yt-dlp playlist batch downloader

yt-dlp-batch.py

#!/bin/python3
import yt_dlp
import sys
import time
import multiprocessing

"""
This Script also works on normal playlists
usage: ./<script> <playlist url>

How it works:
    First, it first extracts the urls from playlist into playlist_urls. 
    Then it spawns a number of threads defined by processes variable and maps the processes to playlist_urls

    Notes:
    To change the output, edit outtmpl in ydl-opts{}
    The [None, ... , None] is the error array, if it isnt None, its an error
    This script is barebones, you will have to add other things yourself
"""

args = sys.argv
playlist = args[1]
album_name:str = ''

# number of threads that will spawn 
# change this value accordingly
max_processes=8

ydl_opts_playlist_extractor = {}
ydl_opts = {}

def main():
    ydl_opts_playlist_extractor = {
        'extract_flat': True,
        'skip_download': True,
    }
    ydl_extractor = yt_dlp.YoutubeDL(ydl_opts_playlist_extractor)

    #exits incase an error occurs
    try:
        info_dict = ydl_extractor.extract_info(playlist, download=False, process=False)
    except:
        exit()

    # remove 'Album - ' from playlist name
    global album_name
    album_name = info_dict['title'].replace('Album - ', '')

    playlist_entries = []
    for videos in info_dict['entries']:
        playlist_entries.append(videos)

    playlist_digits = len(str(len(playlist_entries)))

    # get the urls to perform download
    playlist_urls = []
    index = 1
    for video in playlist_entries:
        # create tuples in a list with can be mapped to a multiprocessing pool
        index_zeroed = add_leading_zeros( str(index) , playlist_digits )
        playlist_urls.append( ( index_zeroed , video['url'] ) )
        index += 1

    # creating and mapping thread pool to playlist_urls
    processes = 4
    if len(playlist_entries) > max_processes:
        processes = max_processes
    else:
        processes = len(playlist_entries)

    pool = multiprocessing.Pool(processes=processes)
    outputs = pool.map(ydl_download, playlist_urls)
    print(outputs)

def ydl_download(input: tuple()):
    playlist_index: str = input[0]
    url: str = input[1]
    ydl_opts = {
        'format': 'bestaudio/best',
        # Edit this line to change filenames, extensions, etc.
        'outtmpl': './%(channel)s/' + album_name + '/' + playlist_index + ' %(title)s - %(id)s.mp3'
    }
    # start the download for the process
    with yt_dlp.YoutubeDL(ydl_opts) as  ydl_downloader:
        error = ydl_downloader.download(url)
        return error

def add_leading_zeros(string, length):
    return ("0" * ( length - len(string) ) ) + string

if __name__ == "__main__":
    main()