Make chunks in Audio files with overlap in python

Question

I want to make chunks from my audio files in order to overlap between chunks. For example if each chunks has 4 second length and first chunk start from 0 to 4 and step for overlapping is 1 second, second chunk should be start from 3 to 7.According to this How to splice an audio file (wav format) into 1 sec splices in python? ,I used pydub module for doing this and make_chunks(your_audio_file_object, chunk_length_ms) method, but it doesn't have overlap between chunks and just slice an audio file into fix length chunks. Anyone has an idea for this purpose ? Thank you

Answer 1

Here's one way:

import numpy as np
from scipy.io import wavfile

frequency, signal = wavfile.read(path)

slice_length = 4 # in seconds
overlap = 1 # in seconds
slices = np.arange(0, len(signal)/frequency, slice_length-overlap, dtype=np.int)

for start, end in zip(slices[:-1], slices[1:]):
    start_audio = start * frequency
    end_audio = (end + overlap)* frequency
    audio_slice = signal[int(start_audio): int(end_audio)]

In essence, we do the following:

1. Load file and it's corresponding frequency. For the sake of example I assume its single channel, with multi-channel it would work all the same, just more code.
2. Define desired slice length and overlap. The array will give us start of every audio piece. By zipping it a step further and adding overlap we get desired chunks.

To convince yourself that slicing works, check this snippet:

slice_length = 4 # in seconds
overlap = 1 # in seconds
slices = np.arange(0, 26, slice_length-overlap, dtype=np.int) # 26 is arbitrary

frequency = 1
for start, end in zip(slices[:-1], slices[1:]):
    start_audio = start * frequency
    end_audio = (end + overlap) * frequency 
    print(start_audio, end_audio)

Output:

0 4
3 7
6 10
9 13
12 16
15 19
18 22
21 25