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---
title: AudioContext.createMediaStreamDestination()
slug: Web/API/AudioContext/createMediaStreamDestination
translation_of: Web/API/AudioContext/createMediaStreamDestination
---
<p>{{ APIRef("Web Audio API") }}</p>
<div>
<p>{{ domxref("AudioContext") }}接口的<code>createMediaStreamDestination()方法用于创建一个新的对象，该对象关联着表示音频流的一个</code> <a href="/en-US/docs/WebRTC">WebRTC</a> {{domxref("MediaStream")}} ,音频流可以存储在本地文件或者被发送到另外一台计算机.</p>
</div>
<p>The {{domxref("MediaStream")}} is created when the node is created and is accessible via the {{domxref("MediaStreamAudioDestinationNode")}}'s <code>strea<dfn>m</dfn></code> attribute. This stream can be used in a similar way as a <code>MediaStream</code> obtained via {{domxref("navigator.getUserMedia") }} — it can, for example, be sent to a remote peer using the <code>RTCPeerConnection</code> <code>addStream()</code> method.</p>
<p>For more details about media stream destination nodes, check out the {{domxref("MediaStreamAudioDestinationNode")}} reference page.</p>
<h2 id="语法">语法</h2>
<pre class="brush: js">var audioCtx = new AudioContext();
var destination = audioCtx.createMediaStreamDestination();</pre>
<h3 id="返回值">返回值</h3>
<p>A {{domxref("MediaStreamAudioDestinationNode")}}.</p>
<h2 id="Example">Example</h2>
<p>In the following simple example, we create a {{domxref("MediaStreamAudioDestinationNode")}}, an {{ domxref("OscillatorNode") }} and a {{ domxref("MediaRecorder") }} (the example will therefore only work in Firefox at this time.) The <code>MediaRecorder</code> is set up to record information from the <code>MediaStreamDestinationNode</code>.</p>
<p>When the button is clicked, the oscillator starts, and the <code>MediaRecorder</code> is started. When the button is stopped, the oscillator and<code> MediaRecorder</code> both stop. Stopping the <code>MediaRecorder</code> causes the <code>dataavailable</code> event to fire, and the event data is pushed into the <code>chunks</code> array. After that, the <code>stop</code> event fires, a new <code>blob</code> is made of type opus — which contains the data in the <code>chunks</code> array, and a new window (tab) is then opened that points to a URL created from the blob.</p>
<p>From here, you can play and save the opus file.</p>
<pre class="brush: html;highlight[17]"><!DOCTYPE html>
<html>
<head>
<title>createMediaStreamDestination() demo</title>
</head>
<body>
<h1>createMediaStreamDestination() demo</h1>
<p>Encoding a pure sine wave to an Opus file </p>
<button>Make sine wave</button>
<audio controls></audio>
<script>
var b = document.querySelector("button");
var clicked = false;
var chunks = [];
var ac = new AudioContext();
var osc = ac.createOscillator();
var dest = ac.createMediaStreamDestination();
var mediaRecorder = new MediaRecorder(dest.stream);
osc.connect(dest);
b.addEventListener("click", function(e) {
if (!clicked) {
mediaRecorder.start();
osc.start(0);
e.target.innerHTML = "Stop recording";
clicked = true;
} else {
mediaRecorder.stop();
osc.stop(0);
e.target.disabled = true;
}
});
mediaRecorder.ondataavailable = function(evt) {
// push each chunk (blobs) in an array
chunks.push(evt.data);
};
mediaRecorder.onstop = function(evt) {
// Make blob out of our blobs, and open it.
var blob = new Blob(chunks, { 'type' : 'audio/ogg; codecs=opus' });
document.querySelector("audio").src = URL.createObjectURL(blob);
};
</script>
</body>
</html></pre>
<div class="note">
<p><strong>Note</strong>: You can <a href="https://mdn.github.io/webaudio-examples/create-media-stream-destination/index.html">view this example live</a>, or <a href="https://github.com/mdn/webaudio-examples/blob/master/create-media-stream-destination/index.html">study the source code</a>, on Github.</p>
</div>
<h2 id="Specifications">Specifications</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-createMediaStreamDestination-MediaStreamAudioDestinationNode', 'createMediaStreamDestination()')}}</td>
<td>{{Spec2('Web Audio API')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
{{Compat("api.AudioContext.createMediaStreamDestination")}}
<h2 id="See_also">See also</h2>
<ul>
<li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>
|
