I work closely with auditory stimuli. Sometimes I need to convert a large number of audio files from one format to another, usually because different experiment software works better with different audio formats. Here I share my Python script that converts all audio files in a folder from one format to another.

Step 1: Preparation

Install ffmpeg. Remember to put ffmpeg in your PATH.

Install Python (obviously) and pydub: pip install pydub.

Download the Python script (or see full script at the end of this page). Gather all your files in a folder.

Step 2: Run the script

Open convert_audio.py in an IDLE. Modify these variables:

  • AudioSegment.converter: string. Path to your ffmpeg.exe.
  • AudioSegment.ffmpeg: string. Path to your ffmpeg.exe.

  • AudioSegment.ffprobe: string. Path to your ffprobe.exe.

  • dataDir: string. Input folder. Where your original audio files are located.
  • outDir: string. Output folder. Where you want your converted files.
  • input_format: string. Format of your original audio files. Please include ‘.’.
  • output_format: string. Format of your output audio files. Please include ‘.’.

Run the script. Pydub is going to call ffmpeg to convert all files in your chosen folder with the original extension to the output format.

Full script

import os
from pydub import AudioSegment

# set working directory to the python file's directory
os.chdir(os.path.dirname(os.path.abspath(__file__)))

# force pydub to find ffmpeg
AudioSegment.converter = "C:\\ffmpeg\\bin\\ffmpeg.exe"
AudioSegment.ffmpeg = "C:\\ffmpeg\\bin\\ffmpeg.exe"
AudioSegment.ffprobe ="C:\\ffmpeg\\bin\\ffprobe.exe"

# chose input and output folders (where the original files are and where you want to save new files)
dataDir = (os.getcwd() + '/') # input folder
outDir = (os.getcwd()+'/output/') # output folder
if not os.path.exists(outDir):
    os.makedirs(outDir)
print ('Input files are taken from ' + dataDir)
print ('Output files are created in ' + outDir)

# set up input and output formats
input_format = '.mp3'
output_format = '.wav'

dataFileList = os.listdir(dataDir)
for dataFile in dataFileList:
    if dataFile[-(len(input_format)):]==input_format:
        print ('Loading ' + dataFile + '...')
        try:
            sound = AudioSegment.from_file(dataFile)
            outname = outDir + dataFile[:-(len(input_format))] + output_format
            print("Output file: " + outname)
            sound.export(outname, format=output_format[-1:])
        except IOError:
            print('cannot open file ')

print ('Done.')