Change pitch of multiple audio files with Sox

audiofrequencypitchsox

I am intending to take my entire music collection and change the pitch
from the original recorded a=440hz to the more natural sounding/feeling a=432hz.

For those of you who are not familiar with this concept, or the "why" for doing this,
I highly encourage you to do a google search and see what it's all about.
But that is not entirely relevant.

I understand that I could even take Audacity and one-by-one,
convert and re-export the files with the new pitch. I have tried this
and yes, it does work. However, my collection is quite large and I was
excited to find are more fitting command-line option, SOX. Any idea ?

Best Solution

$ sox your_440Hz_music_file.wav your_432Hz_music_file.wav pitch -31

Related Solutions

How to get an audio file sample rate using sox

just use:

soxi <filename>

sox --i <filename>

to produce output such as:

Input File     : 'final.flac'
Channels       : 4
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:00:11.48 = 506179 samples = 860.849 CDDA sectors
File Size      : 2.44M
Bit Rate       : 1.70M
Sample Encoding: 16-bit FLAC
Comment        : 'Comment=Processed by SoX'

The latter one is in case you're using the win32 version that doesn't include soxi, by default. To grab the sample rate only, just use:

soxi -r <filename>

sox --i -r <filename>

which will return the sample rate alone.

Python Audio Frame Pitch Change

After the irfft line, and before the stream.write line, you need to convert the data back into 16-bit integers with a struct.pack call.

data = np.fft.irfft(data)
dataout = np.array(data*0.5, dtype='int16') #undo the *2 that was done at reading
chunkout = struct.pack("%dh"%(len(dataout)), *list(dataout)) #convert back to 16-bit data
stream.write(chunkout)

Best Solution

Related Solutions

How to get an audio file sample rate using sox

Python Audio Frame Pitch Change

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