Why is the number of frequencies decomposed in scipy.signal.stft() equal to the hop size?

1. What is the difference between FFT and STFT?
2. How to calculate STFT in Python?
3. What is hop length in audio?
4. What is N_fft in Librosa?

What is the difference between FFT and STFT?

FFT has a resolution of 2048 lines, Blackman window, and 50% overlap and STFT also has Block size 2048, FFT size 16K, Blackman window used, and 50% overlap. As we can see, STFT performs better with the same block size (but more calculated lines). We improved frequency resolution for the same amount of scooped data.

How to calculate STFT in Python?

STFT Algorithm:

Multiply that segment against a half-cosine function. Pad the end of the segment with zeros. Take the Fourier transform of that segment and normalize it into positive and negative frequencies. Combine the energy from the positive and negative frequencies together, and display the one-sided spectrum.

What is hop length in audio?

Hop length is the length of the non-intersecting portion of window length. Overlap length is the length of the intersecting portion of the window length.

What is N_fft in Librosa?

The default value, n_fft=2048 samples, corresponds to a physical duration of 93 milliseconds at a sample rate of 22050 Hz, i.e. the default sample rate in librosa. This value is well adapted for music signals.