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Last active October 24, 2023 20:36
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A python script to take a bunch of session stems and mix them down for quick reference listening
# For when you have a cigar box of SD cards that get dumped onto an external hard drive
import argparse
from pydub import AudioSegment
from pydub.effects import normalize, compress_dynamic_range
import os
from multiprocessing import Pool
# Define the root directory where your audio stems are located
root_directory = "/Volumes/HD1-B/2023"
# Function to mix down stems in a folder and apply mastering effects
def mix_and_master_stems_in_folder(folder_path):
# Create an empty AudioSegment to hold the mix
mix = AudioSegment.silent(duration=0)
# Iterate through files in the folder
for file_name in os.listdir(folder_path):
# Check if the file has a ".wav" extension (case-insensitive)
if file_name.lower().endswith(".wav"):
# Load the stem audio file
stem = AudioSegment.from_wav(os.path.join(folder_path, file_name))
# Mix it with the existing mix
mix = mix + stem
# Apply mastering effects
mix = normalize(mix) # Normalize the audio
mix = compress_dynamic_range(mix, threshold=-20.0, ratio=2.0) # Apply compression (adjust threshold and ratio as needed)
return mix
# Function to check if a file already exists and remove it if needed
def check_and_remove_if_exists(file_path, remove_preexisting):
if os.path.exists(file_path):
if remove_preexisting:
print(f"Skipping '{file_path}' as requested.")
return False
return True
def process_session(datestamped_folder, remove_preexisting, skip_preexisting, destination_path):
folder_path = os.path.join(root_directory, datestamped_folder)
if os.path.isdir(folder_path):
if skip_preexisting:
# If skipping preexisting, check if the files already exist and skip the processing
wav_output_path = os.path.join(destination_path, f"{datestamped_folder}-mixed.wav")
mp3_output_path = os.path.join(destination_path, f"{datestamped_folder}-mixed.mp3")
if os.path.exists(wav_output_path) and os.path.exists(mp3_output_path):
print(f"Skipping '{datestamped_folder}' as requested.")
# Mix and master the stems for each session
session_mix = mix_and_master_stems_in_folder(folder_path)
# Create the output file paths with the datestamp in the destination folder
wav_output_path = os.path.join(destination_path, f"{datestamped_folder}-mixed.wav")
mp3_output_path = os.path.join(destination_path, f"{datestamped_folder}-mixed.mp3")
# If the files already exist, check and remove or skip based on the arguments
if remove_preexisting:
check_and_remove_if_exists(wav_output_path, True)
check_and_remove_if_exists(mp3_output_path, True)
# Export the mixed and mastered session as WAV and MP3 files
session_mix.export(wav_output_path, format="wav")
session_mix.export(mp3_output_path, format="mp3")
print(f"Mixed and mastered {datestamped_folder} and saved as {wav_output_path} and {mp3_output_path}")
def main():
# Create an argument parser
parser = argparse.ArgumentParser(description="Mix and master audio stems")
# Add a flag to remove preexisting files
parser.add_argument("--remove-preexisting", action="store_true", help="Remove preexisting mixed audio files if they exist")
# Add a flag to skip preexisting files
parser.add_argument("--skip-preexisting", action="store_true", help="Skip processing of preexisting mixed audio files")
# Add an optional parameter for a specific folder name
parser.add_argument("--folder-name", type=str, help="Process a specific folder by name")
# Add an optional parameter for the destination path
parser.add_argument("--destination-path", type=str, help="Specify the destination path for exported files")
# Add an option to specify the number of processes
parser.add_argument("--num-processes", type=int, default=4, help="Number of processes to use for parallel processing (default: 4)")
args = parser.parse_args()
# Get the list of datestamped folders
datestamped_folders = [folder for folder in os.listdir(root_directory) if os.path.isdir(os.path.join(root_directory, folder))]
# If a specific folder name is provided, process only that folder
if args.folder_name:
if args.folder_name in datestamped_folders:
datestamped_folders = [args.folder_name]
print(f"Folder '{args.folder_name}' not found in the root directory.")
# Process each session in parallel with the specified number of processes
with Pool(processes=args.num_processes) as pool:
# Pass the destination path to the process_session function
pool.starmap(process_session, [(folder, args.remove_preexisting, args.skip_preexisting, args.destination_path) for folder in datestamped_folders])
if __name__ == "__main__":
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Audio Mixing and Mastering Script

This Python script allows you to mix and master audio stems, providing a convenient way to combine multiple audio tracks and apply mastering effects. It supports processing audio sessions stored in date-stamped folders and provides options for managing preexisting mixed audio files and specifying a destination path for the exported files.


Before running this script, make sure you have the following:

  • Python 3.x installed on your system.


Running the Script

To use the script, follow these steps:

  1. Clone or download this repository to your local machine.

  2. Open a terminal or command prompt.

  3. Navigate to the directory containing the script using the cd command.

  4. Run the script with the desired options. Here are the available command-line options:

    • --remove-preexisting: Remove preexisting mixed audio files if they exist.
    • --skip-preexisting: Skip processing of preexisting mixed audio files.
    • --folder-name: Process a specific folder by name.
    • --destination-path: Specify the destination path for exported files.
    • --num-processes: Number of processes to use for parallel processing (default: 4).

    Example usage:

    python --remove-preexisting --destination-path /path/to/export

Input Audio

The script expects audio stems to be organized within date-stamped folders, typically within a root directory. For example:

   ├── 210801_062039/
   │     ├── audio_1.wav
   │     ├── audio_2.wav
   │     ├── ...
   ├── 210802_071520/
   │     ├── audio_1.wav
   │     ├── audio_2.wav
   │     ├── ...
   ├── ...


The script will mix and master the audio stems, and the resulting mixed audio files will be saved in the specified destination-path or the same folder as the original stems.

Example Command

python --remove-preexisting --destination-path /path/to/export


  • Make sure to configure the script by setting the root_directory variable in the script to the root directory containing your audio stems.

  • You can adjust the mastering effects in the script to suit your preferences.

  • This script uses the pydub library for audio processing.


This script is provided under the MIT License. See LICENSE for details.

You can replace placeholders like /path/to/export with actual file paths or adjust the content to fit your specific script and use case.

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