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---
title: AudioContext.createMediaStreamSource()
slug: Web/API/AudioContext/createMediaStreamSource
translation_of: Web/API/AudioContext/createMediaStreamSource
---
<p>{{ APIRef("Web Audio API") }}</p>
<div>
<p>{{ domxref("AudioContext") }}接口的<code>createMediaStreamSource()方法用于创建一个新的</code>{{ domxref("MediaStreamAudioSourceNode") }} 对象, 需要传入一个媒体流对象(MediaStream对象)(可以从 {{ domxref("navigator.getUserMedia") }} 获得MediaStream对象实例), 然后来自MediaStream的音频就可以被播放和操作。</p>
</div>
<p>更多关于媒体流音频源(media stream audio source nodes)的细节, 请参考{{ domxref("MediaStreamAudioSourceNode") }} 页面.</p>
<h2 id="语法">语法</h2>
<pre class="brush: js">var audioCtx = new AudioContext();
var source = audioCtx.createMediaStreamSource(stream);</pre>
<h3 id="参数">参数</h3>
<dl>
<dt>stream</dt>
<dd>一个{{domxref("MediaStream")}} 对象，把他传入一个音频处理器进行操作</dd>
</dl>
<h3 id="返回">返回</h3>
<p> {{domxref("MediaStreamAudioSourceNode")}}</p>
<h2 id="示例">示例</h2>
<p>本例中，我们从 {{ domxref("navigator.getUserMedia") }}获取媒体 (audio + video) 流,，把它传入 {{ htmlelement("video") }}中播放，并把视频调成静音，然后把获取到的audio传入 {{ domxref("MediaStreamAudioSourceNode") }}。接下来我们把获取到的audio传入{{ domxref("BiquadFilterNode") }} (可以把声音转化为低音)，输出到 {{domxref("AudioDestinationNode") }}.</p>
<p>{{ htmlelement("video") }} 元素下面滑动杆控制低音过滤器过滤的程度，滑动杆的值越大，低音更明显</p>
<div class="note">
<p><span style="font-size: 14px;"><strong>注意：你可以查看</strong></span> <a href="https://mdn.github.io/webaudio-examples/stream-source-buffer/">在线演示</a>，或者 <a href="https://github.com/mdn/webaudio-examples/tree/master/stream-source-buffer">查看源码</a>。</p>
</div>
<pre class="brush: js;highlight[23]">var pre = document.querySelector('pre');
var video = document.querySelector('video');
var myScript = document.querySelector('script');
var range = document.querySelector('input');
// getUserMedia获取流
// 把流放入MediaStreamAudioSourceNode
// 输出到video元素
if (navigator.mediaDevices) {
console.log('getUserMedia supported.');
navigator.mediaDevices.getUserMedia ({audio: true, video: true})
.then(function(stream) {
video.srcObject = stream;
video.onloadedmetadata = function(e) {
video.play();
video.muted = true;
};
// 创建MediaStreamAudioSourceNode
// Feed the HTMLMediaElement into it
var audioCtx = new AudioContext();
var source = audioCtx.createMediaStreamSource(stream);
// 创建二阶滤波器
var biquadFilter = audioCtx.createBiquadFilter();
biquadFilter.type = "lowshelf";
biquadFilter.frequency.value = 1000;
biquadFilter.gain.value = range.value;
// 把AudioBufferSourceNode连接到gainNode
// gainNode连接到目的地, 所以我们可以播放
// 音乐并用鼠标调节音量
source.connect(biquadFilter);
biquadFilter.connect(audioCtx.destination);
// Get new mouse pointer coordinates when mouse is moved
// then set new gain value
range.oninput = function() {
biquadFilter.gain.value = range.value;
}
})
.catch(function(err) {
console.log('The following gUM error occured: ' + err);
});
} else {
console.log('getUserMedia not supported on your browser!');
}
// dump script to pre element
pre.innerHTML = myScript.innerHTML;</pre>
<div class="note">
<p><span style="font-size: 14px;"><strong>注意</strong></span>: 调用<code>createMediaStreamSource()</code>, 来自于媒体流的音频回放将被重新传到AudioContext的处理器中。所以播放/暂停流仍然是可以通过media元素的API和自带的控制器控制。</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-createMediaStreamSource-MediaStreamAudioSourceNode-MediaStream-mediaStream', 'createMediaStreamSource()')}}</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.createMediaStreamSource")}}
<h2 id="查看更多">查看更多</h2>
<ul>
<li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>
|
