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---
title: HTMLCanvasElement.captureStream()
slug: Web/API/HTMLCanvasElement/捕获流
translation_of: Web/API/HTMLCanvasElement/captureStream
---
<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>
<p>{{CompatibilityTable}}</p>
<div id="compat-desktop">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Chrome</th>
<th>Firefox (Gecko)</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{CompatChrome(51.0)}}</td>
<td>{{CompatGeckoDesktop(43)}}<sup>[1]</sup></td>
<td>{{CompatNo}}</td>
<td>{{CompatOpera(36.0)}}</td>
<td>{{CompatUnknown}}</td>
</tr>
</tbody>
</table>
</div>
<div id="compat-mobile">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Android</th>
<th>Android Webview</th>
<th>Chrome for Android</th>
<th>Firefox Mobile (Gecko)</th>
<th>IE Mobile</th>
<th>Opera Mobile</th>
<th>Safari Mobile</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{CompatNo}}</td>
<td>{{CompatChrome(51.0)}}</td>
<td>{{CompatChrome(51.0)}}</td>
<td>{{CompatGeckoMobile(43)}}</td>
<td>{{CompatNo}}</td>
<td>{{CompatOpera(38)}}</td>
<td>{{CompatUnknown}}</td>
</tr>
</tbody>
</table>
</div>
<p>[1] <font>在Firefox 41和42中，此功能默认是禁用的; </font><font>将首选项</font> <code>canvas.capturestream.enabled</code> 设置 <code>true</code> 。</p>
<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>
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