Librosa melspectrogram times don't match actual times in audio file

Question

I\'m trying to calculate MFCC coefficients using librosa.feature, but when I plot it using specshow, times on the specshow graph don\'t match the actual times in my audio file

Answer 1

You should specify the sample rate when using specshow or librosa.feature.mfcc. Otherwise 22050 Hz is assumed. Also, tell librosa, which hop length you have used:

[...]
hop_length = int(WINDOW_HOP * fs)
mel_specgram = librosa.feature.melspectrogram(y[:550], sr=fs,
    n_mels=20, hop_length=hop_length,
    win_length=int(WINDOW_SIZE * fs))

mfcc_s = librosa.feature.mfcc(S=librosa.power_to_db(mel_specgram), n_mfcc=12, sr=fs)

librosa.display.specshow(mfcc_s, x_axis='s', sr=fs, hop_length=hop_length)

These details are essential for proper visualization and not contained in mfcc_s.