augment_addnoise.py

'''
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Add noise to an audio file.
'''
import os, uuid, random, math
from pydub import AudioSegment

def augment_addnoise(filename,curdir, noisedir):
    if filename[-4:]=='.wav':
        audioseg=AudioSegment.from_wav(filename)
    elif filename[-4:]=='.mp3':
        audioseg=AudioSegment.from_mp3(filename)
    hostdir=os.getcwd()
    os.chdir(curdir)
    os.chdir(noisedir)
    listdir=os.listdir()
    if 'noise.wav' in listdir:
        os.remove('noise.wav')
    mp3files=list()
    for i in range(len(listdir)):
        if listdir[i][-4:]=='.mp3':
            mp3files.append(listdir[i])
    noise=random.choice(mp3files)
    # add noise to the regular file 
    noise_seg = AudioSegment.from_mp3(noise)
    # find number of noise segments needed
    cuts=math.floor(len(audioseg)/len(noise_seg))
    noise_seg_2=noise_seg * cuts
    noise_seg_3=noise_seg[:(len(audioseg)-len(noise_seg_2))] 
    noise_seg_4=noise_seg_2 + noise_seg_3
    os.chdir(hostdir)
    print(len(noise_seg_4))
    print(len(audioseg))
    noise_seg_4.export("noise.wav", format="wav")
    # now combine audio file and noise file 
    newfile=filename[0:-4]+'_noise.wav'
    os.system('ffmpeg -i %s -i %s -filter_complex "[0:a][1:a]join=inputs=2:channel_layout=stereo[a]" -map "[a]" %s'%(filename, 'noise.wav',newfile))
    os.remove('noise.wav')
    return [filename, newfile]