some question about librosa stft

minwooking

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Feb 23, 2021, 2:02:33 AM2/23/21

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hi.

i want to know the exact frequency range about that stft result.

if sample_rate value set 10000, stft method n_fft parameter set 100,

method result's frequency range is 100Hz?

If what I understand is wrong, please let me know the correct way.

It is difficult to understand because it is my first time analyzing sound.

please, help me.

Brian McFee

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Feb 23, 2021, 9:14:28 AM2/23/21

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If you just want the frequencies corresponding to STFT bands, librosa.fft_frequencies() will compute that for you.

More generally, the discrete Fourier transform is defined by a collection of complex sinusoids (n_fft different frequencies) ranging from f=-sr/2 to f=+sr/2. If your signal is real-valued (as is the case for audio signals), then the negative frequencies are redundant, so we only keep the frequencies f=0, sr/n_fft, 2*sr/n_fft, ... sr/2. This results in a "real" Fourier transform with 1 + n_fft // 2 frequencies, in your case, 0 up to 5000 Hz in increments of 100 Hz (10000 / 100).

minwooking

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Feb 23, 2021, 8:10:28 PM2/23/21

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Thank you for your help Brian.

you saved me

2021년 2월 23일 화요일 오후 11시 14분 28초 UTC+9에 Brian McFee님이 작성:

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