Hop length

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.

1. What is hop length FFT?
2. How do I choose a hop size?
3. What is N_fft in Librosa?
4. What is a mel spectrogram?

What is hop length FFT?

The hop size (number of samples between each successive FFT window) of Fast Fourier transforms performed is equal to the size of the Fast Fourier transform divided by the overlap factor (e.g. if the frame size is 512 and the overlap is set to 2 then the hop size is 256 samples).

How do I choose a hop size?

Hop size should refer to the number of samples in between successive frames. For signal analysis Hop Size should be less than the frame size, so that frames overlap.

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.

What is a mel spectrogram?

A mel spectrogram logarithmically renders frequencies above a certain threshold (the corner frequency). For example, in the linearly scaled spectrogram, the vertical space between 1,000 and 2,000Hz is half of the vertical space between 2,000Hz and 4,000Hz.