There are quite a few similar/related questions on SO already which are well worth reading as the answers contain a lot of useful information and advice, but in essence you need to do this: Convert the audio data to the format required by FFT (e.g. int -> float, with separate L/R channels); Apply suitable window … Read more
take a signal, a time-varying voltage v(t) units are V, values are real. throw it into an FFT — ok, you get back a sequence of complex numbers units are still V, values are complex ( not V/Hz – the FFT a DC signal becomes a point at the DC level, not an dirac delta … Read more
The array you are showing is the Fourier Transform coefficients of the audio signal. These coefficients can be used to get the frequency content of the audio. The FFT is defined for complex valued input functions, so the coefficients you get out will be imaginary numbers even though your input is all real values. In … Read more