spectrum

I want to plot the frequency spectrum of a music file (like they do for example in Audacity). Hence I want the frequency in Hertz on the x-axis and the amplitude (or desibel) on the y-axis. I devide the song (about 20 million samples) into blocks of 4096 samples at a time. These blocks will result in 2049 (N/2 + 1) complex numbers (sine and cosine -> real and imaginary part). So now I have these thousands of individual 2049-arrays, how do I combine them? Lets say I do the FFT 5000 times resulting in 5000 2049-arrays of complex numbers. Do I plus all the values of the 5000 arrays and then take

I have a list of RGB triplets, and I'd like to plot them in such a way that they form something like a spectrum. I've converted them to HSV, which people seem to recommend. from PIL import Image, ImageDraw import colorsys def make_rainbow_rgb(colors, width, height): """colors is an array of RGB tuples, with values between 0 and 255""" img = Image.new("RGBA", (width, height)) canvas = ImageDraw.Draw(img) def hsl(x): to_float = lambda x : x / 255.0 (r, g, b) = map(to_float, x) h, s, l = colorsys.rgb_to_hsv(r,g,b) h = h if 0 < h else 1 # 0 -> 1 return h, s, l rainbow = sorted(colors, key=hsl) dx

I've read these question: Using the Apple FFT and Accelerate Framework How do I set up a buffer when doing an FFT using the Accelerate framework? iOS FFT Accerelate.framework draw spectrum during playback They all describe how to setup fft with the accelerate framework. With their help I was able to setup fft and get a basic spectrum analyzer. Right now, I'm displaying all values I got from the fft. However, I only want to show 10-15, or a variable number, of bars respreseting certain frequencies. Just like the iTunes or WinAmp Level Meter. 1. Do I need to average magnitude values from a range

I already have the program of the player, wave form generator, spectrum analyzer, the list box where the time will be recorded. These stuffs are working. Now, I want to add the feature, when you will play the audio file, and it reached the certain threshold or the max peak of the spectrum, the time of that current event will be recorded to the list box. I managed to add time in the list box so now, my only problem is how to detect the event. I used FFT in the spectrum analyzer, but I;m stuck on this. How can I do this using my current resources like FFT, waveform generator, spectrum analyzer,

I'm trying to verify an FFT algorithm I should use for a project VS the same thing on Matlab. The point is that with my own C FFT function I always get the right (the second one) part of the double sided FFT spectrum evaluated in Matlab and not the first one as "expected". For instance if my third bin is in the form a+i*b the third bin of Matlab's FFT is a-i*b. A and b values are the same but i always get the complex conjugate of Matlab's. I know that in terms of amplitudes and power there's no trouble (cause abs value) but I wonder if in terms of phases I'm going to read always wrong angles.

I have a spectral data (1000 variables on xaxis, and peak intensities as y) and a list of peaks of interest at various specific x locations (a matrix called Peak) which I obtained from a function I made. Here, I would like to draw a line from the maximum value of each peaks to the xaxis - or, eventually, place a vertical arrow above each peaks but I read it is quite troublesome, so just a vertical line is welcome. However, using the following code, I get "Error using line Value must be a vector of numeric type". Any thoughts? X = spectra; [Peak,intensity]=PeakDetection(X); nrow = length(Peak);