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POhow to use FFT?
 

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  1. POhow to use FFT?
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    <p>I'm working on an android application which records sound and then gets the FFT of that recordning. I've been doing lots or research and found alot of things on stack overflow,, but im confused on what to use ,</p> <p>from this link: <a href="https://stackoverflow.com/questions/7604011/how-can-i-get-frequency-data-from-pcm-using-fft">How can I get frequency data from PCM using FFT</a></p> <p>i found this answer very useful:</p> <p>Assuming the audioData array contains the raw audio data, you need to create a Complex[] object from the audioData array as such:</p> <pre><code> Complex[] complexData = new Complex[audioData.length]; for (int i = 0; i &lt; complexData.length; i++) { complexData[i] = new Complex(audioData[i], 0); } </code></pre> <p>Now you can pass your complexData object as a parameter to your FFT function:</p> <pre><code> Complex[] fftResult = FFT.fft(complexData); </code></pre> <p>And i did that! but my issue is ,, is this all? do i need to do anything else? and what is FFT.fft(complexData) supposed to do?! </p> <p>Or do i have to use: fft.complexForward(a),or realForward(double[] a), or.... From this link: <a href="http://incanter.org/docs/parallelcolt/api/edu/emory/mathcs/jtransforms/fft/DoubleFFT_1D.html#complexForward%28double%5B%5D%29" rel="nofollow noreferrer">http://incanter.org/docs/parallelcolt/api/edu/emory/mathcs/jtransforms/fft/DoubleFFT_1D.html#complexForward%28double%5B%5D%29</a></p> <p>Note: i'm using this FFT class: <a href="http://www.cs.princeton.edu/introcs/97data/FFT.java" rel="nofollow noreferrer">http://www.cs.princeton.edu/introcs/97data/FFT.java</a> and this is the complex class to go with it: <a href="http://introcs.cs.princeton.edu/java/97data/Complex.java.html" rel="nofollow noreferrer">http://introcs.cs.princeton.edu/java/97data/Complex.java.html</a></p> <p>And i already imported the jtransform: import edu.emory.mathcs.jtransforms.fft.DoubleFFT_1D;</p>
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    1. CO@Paul R can you help me.
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    2. COWhat are you concerned about? Is there specifically something you're thinking must also be done? Using the complex form is more general, but for your purposes you're input values are all real numbers. Using either method should yield the same results. Forward is the form you want, btw.
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    3. COno, im just lost because from this link: http://stackoverflow.com/questions/7674877/how-to-get-frequency-from-fft-result if you can see in the 1st answer there are losts of steps to be done like windowing, and stuff.... so i don't know! so are you telling me my code is good? no need to add or edit anything? @Brad
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