--- 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 < 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>