files/ja/web/api/baseaudiocontext/creategain/index.html


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

<div>
<p>インターフェースの<code>createGain()</code>メソッドは、音声の全体的なボリュームを操作する{{ domxref("GainNode") }}を生成します。</p>
</div>

<h2 id="構文">構文</h2>

<pre class="brush: js">var audioCtx = new AudioContext();
var gainNode = audioCtx.createGain();</pre>

<h3 id="Description" name="Description">戻り値</h3>

<p>{{domxref("GainNode")}}</p>

<h2 id="Example" name="Example">例</h2>

<p>次の例では{{domxref("AudioContext")}}、<code>GainNode</code>を生成する基本的な使い方を示しています。生成した<code>GainNode</code>は、Muteボタンを押したときに<code>gain</code>プロパティの値を設定することで、無音・無音解除するために使っています。完全な例と情報は、<a href="http://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a>デモ(<a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js">ソースの閲覧</a>)をクリックしてください。</p>

<pre class="brush: html">&lt;div&gt;
  &lt;a class="mute"&gt;Mute button&lt;/a&gt;
&lt;/div&gt;</pre>

<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var gainNode = audioCtx.createGain();
var mute = document.querySelector('.mute');

source.connect(gainNode);
gainNode.connect(audioCtx.destination);

  ...

mute.onclick = voiceMute;

function voiceMute() {
  if(mute.id == "") {
    gainNode.gain.value = 0;
    mute.id = "activated";
    mute.innerHTML = "Unmute";
  } else {
    gainNode.gain.value = 1;
    mute.id = "";
    mute.innerHTML = "Mute";
  }
}</pre>

<h2 id="仕様">仕様</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-createGain-GainNode', 'createGain()')}}</td>
   <td>{{Spec2('Web Audio API')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="ブラウザ互換性">ブラウザ互換性</h2>

<div>{{CompatibilityTable}}</div>

<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 (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome(10.0)}}{{property_prefix("webkit")}}</td>
   <td>{{CompatGeckoDesktop(25.0)}} </td>
   <td>{{CompatNo}}</td>
   <td>15.0{{property_prefix("webkit")}}<br>
    22 (unprefixed)</td>
   <td>6.0{{property_prefix("webkit")}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
   <th>Chrome for Android</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatUnknown}}</td>
   <td>26.0</td>
   <td>1.2</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>33.0</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="参考">参考</h2>

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