Has anybody used the apple FFT for an iPhone app yet or know where I might find a sample application as to how to use it? I know that apple has some sample code posted, but I'm not really sure how to implement it into an actual project. ...
I don't know if this is even possible to do, but thought I would ask, I suspect that if it is possible, it would be changed in the - (void) renderFFTToTex routine. Does anybody have any ideas about doing this or other suggestions that they could recommend? Thank you. ...
Hi folks, I am looking for a library that can accept a chunk of audio data and return the average amplitude over time within a given frequency band. I've already asked this question over at comp.dsp, but it's clear to me that acquiring the know-how to build this on my own using a basic FFT library is going to require more time and energ...
I want to write a program in Java that uses fast Fourier transformation. The program reads data every 5 milliseconds seconds from sensors and is supposed to do something with the data every 200 milliseconds based on the data from the last five seconds. Is there a good library in Java that provides a way to do Fourier transformation with...
I take blocks of incoming data and pass them through fftw to get some spectral information. Everything seems to be working, however I think I'm getting some aliasing issues. I've been trying to work out how to implement a hann window on my blocks of data. Google has failed me for examples. Any ideas or links I should be looking at? dou...
Hi, im trying to implement a gaussian blur with the use of FFT and could find here the following recipe. This means that you can take the Fourier transform of the image and the filter, multiply the (complex) results, and then take the inverse Fourier transform. I've got a kernel K, a 7x7 Matrix and a Image I, a 512x512 Matr...
I've tried looking up how I might go about this for a while now, and maybe I am using the wrong terminology in my searches or it's way too advanced for me. I basically want to be able to analyze audio files in real-time. I know hardly anything about audio processing so I should probably start small and work my way up. Eventually I'd like...
Hi, Im trying to do a screen-flashing application, that flashes the screen according to the music(which will be frequencies, such as healing frequencies, etc...). I already made the player and know how will I make the screen flash, but I need to make the screen flash super fast according to the music, for example if the music speeds up, ...
hi i used fft function in numpy which resulted in a complex array.how to get the exact frequency values? ...
for a school project I am trying to make an android application that, once started, will perform a spectrum analysis of live audio received from the microphone or a bluetooth headset. I know I should be using FFT, and have been looking at moonblink's open source audio analyzer ( http://code.google.com/p/moonblink/wiki/Audalyzer ) but am ...
I have a real vector time series x of length T and a filter h of length t << T. h is a filter in fourier space, real and symmetric. It is approximately 1/f. I would like to filter x with h to get y. Suppose t == T and FFT's of length T could fit into memory (neither of which are true). To get my filtered x in python, I would do: impor...
Hi, I've got a FFT magnitude spectrum and I want to create a filter from it that selectively passes periodic noise sources (e.g. sinewave spurs) and zero's out the frequency bins associated with the random background noise. I understand sharp transitions in the freq domain will create ringing artifacts once this filter is IFFT back to t...
Hello, I'm not a DSP expert, but I understand that there are two ways that I can apply a discrete time-domain filter to a discrete time-domain waveform. The first is to convolve them in the time domain, and the second is to take the FFT of both, multiply both complex spectrums, and take IFFT of the result. One key difference in these met...
Possible Duplicate: Fast fourier transform in c# I am looking for an example of performing a real time FFT (Fast Fourier Transform) of line in or mic audio data in C#. My goal is to determine in real time if a particular note is present in the audio data. Any examples appreciated. ...
Hi, I've read some explanations of how autocorrelation can be more efficiently calculated using the fft of a signal, multiplying the real part by the complex conjugate (fourier domain), then using the inverse fft, but I'm having trouble realizing this in matlab because at a detailed level, I don't really know what I'm doing. :o) Any k...
I'm currently implementing a two dimensional FFT for real input data using opencl (more specifically a fast 2D convolution using FFTs, so I only need something which behaves similary enough to apply the convolution to). The 2D FFT is implemented using an 1D FFT on the rows and afterwards an 1D FFT on the cols. To make this more efficien...
I want to implement some image-processing algorithms which are intended to run on a beagleboard. These algorithms use convolutions extensively. I'm trying to find a good C implementation for 2D convolution (probably using the Fast Fourier Transform). I also want the algorithm to be able to run on the beagleboard's DSP, because I've heard...
I have to perform a FFT for a .wav file in an iPhone application. I have seen FFT algorithms out there, but how would I go about parsing a WAV file and using in such an algorithm? Should I convert the WAV file to NSData or something else? Has anyone successfully performed a FFT of a WAV file in the iPhone before? I tried to use iPhon...
Here is the scenario: using a spectrum analyzer i have the input values and the output values. the number of samples is 32000 and the sampling rate is 2000 samples/sec, and the input is a sine wave of 50 hz, the input is current and the output is pressure in psi. How do i calculate the frequency response from this data using MATLAB, usi...
Sorry this is the first time for me to ask question here, I've given a FFT function void fft_1d(int n, float xr[256], float xi[256], int ntype) { /* compute the FFT of a complex signal xr and xi are the real and imaginary parts respectively xr and xi contain the signal as input and the FT as output n is the number of po...