IIRFilterNode.getFrequencyResponse()

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getFrequencyResponse() 方法在 IIRFilterNode interface takes the current filtering algorithm's settings and calculates the frequency response for frequencies specified in a specified array of frequencies.

The two output arrays, magResponseOutput and phaseResponseOutput , must be created before calling this method; they must be the same size as the array of input frequency values ( frequencyArray ).

句法

IIRFilterNode.getFrequencyResponse(frequencyArray, magResponseOutput, phaseResponseOutput);

参数

frequencyArray: Float32Array containing an array of frequencies, specified in Hertz, which you want to filter.
magResponseOutput: Float32Array to receive the computed magnitudes of the freqency response for each frequency value in the frequencyArray .
phaseResponseOutput: Float32Array to receive the computed phase response values in radians for each frequency value in the input frequencyArray .

返回值

undefined

异常

NotSupportedError

范例

In the following example we are using an IIR filter on a media stream (for a complete full demo, see our stream-source-buffer demo live, or read its source .) As part of this demo, we get the frequency responses for this IIR filter, for five sample frequencies. We first create the Float32Array objects we need, one containing the input frequencies, and two to receive the output magnitude and phase values:

var myFrequencyArray = new Float32Array(5);
myFrequencyArray[0] = 1000;
myFrequencyArray[1] = 2000;
myFrequencyArray[2] = 3000;
myFrequencyArray[3] = 4000;
myFrequencyArray[4] = 5000;
var magResponseOutput = new Float32Array(5);
var phaseResponseOutput = new Float32Array(5);

Next we create a <ul> element in our HTML to contain our results, and grab a reference to it in our JavaScript:

<p>IIR filter frequency response for: </p>
<ul class="freq-response-output">
</ul>

var freqResponseOutput = document.querySelector('.freq-response-output');

Finally, after creating our filter, we use getFrequencyResponse() to generate the response data and put it in our arrays, then loop through each data set and output them in a human-readable list at the bottom of the page:

var feedforwardCoefficients = [0.1, 0.2, 0.3, 0.4, 0.5];
var feedbackCoefficients = [0.5, 0.4, 0.3, 0.2, 0.1];
var iirFilter = audioCtx.createIIRFilter(feedforwardCoefficients, feedbackCoefficients);
  ...
function calcFrequencyResponse() {
  iirFilter.getFrequencyResponse(myFrequencyArray, magResponseOutput, phaseResponseOutput);
  for(i = 0; i <= myFrequencyArray.length-1;i++){
    var listItem = document.createElement('li');
    listItem.innerHTML = '<strong>' + myFrequencyArray[i] + 'Hz</strong>: Magnitude ' + magResponseOutput[i] + ', Phase ' + phaseResponseOutput[i] + ' radians.';
    freqResponseOutput.appendChild(listItem);
  }
}
calcFrequencyResponse();

规范

规范	状态	注释
Web 音频 API The definition of 'getFrequencyResponse()' in that specification.	工作草案

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`getFrequencyResponse`	Chrome 49	Edge 14	Firefox 50	IE 不支持 No	Opera 36	Safari ?	WebView Android 49	Chrome Android 49	Firefox Android 50	Opera Android 36	Safari iOS ?	Samsung Internet Android 5.0

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