---
title: HTMLCanvasElement.captureStream()
slug: Web/API/HTMLCanvasElement/captureStream
translation_of: Web/API/HTMLCanvasElement/captureStream
original_slug: Web/API/HTMLCanvasElement/捕获流
---
<div>{{APIRef("Media Capture and Streams")}}{{SeeCompatTable}}</div>

<p>该 <code><strong>HTMLCanvasElement</strong></code><strong><code>.captureStream()</code></strong> 方法返回的 {{domxref("CanvasCaptureMediaStream")}} 是一个实时视频捕获的画布。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox"><var>MediaStream</var> = <var>canvas</var>.captureStream(<var>frameRate</var>);
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>frameRate</code> 可选</dt>
 <dd><font><font>设置双精准度浮点值为每个帧的捕获速率。</font><font>如果未设置，则每次画布更改时都会捕获一个新帧。</font><font>如果设置为</font></font><code>0</code><font><font>，则会捕获单个帧。</font></font></dd>
</dl>

<h3 id="返回值">返回值</h3>

<p>对一个 {{domxref("MediaStream")}} <font>对象</font><font>的引用</font>.</p>

<h2 id="例子">例子</h2>

<pre class="brush: js"><code>//</code>获取所需要截取媒体流的canvas element
var canvasElt = document.querySelector('canvas');

//<code>截取到媒体流</code>
var stream = canvasElt.captureStream(25); // 25 FPS

//使用媒体流
// E.g.使用RTCPeerConnection来传输给其它的电脑
// 下面的pc是其他地方创建的一个RTCPeerConnection
pc.addStream(stream);
</pre>

<h2 id="产品规格">产品规格</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('Media Capture DOM Elements', '#widl-HTMLCanvasElement-captureStream-CanvasCaptureMediaStream-double-frameRate', 'HTMLCanvasElement.captureStream()')}}</td>
   <td>{{Spec2('Media Capture DOM Elements')}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性"><font><font>浏览器兼容性</font></font></h2>

{{Compat("api.HTMLCanvasElement.captureStream")}}

<h2 id="看看其他">看看其他</h2>

<ul>
 <li>{{domxref("CanvasCaptureMediaStream")}},所属接口.</li>
 <li>{{domxref("HTMLMediaElement.captureStream()")}}, 允许从一个媒体中获取流</li>
 <li>{{domxref("MediaStream")}}</li>
 <li>{{domxref("Media Capture and Streams API")}}</li>
</ul>