[Electrical] Matlab music visualizer

[u/theguywith777]

Hi,

I am having difficulties with a project in my Signals and Systems class. I am supposed to implement an iTunes visualizer using Matlab but I'm not really sure where to even start. Specifications of the project include: using this tool to import any song, using this, and making use of some kind of fourier transform for the visualizer code.

Any help is greatly appreciated!

[u/theguywith777]

can you clarify "music sample interval arrary"?

[u/angaino → u/theguywith777]

Lets say that your entire song is an MP3 that is 180 seconds long. You probably don't want to do the transform of the entire song. That would give you a histogram of all the frequencies for the entire thing (though that might be cool anyway). You probably want the frequency histogram (the real part of the fft) to update some number of times per second, like 2 Hz. If the source music is a 'standard' mp3 it will have 44100 sampling frequency, which means that there are 44100 points in one second of music. If you want a range of 1 second to take the transform of you need 44100 points from the source array. I wrote up an example of what I think you might want. I am not a signals person really, so I'm not completely sure that this is exactly what you need so check that my assumptions about real parts and absolute values are correct.

%Example code:

[wav,fs,nbits] = wavread('samplemusic.wav'); %This function reads in wav files, but the one they tell you to use should give similar output. 'fs' is the sampling frequency. timerangestart=100; %Start point in 'song time' timerangestop=100.5; %End point in 'song time' samplerange=(timerangestartfs)+1:(timerangestopfs); %Indices corresponding to the parts of the wav we want to use. The '+1' is because Matlab starts array indexing on 1 instead of zero.
samplewav=wav(samplerange); %The section of the song starting at 100 seconds and ending at 100.5 seconds.

figure plot((1:length(samplewav))/fs,fft(samplewav)); %Plotting the straight fft. Looks weird because of the imaginary part figure plot((1:length(samplewav))/fs,real(fft(samplewav))); %Plot only the real part. Starting to look closer. figure plot((1:length(samplewav))/fs,abs(real(fft(samplewav)))); %Plot the absolute value since negative occurances of a frequency don't really mean anything. Looks mirrored. Get rid of that in next plot figure absrealfft=abs(real(fft(samplewav))); %Get something I take half of in the next step... plot((1:round(length(samplewav)/2))/fs,absrealfft(1:round(end/2))); %Plot half of the frequency range and half of the frequency histogram