A simple script that auto-renames my chosen files and folders (after having downloaded them from bandcamp) to standardize them for my music library

Bandcamp auto-renamer

import os
import mutagen
import sys

# function to find nth occurence of needle in haystack
def find_nth(haystack, needle, n):
    start = haystack.find(needle)
    while start >= 0 and n > 1:
        start = haystack.find(needle, start+len(needle))
        n -= 1
    return start

# function to validate the user input
def choice_validation(choice, list_len):
    if choice == 'q' or choice == 'Q':
        sys.exit()
    try:
        choice = int(choice)
    except:
        raise ValueError('An integer was expected. Please make sure to enter an integer as input.')
    if choice < 0 or choice > list_len:
	    raise ValueError('Please restrict your choice to an integer between 0 and ' + str(list_len))
    else:
        return(choice)

# function to create list of subdirectories of chosen directory
def list_directories(root):
    dir_list = []
    for dir in os.listdir(root):
        if os.path.isdir(os.path.join(root, dir)):
            dir_list.append(dir)
    return(dir_list)

# function to print the list of subdirectories of chosen directory as a menu
def print_directories(dir_list):
    print('\nIn the Downloads directory, we found the following subdirectories:')
    for i in range(len(dir_list)):
        print('[' + str(i) + ']:\t' + dir_list[i])
    print('[' + str(len(dir_list)) + ']:\tAll')
    print('[Q]\tExit')

# function to rename the files
def rename_files(path):
    for filename in os.listdir(path):
        if find_nth(filename, ' - ', 2) >= 0:
            os.rename(os.path.join(path, filename), os.path.join(path, filename[find_nth(filename, ' - ', 2) + 3:]))
        else:
            continue

# function to rename the directories
def rename_dir(path):
    audiofile = [afile for afile in os.listdir(path) if afile.startswith('01')][0]
    audiomut = mutagen.File(os.path.join(path, audiofile))

    # get the year of album release
    try: # for flac
        year = audiomut['date'][0]
    except KeyError: # for mp3
        year = audiomut['TDRC'][0]

    # get the extension
    ext = os.path.splitext(audiofile)[1][1:].upper()
    if ext == 'MP3':
        if audiomut.info.bitrate / 1000 == 320:
            ext = '320'
        else:
            ext = 'V0'

    # rename the directory accordingly
    if path.find('(') >= 0:
        new_path = path[:len(path) - (len(path) - path.find('('))] + ' (' + str(year) + ') [WEB ' + ext + ']'
    else:
        new_path = path + ' (' + str(year) + ') [WEB ' + ext.upper() + ']'
    os.rename(path, new_path)



root = r'C:\Users\NAME\Downloads\'
dir_list = list_directories(root)
print_directories(dir_list)

choice = choice_validation(input('\nWhich (sub)directory do you want to run this renaming script on?: '), len(dir_list))

if choice == len(dir_list):
    for dirr in dir_list:
        rename_files(os.path.join(root, dirr))
        rename_dir(os.path.join(root, dirr))
else:
    rename_files(os.path.join(root, dir_list[choice]))
    rename_dir(os.path.join(root, dir_list[choice]))

print('\nDone.')