A random partially tested python class file.

Playlist.py

import string, random, subprocess, traceback

class UnSuccesfulCommandExecution(Exception):
    pass

class Playlist:

    playlist = list()
    urls = list()

    def __init__(self, name):
        self.name = name

    def id_generator(self, size=6, chars=string.ascii_uppercase + string.digits):
        return ''.join(random.choice(chars) for _ in range(size))

    def add(self, video_url, local_path):
        video_id = self.id_generator(8)

        if not video_url in self.urls:
            item = {"uid":video_id, "url": video_url, "duration": self.duration(local_path)}
            self.playlist.append(item)
            return item

    def duration(self, path):
        result = subprocess.run(["ffprobe", "-v", "error", "-show_entries",
                             "format=duration", "-of",
                             "default=noprint_wrappers=1:nokey=1", path], 
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT)
        if result.returncode == 0:
            return float(result.stdout)
        else:
            traceback.print_exc()
            raise UnSuccesfulCommandExecution("Error in getting duration. Aborting.")

    def getNext(self, video_id):
        nextItem = None
        for index, item in enumerate(self.playlist):
            if video_id == item["uid"]:
                next_index = index + 1
                if next_index <= len(self.playlist):
                    nextItem = self.playlist[next_index]
                else:
                    nextItem = self.playlist[0]
        return nextItem
    
    def show(self):
        return self.playlist