpReceiver.getCapabilities() .

句法

let rtpCapabilities = RTCRtpSender.getCapabilities(kind);

参数

kind: DOMString indicating the type of media for which you wish to get the sender's capability to receive. All browsers support the primary media kinds: audio and 视频 .

返回值

RTCRtpCapabilities object stating what capabilities the browser has for sending the specified media kind over an RTCPeerConnection . If the browser doesn't have any support for the given media kind, the returned value is null .

描述

As a static function, this is always called using the form:

capabilities = RTCRtpSender.getCapabilities("audio");

The returned set of capabilities is the most optimistic possible list. It is entirely possible that certain combinations of options may fail to work when you actually try to use them.

调用 RTCRtpSender.getCapabilities() doesn't prime the browser in any way to handle media. Nothing is loaded, fetched, or otherwise prepared. It's simply a means of determining what might be usable before starting to try to access media.

Because the set of capabilities available tend to be stable for a length of time (people don't install and uninstall codecs and the like very often), the media capabilities can in whole or in part provide a cross-origin method for identifying a user. For that reason, in privacy-sensitive contexts, the browser may choose to obscure the capabilities; this might be done, for example, by leaving out rarely-used codec configurations.

范例

The function below returns a Boolean indicating whether or not the device supports sending H.264 video on an RTCRtpSender .

由于 RTCRtpSender.getCapabilities() actually only indicates probable support, H.264 support might still fail even after getting a positive response from this function.

function canSendH264() {
  let capabilities = RTCRtpSender.getCapabilities("video");
  capabilities.codecs.forEach((codec) => {
    if (codec.mimeType === "video/H264") {
      return true;
    }
  });
  return false;
}

规范

规范	状态	注释
WebRTC 1.0: Real-time Communication Between Browsers The definition of 'RTCRtpSender.getCapabilities()' in that specification.	候选推荐

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`getCapabilities()`	Chrome Yes	Edge 12	Firefox ?	IE 不支持 No	Opera Yes	Safari ?	WebView Android Yes	Chrome Android Yes	Firefox Android ?	Opera Android Yes	Safari iOS ?	Samsung Internet Android Yes

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元数据

最后修改： Aug 20, 2020

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