Convert audio in MKV files to AC3. Required Python 3.6

convert.py

import os
import subprocess

all_dir_contents = os.listdir()

mkv_files = [file for file in all_dir_contents if file.endswith('.mkv') and not file.endswith('.converted.mkv') ]

for mkv in mkv_files:
    print('========== Starting  ' + mkv + ' ===========')
    out_file_name = mkv[:-4] + '.converted.mkv'
    
    subprocess.run(['ffmpeg', '-i', mkv, '-map', '0', '-vcodec', 'copy', 
    '-scodec', 'copy', '-acodec', 'ac3', '-b:a', '384k', out_file_name])
    
    subprocess.run(['rm', mkv])
    print('////////// Finished  ' + mkv + ' ///////////')