I'm looking for a C or C++ API that will give me real-time spectrum analysis of a waveform on Windows. I'm not entirely sure how large a sample window it should need to determine frequency content, but the smaller the better. For example, if it can work with a 0.5 second long sample and determine frequency content to the Hz, that would...
I'm wondering what's the easiest/best way to determine the magnitude of a given frequency in a sound. It's my understanding that a FFT function will return the magnitudes of all frequencies in a signal. I'm wondering if there is any shortcut I could use if I'm only concerned about a specific frequency. I'll be using the iPhone mic to r...
I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. Whenever I modify the amplitudes of the frequency bins before calling the iFFT the resulting signal contains some clicks and pops, especially when low frequencies are present in the signal (like drums or basses). However, this d...
Hello I want to use fft in MATLAB to analize some exprimental data saved as an excell file. my code: A=xlsread('Book.xls'); G=A'; x=G(2, : ); N=length(x); F=[-N/2:N/2-1]/N; X = abs(fft(x-mean(x),N)) X = fftshift(X); plot(F,X) But it plots a graph with a large 0Hz wrong component, my true frequency is about 395Hz and it is not shown i...
I'm looking at the aurioTouch sample application for the iPhone SDK. It has a basic spectrum analyzer implemented when you choose the "FFT" option. One of the things the app is lacking is X axis labels (i.e. the frequency labels). In the aurioTouchAppDelegate.mm file, in the function - (void)drawOscilloscope at line 652, it has the foll...
Hi, I want to implement Fast Fourier Transform algorithm with Hadoop. I know recursive-fft algorithm but I need your guideline in order to implement it Map/Reduce approach. Any suggestions? Thanks. ...
What I want to do is to have a subroutine that analyses every 200 milliseconds of a sound file which it is given and spits out the frequency intensity value (from 0 to 1 as a float) of a specific frequency range into an array which I later save. This value then goes on to be used as the opacity value for a graphic which is supposed to 's...
I'm trying to integrate the FFTW3 (a GNU FFT library written in C, http://www.fftw.org/) into an iPhone app. I downloaded the source code and I found there are hundreds of .h and .c files along with a lot of other files I can't recognize. I'm not a linux expert so I don't really understand how the .configure file and other similar files ...
Hi all, I want to make a program that would record audio data using PortAudio (I have this part done) and then display the frequency information of that recorded audio (for now, I'd like to display the average frequency of each of the group of samples as they come in). From some research I've done, I know that I need to do an FFT. So I...
Is there a nice (pure Java) open source libary to get the frequence spectrum of samples taken from a AudioInputStream? ...
Implementing a low pass FIR filter, when should one use FFT and IFFT instead of time-domain convolution? The goal is to achieve the lowest CPU time required for real-time calculations. As I know, FFT has about O(n log n) complexity, but convolution in the time domain is of O(n²) complexity. To implement a low pass filter in the frequen...
Does anyone have a favorite "go-to" paper, web site, etc., for explaining the basics behind Fourier theory / discrete Fourier transforms? I am not overly inclined mathematically, and while I know this particular domain requires some math skills I'm hoping for documentation that eases me into it so I have some understanding of intent by ...
I wish to apply a frequency-domain filter, such as a Low Pass or Band Pass, to each horizontal line of an image. Is this possible using opencv? ...
I recorded a radio signal into a .wav, I can open it in audacity and see that there is binary data encoded using a certain algorithm. Does anyone know of a way to process the signal that is contained within the .wav? so that i can extract the binary data from it? I know that I need to know the encoding algorithm for it to work properly,...
Hello, I've been reading a lot about Fast Fourier Transform and am trying to understand the low-level aspect of it. Unfortunately, Google and Wikipedia are not helping much at all.. and I have like 5 different algorithm books open that aren't helping much either. I'm trying to find the FFT of something simple like a vector [1,0,0,0]. ...
Hi, since I don't want to do it on my own, I am searching for a good FFT implementation for java. First I used this one here FFT Princeton but it uses objects and my profiler told me, that its not really fast due to this fact. So I googled again and found this one: FFT Columbia which is faster. Maybe one of you guys know another FFT imp...
Hi all, How should stereo (2 channel) audio data be represented for FFT? Do you A. Take the average of the two channels and assign it to the real component of a number and leave the imaginary component 0. B. Assign one channel to the real component and the other channel to the imag component. Is there a reason to do one or the other...
I'm implementing a face tracker on Android, and as a literature study, would like to identify the underlying technique of Android's FaceDetector. A brief Google search didn't yield anything informative, so I thought I'd take a look at the code. By looking at the Java source code, FaceDetector.java, there isn't much to be learned: FaceD...
I'm looking for an FFT library to translate into the D programming language for inclusion either in a library that I'm working on or (better yet) in the standard library. I need a fairly simple FFT with decent performance, not an uber-optimized one with blazing fast performance and zero simplicity/readability. However, it must meet the...
Does anybody know what the frequency range of auriotouch is in FFT mode? Also, where is it defined in the code if possible. I've been digging through it, but am not very familiar with FFT or frequency calculation so am not having much luck. I've also done some googling and searching on stackoverflow and have not found results there ei...