Python Convert Audio ALAW to PCM Format: A Completed Guide – Python Tutorial

By | October 28, 2021

When we are building voice recognition model, we should convert alaw format audio file to pcm format. In this tutorial, we will introduce you how to convert.

View audio data format

In order to check what is the data format of your audio file, you can use ffprobe application. Here is a tutorial:

View Audio Sample Rate, Data Format PCM or ALAW Using ffprobe – Python Tutorial

How to convert audio alaw to pcm?

We can use python soundfile library.

There are some steps to convert.

Step 1: read audio data

We can use librosa to read. Here is an example:

import librosa
import soundfile as sf

v3 = r'F:\2351349.V3'
audio, sr = librosa.load(v3, sr= c.SAMPLE_RATE, mono=True)

Step 2: save audio data to pcm

Here are PCM_16, PCM_32, you can select one to save.

sf.write('stereo_file.wav', audio, sr, 'PCM_16')

Then we will convert alaw 2351349.V3 to pcm 16 stereo_file.wav

Python Convert Audio ALAW to PCM Format: A Completed Guide - Python Tutorial

Step 3: you use code below to check what formats supported by soundfile

print(sf.available_subtypes('WAV'))

Run this code, you will see:

{'PCM_16': 'Signed 16 bit PCM', 'PCM_24': 'Signed 24 bit PCM', 'PCM_32': 'Signed 32 bit PCM', 'PCM_U8': 'Unsigned 8 bit PCM', 'FLOAT': '32 bit float', 'DOUBLE': '64 bit float', 'ULAW': 'U-Law', 'ALAW': 'A-Law', 'IMA_ADPCM': 'IMA ADPCM', 'MS_ADPCM': 'Microsoft ADPCM', 'GSM610': 'GSM 6.10', 'G721_32': '32kbs G721 ADPCM'}

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