Librosa的采样率问题 [英] Sampling rate issue with Librosa

问题描述

在执行STFT时，然后在具有库

When doing a STFT, and then an inverse STFT (iSTFT) on a 16 bits 44.1 khz audio file with the library Librosa :

import librosa

y, sr = librosa.load('test.wav', mono=False)
y1 = y[0,]
S = librosa.core.stft(y1)
z1 = librosa.core.istft(S, dtype=y1.dtype)
librosa.output.write_wav('test2.wav', z1, sr)

the output is only a 22 khz audio file. Why? Where is there the sampling rate change in librosa ?

解决方案

The librosa.load() function enables target sampling, wherein the audio file you import can be re-sampled to the target sample rate specified by the keyword argument sr.

If you want to use the original sample rate, you have to explicitly set the the target sample rate to None: sr=None. By default, sr=22050, which is why your output is ~22khz.

By way of example:

Default Setting - sub-sampling to default 22,050 Hz

In[51]: filename = librosa.util.example_audio_file()
In[52]: y1, sr1 = librosa.load(filename)
In[53]: print sr1
22050

Explicitly Setting sr=None ensures original sampling preserved

In[54]: y2, sr2 = librosa.load(filename,sr=None)
In[55]: print sr2
44100

Sub-sampling to a specified rate, 16,000 Hz

In[56]: y3, sr3 = librosa.load(filename,sr=16000)
In[57]: print sr3
16000

The result:

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