How to extract frequency information from samples from PortAudio using FFTW in C

Question

I want to make a program that would record audio data using PortAudio (I have this part done) and then display the frequency information of that recorded audio (for now, I\'

Answer 1

To convert your audio samples to a power spectrum:

• if your audio data is integer data then convert it to floating point
• pick an FFT size (e.g. N=1024)
• apply a window function to N samples of your data (e.g. Hanning)
• use a real-to-complex FFT of size N to generate frequency domain data
• calculate the magnitude of your complex frequency domain data (magnitude = sqrt(re^2 + im^2))
• optionally convert magnitude to a log scale (dB) (magnitude_dB = 20*log10(magnitude))