How to convert aac to mp3 in python and maintain the original directory structure

import os
import subprocess
import time
from  import ThreadPoolExecutor, as_completed

def convert_file(input_path, output_path):
    command = [
        'ffmpeg',
        '-y',  # Automatically overwrite existing files        '-i', input_path,
        '-acodec', 'libmp3lame',
        '-b:a', '192k',
        output_path
    ]
    try:
        (command, check=True, stderr=, timeout=300)  #5 minutes timeout        return f"Converted: {output_path}"
    except  as e:
        return f"Error converting {input_path}: {()}"
    except :
        return f"Timeout converting {input_path}"

def convert_aac_to_mp3(input_dir, output_dir):
    start_time = ()
    total_files = 0
    processed_files = 0
    converted_files = 0

    with ThreadPoolExecutor(max_workers=os.cpu_count()) as executor:
        futures = []

        for root, _, files in (input_dir):
            for filename in files:
                if ().endswith('.aac'):
                    total_files += 1
                    input_path = (root, filename)
                    rel_path = (root, input_dir)
                    output_filename = (filename)[0] + '.mp3'
                    output_path = (output_dir, rel_path, output_filename)
                    
                    ((output_path), exist_ok=True)
                    
                    ((convert_file, input_path, output_path))

        for future in as_completed(futures):
            result = ()
            print(result)
            processed_files += 1
            if "Converted" in result:
                converted_files += 1
            print(f"Progress: {processed_files}/{total_files} files processed")

    end_time = ()
    print(f"\nConversion completed.")
    print(f"Total files: {total_files}")
    print(f"Converted files: {converted_files}")
    print(f"Failed conversions: {total_files - converted_files}")
    print(f"Total time: {end_time - start_time:.2f} seconds")

input_dir = input("Please enter the directory path that contains the AAC file: ")
output_dir = input("Please enter the output directory path of the MP3 file: ")
convert_aac_to_mp3(input_dir, output_dir)