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+---
+title: AnalyserNode
+slug: Web/API/AnalyserNode
+tags:
+ - API
+ - AnalyserNode
+ - Interface
+ - NeedsTranslation
+ - Reference
+ - TopicStub
+ - Web Audio API
+translation_of: Web/API/AnalyserNode
+---
+<p>{{APIRef("Web Audio API")}}</p>
+
+<p>The <strong><code>AnalyserNode</code></strong><strong> </strong>interface represents a node able to provide real-time frequency and time-domain analysis information. It is an {{domxref("AudioNode")}} that passes the audio stream unchanged from the input to the output, but allows you to take the generated data, process it, and create audio visualizations.</p>
+
+<p>An <code>AnalyzerNode</code> has exactly one input and one output. The node works even if the output is not connected.</p>
+
+<p><img alt="Without modifying the audio stream, the node allows to get the frequency and time-domain data associated to it, using a FFT." src="https://mdn.mozillademos.org/files/9707/WebAudioFFT.png" style="height: 174px; width: 661px;"></p>
+
+<table class="properties">
+ <tbody>
+ <tr>
+ <th scope="row">Number of inputs</th>
+ <td><code>1</code></td>
+ </tr>
+ <tr>
+ <th scope="row">Number of outputs</th>
+ <td><code>1</code> (but may be left unconnected)</td>
+ </tr>
+ <tr>
+ <th scope="row">Channel count mode</th>
+ <td><code>"explicit"</code></td>
+ </tr>
+ <tr>
+ <th scope="row">Channel count</th>
+ <td><code>1</code></td>
+ </tr>
+ <tr>
+ <th scope="row">Channel interpretation</th>
+ <td><code>"speakers"</code></td>
+ </tr>
+ </tbody>
+</table>
+
+<h2 id="Inheritance">Inheritance</h2>
+
+<p>This interface inherits from the following parent interfaces:</p>
+
+<p>{{InheritanceDiagram}}</p>
+
+<h2 id="Properties">Properties</h2>
+
+<p><em>Inherits properties from its parent, </em><em>{{domxref("AudioNode")}}</em>.</p>
+
+<dl>
+ <dt>{{domxref("AnalyserNode.fftSize")}}</dt>
+ <dd>Is an unsigned long value representing the size of the FFT (<a href="http://en.wikipedia.org/wiki/Fast_Fourier_transform" title="/en-US/docs/">Fast Fourier Transform</a>) to be used to determine the frequency domain.</dd>
+ <dt>{{domxref("AnalyserNode.frequencyBinCount")}} {{readonlyInline}}</dt>
+ <dd>Is an unsigned long value half that of the FFT size. This generally equates to the number of data values you will have to play with for the visualization.</dd>
+ <dt>{{domxref("AnalyserNode.minDecibels")}}</dt>
+ <dd>Is a double value representing the minimum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte values — basically, this specifies the minimum value for the range of results when using <code>getByteFrequencyData()</code>.</dd>
+ <dt>{{domxref("AnalyserNode.maxDecibels")}}</dt>
+ <dd>Is a double value representing the maximum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte values — basically, this specifies the maximum value for the range of results when using <code>getByteFrequencyData()</code>.</dd>
+ <dt>{{domxref("AnalyserNode.smoothingTimeConstant")}}</dt>
+ <dd>Is a double value representing the averaging constant with the last analysis frame — basically, it makes the transition between values over time smoother.</dd>
+</dl>
+
+<h2 id="Methods">Methods</h2>
+
+<p><em>Inherits methods from its parent, </em><em>{{domxref("AudioNode")}}</em>.</p>
+
+<dl>
+ <dt>{{domxref("AnalyserNode.getFloatFrequencyData()")}}</dt>
+ <dd>Copies the current frequency data into a {{domxref("Float32Array")}} array passed into it.</dd>
+</dl>
+
+<dl>
+ <dt>{{domxref("AnalyserNode.getByteFrequencyData()")}}</dt>
+ <dd>Copies the current frequency data into a {{domxref("Uint8Array")}} (unsigned byte array) passed into it.</dd>
+</dl>
+
+<dl>
+ <dt>{{domxref("AnalyserNode.getFloatTimeDomainData()")}}</dt>
+ <dd>Copies the current waveform, or time-domain, data into a {{domxref("Float32Array")}} array passed into it.</dd>
+ <dt>{{domxref("AnalyserNode.getByteTimeDomainData()")}}</dt>
+ <dd>Copies the current waveform, or time-domain, data into a {{domxref("Uint8Array")}} (unsigned byte array) passed into it.</dd>
+</dl>
+
+<h2 id="Examples">Examples</h2>
+
+<div class="note">
+<p><strong>Note</strong>: See the guide <a href="/en-US/docs/Web/API/Web_Audio_API/Visualizations_with_Web_Audio_API">Visualizations with Web Audio API</a> for more information on creating audio visualizations.</p>
+</div>
+
+<h3 id="Basic_usage">Basic usage</h3>
+
+<p>The following example shows basic usage of an {{domxref("AudioContext")}} to create an <code>AnalyserNode</code>, then {{domxref("window.requestAnimationFrame()","requestAnimationFrame")}} and {{htmlelement("canvas")}} to collect time domain data repeatedly and draw an "oscilloscope style" output of the current audio input. For more complete applied examples/information, check out our <a href="http://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a> demo (see <a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js#L128-L205">app.js lines 128–205</a> for relevant code).</p>
+
+<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+var analyser = audioCtx.createAnalyser();
+
+ ...
+
+analyser.fftSize = 2048;
+var bufferLength = analyser.frequencyBinCount;
+var dataArray = new Uint8Array(bufferLength);
+analyser.getByteTimeDomainData(dataArray);
+
+// draw an oscilloscope of the current audio source
+
+function draw() {
+
+      drawVisual = requestAnimationFrame(draw);
+
+      analyser.getByteTimeDomainData(dataArray);
+
+      canvasCtx.fillStyle = 'rgb(200, 200, 200)';
+      canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
+
+      canvasCtx.lineWidth = 2;
+      canvasCtx.strokeStyle = 'rgb(0, 0, 0)';
+
+      canvasCtx.beginPath();
+
+      var sliceWidth = WIDTH * 1.0 / bufferLength;
+      var x = 0;
+
+      for(var i = 0; i &lt; bufferLength; i++) {
+
+        var v = dataArray[i] / 128.0;
+        var y = v * HEIGHT/2;
+
+        if(i === 0) {
+          canvasCtx.moveTo(x, y);
+        } else {
+          canvasCtx.lineTo(x, y);
+        }
+
+        x += sliceWidth;
+      }
+
+      canvasCtx.lineTo(canvas.width, canvas.height/2);
+      canvasCtx.stroke();
+    };
+
+    draw();</pre>
+
+<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', '#the-analysernode-interface', 'AnalyserNode')}}</td>
+ <td>{{Spec2('Web Audio API')}}</td>
+ <td> </td>
+ </tr>
+ </tbody>
+</table>
+
+<h2 id="Browser_compatibility">Browser compatibility</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</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="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>