### Real time pitch detection

I'm trying to do real time pitch detection of a users singing, but I'm running into alot of problems. I've tried lots of methods, including FFT (FFT Problem (Returns random results)) and...

### How to compute ifft from fft?

I've done a fft to get fundamental frequency in real time and to implement high and low pass filters. Now I want to be able to record to a .wav file after I apply a filter. First I'll have to...

### Why does negative number show up when I do FFT on a Gaussian?

I'm using this fftw library. Currently I'm trying to plot a 2D Gaussian in the form e^(-(x^2+y^2)/a^2). Here is the code: using namespace std; int main(int argc, char** argv ){ fftw_complex *in,...

### 1d linear convolution in ANSI C code?

Rather than reinvent the wheel, I wonder if anyone could refer me to a 1D linear convolution code snippet in ANSI C? I did a search on google and in stack overflow, but couldn't find anything in C...

### Signal analysis: amplitude estimation in MATLAB

I am trying to estimate the amplitude of a signal in MATLAB: As can be seen, I can't simply take the max() and min() to get the amplitude. The signal continually wanders, and in any case isn't...

### Shorten the size of time domain data

I have an impulse response of 150ms in length. But most of the signal after 30ms is close to zero. So I am assuming that their effect on the spectrum after FFT is very small. I want to shorten the...

### FFTW and OpenCV's C++ interface, real and imaginary part in Mat output

I'm trying to code a FFT/IFFT function with FFTW 3.3 and OpenCV 2.1 using the C++ interface. I've seen a lot of examples using the old OpenCV formats and I did a direct conversion, but something...

### what is the PSD unit by using FFT method

I'm just doing a power spectral density analysis of a signal in time domain. I'm following the fft method described in : http://www.mathworks.com/support/tech-notes/1700/1702.html It gives the...

### Build VLC for iOS, get the "FFTW3 lib not found. Set FFTW3_DIR to find it." error

I want to build vlc for iOS. My environment is MacOS 10.8.3, Xcode4.6.2 with iOS6.1 SDK. I cloned the vlc lib form https://github.com/videolan/vlc.git, cd into the /extras/package/ios, and run the...

### OpenCV VideoWriter using ffmpeg with "Could not open codec 'libx264'" Error

I am new to OpenCV, and I want write Mat images into video using VideoWriter on Ubuntu 12.04. But when constructing VideoWriter, errors came out. It seems that OpenCV invoke ffmpeg API using...

### find RMS value in frequency domain

i would like to find RMS value in frequency domain,i used this site for help http://www.dsprelated.com/showmessage/123177/1.php but there it is calculated using FFT,but what if i am using...

### Optimal value of sampling frequency for guitar notes detection

I am running FFT algorithm to detect the music note played on a guitar. The frequencies that I am interested are in the range 65.41Hz (C2) to 1864.7Hz (A#6). If I set the sampling frequency of...

### how to get phase fft of a signal &-- can i get phase in time domain?

i can get magnitude of signal coming from .wav file , but how to get the phase of that signal too ,,, Here is the where i browse for .wav file and extract the signal def browse_wav(self): ...

### Python numpy equivalent of bandpower() from MATLAB

I am using Python numpy's ftt.ftt() method to generate the fourier transform of a signal. However I want to calculate the bandpower over a range of frequencies. MATLAB has the method...

### analyzing FFT data for mean frequency?

I used numpy fft.fft to analyze some time series data (black) and generate a plot like the following: From the FFT data (in red) i calculated mean frequency by multiplying x*y for each data point...

### Generating K-space from magnitude and phase

My question might be simple but I really need to make sure that the process I am doing is valid. The MRI scanner acquires k-space data, S, and then takes 3D inverse Fourier Transform to...

While compiling, I get the following error: undefined reference to `gr::fft::window::blackman_harris(int, int) I know that this linker error is due to not having the gnuradio linker flag in my...

### C# Identify blur image with FFT

I'm looking for a way to identify if an image is blur in C#. I saw this post but I did not see the way to apply to my case. I found the AForge.dll to apply the FFT to my Image. I'm looking for a...

### Importing/Using p5.Sound into React

I'm trying to get p5.sound into my React app, after having successfully gotten p5.js canvas functionality working. I have a p5Wrapper for my p5 sketch. And as I said the canvas functionality...

### Audio Frequencies in Python

I'm writing a code to analyse a single audio frequency sung by a voice. I need a way to analyse the frequency of the note. Currently I am using PyAudio to record the audio file, which is stored as...

### How to properly scale frequency axis in Fast Fourier Transform?

I am trying some sample code taking the FFT of a simple sinusoidal function. Below is the code import numpy as np from matplotlib import pyplot as plt N = 1024 limit = 10 x = np.linspace(-limit,...

### Angular spectrum method using python

I am trying to numerically propagate a given (electric) field using the angular spectrum method. For this I am following "Principles and Applications of Fourier Optics" (Robert K. Tyson) Chapter...

### How to import and utilize P5.Sound in Vue?

I have been trying to make a music visualizer app using Vue and P5, and after tinkering with P5 using this article as my guide...

### How do I import sklearn on python 3.5.0 without a Type error?

I installed the prerequisites to install sklearn via this page: https://scikit-learn.org/stable/install.html and everything installed fine. However, when I attempt to import sklearn I receive the...

### plot numpy fft in python returns wrong plot

I am trying to use numpy fft to plot some data from a dataframe : plt.plot(np.fft.fft(df_valid_daily_activity.stepsDaily)) I get this : I don't understand why the plot is so steep in the...

### Spectrogram in python using numpy

I need to make spectrogram using numpy. I take 1s of audio and split it into 0.02s chunks. Then I calculate FFT using numpy and put it back together into one image. Results are poor. Here is...

### (215:Assertion failed) type == CV_32FC1 || type == CV_32FC2 || type == CV_64FC1 || type == CV_64FC2 in function 'dft'

I am trying to correct exposure in images using fourier. This is the error I am facing 5 padded = np.log(padded + 1) #so we never have log of 0 6 global complex 7 complex =...

### efficiently converting for model.fit

I'm struggling in loading data into model.fit efficiently. My code creates training_data object with samples and values. Samples is a standard python list of objects of tf.Tensor class. Values is...

### No name 'fft' in module 'scipy'

I tried to import FFT from SciPy and got "No name 'fft' in module 'scipy' ". Last time I checked, Scipy did have these modules, so I don't know why I'm getting this error.

### How to find peaks of FFT graph using Python?

I am using Python to perform a Fast Fourier Transform on some data. I then need to extract the locations of the peaks in the transform in the form of the x-values. Right now I am using Scipy's fft...