---
title: AudioContext.createMediaElementSource()
slug: Web/API/AudioContext/createMediaElementSource
translation_of: Web/API/AudioContext/createMediaElementSource
---
<p>{{ APIRef("Web Audio API") }}</p>

<div>
<p>{{ domxref("AudioContext") }} 接口的 <code>createMediaElementSource() 方法用于创建一个新的 </code>{{ domxref("MediaElementAudioSourceNode") }} 对象,输入某个存在的 HTML {{htmlelement("audio")}} or {{htmlelement("video")}} 元素, 对应的音频即可被播放或者修改.</p>
</div>

<p>为寻求更多关于媒体元素音频源节点的具体信息,请查阅 {{ domxref("MediaElementAudioSourceNode") }} 参考页.</p>

<h2 id="语法">语法</h2>

<pre class="brush: js">var audioCtx = new AudioContext();
var source = audioCtx.createMediaElementSource(myMediaElement);</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>myMediaElement</code></dt>
 <dd>某个被期待被录入音频处理图修改的 {{domxref("HTMLMediaElement")}} 对象.</dd>
</dl>

<h3 id="返回值">返回值</h3>

<p>一个 {{domxref("MediaElementAudioSourceNode")}} 对象.</p>

<h2 id="示例">示例</h2>

<p>该示例由 {{htmlelement("audio") }} 元素,通过使用 <code>createMediaElementSource() 方法,</code>创建了一个音源,将其通过 {{ domxref("GainNode") }} 节点,输出到{{ domxref("AudioDestinationNode") }} 节点以播放.当鼠标指针移动时, <code>updatePage()</code> 函数被调用,该函数计算当前鼠标Y坐标与页面高度的比值, 改变 {{ domxref("GainNode") }} 节点的值以调整音量.您就可以通过鼠标上下移动而改变音乐的音量了.</p>

<div class="note">
<p><strong>Note</strong>: 您也可以 <a href="http://mdn.github.io/webaudio-examples/media-source-buffer/">浏览该示例的在线演示</a>, 或者 <a href="https://github.com/mdn/webaudio-examples/tree/master/media-source-buffer">浏览源代码</a>.</p>
</div>

<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var myAudio = document.querySelector('audio');
var pre = document.querySelector('pre');
var myScript = document.querySelector('script');

pre.innerHTML = myScript.innerHTML;

// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
var source = audioCtx.createMediaElementSource(myAudio);

// Create a gain node
var gainNode = audioCtx.createGain();

// Create variables to store mouse pointer Y coordinate
// and HEIGHT of screen
var CurY;
var HEIGHT = window.innerHeight;

// Get new mouse pointer coordinates when mouse is moved
// then set new gain value

document.onmousemove = updatePage;

function updatePage(e) {
    CurY = (window.Event) ? e.pageY : event.clientY + (document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop);

    gainNode.gain.value = CurY/HEIGHT;
}


// connect the AudioBufferSourceNode to the gainNode
// and the gainNode to the destination, so we can play the
// music and adjust the volume using the mouse cursor
source.connect(gainNode);
gainNode.connect(audioCtx.destination);</pre>

<div class="note">
<p><strong>Note</strong>: 作为调用<code> createMediaElementSource() </code>的结果,{{domxref("HTMLMediaElement")}} 的播放将会由AudioContext的音频处理图接管.所以对媒体进行播放/暂停等操作仍可通过media API与播放器面板来进行.</p>
</div>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Web Audio API', '#widl-AudioContext-createMediaElementSource-MediaElementAudioSourceNode-HTMLMediaElement-mediaElement', 'createMediaElementSource()')}}</td>
   <td>{{Spec2('Web Audio API')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

{{Compat("api.AudioContext.createMediaElementSource")}}

<h2 id="相关链接">相关链接</h2>

<ul>
 <li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>