coub-dl/coub-dl.py

from subprocess import call, Popen, PIPE, check_output, DEVNULL
from os import listdir, remove
from os.path import splitext, exists, join
from re import match
from enum import Enum
from datetime import timedelta
from math import floor
from argparse import ArgumentParser
from functools import wraps
from tempfile import TemporaryDirectory



class Stream(Enum):
    AUDIO = 1
    VIDEO = 2

class File(Enum):
    LIST = 1
    LOOP = 2
    FRACTION = 3
    OUTPUT = 4


def call_verbose(before_message='', after_message='Done!'):
    def tag(f):
        @wraps(f)
        def wrapper(*args, **kwargs):
            print_opt(before_message, end='', flush=True)
            f(*args, **kwargs)
            print_opt(after_message)
        return wrapper
    return tag


def print_opt(*args, **kwargs):
    if VERBOSE:
        print(*args, **kwargs)


def get_command_stderr(command):
    process = Popen(command, stderr=PIPE, stdout=PIPE)
    out, err = process.communicate()
    return err


def get_duration(ffprobe_output):
    durationPattern = r'.*Duration:\s(.+),\sstart.*'
    regex = match(durationPattern, str(ffprobe_output))
    duration = regex.groups()[0] if regex else None
    if not duration:
        raise ValueError('Cannot process ffprobe output!')
    return duration


@call_verbose(before_message='Downloading audio stream... ')
def download_audio_stream(url, file_dict):
    call(('youtube-dl', '--ignore-config',
                        '--extract-audio',
                        '--output', '{}.%(ext)s'.format(file_dict[Stream.AUDIO]),
          url),
         stdout=DEVNULL, stderr=DEVNULL)


@call_verbose(before_message='Downloading video stream... ')
def download_video_stream(url, file_dict):
    call(('youtube-dl', '--ignore-config',
                        '--output', '{}.%(ext)s'.format(file_dict[Stream.VIDEO]),
          url),
         stdout=DEVNULL, stderr=DEVNULL)


def read_extensions(file_dict, directory):
    for file in listdir(directory):
        for filename in file_dict:
            fullname = join(directory, file)
            if match('^{}.*'.format(file_dict[filename]), fullname):
                file_dict[filename] = fullname


@call_verbose(before_message='Looping shorter stream... ')
def loop_shorter_stream(file_dict, shorter, shorter_file, loop_fraction):
    # prepare last fractional loop
    call(('ffmpeg', '-i', shorter_file, '-t', str(loop_fraction * shorter.total_seconds()), file_dict[File.FRACTION]),
         stdout=DEVNULL, stderr=DEVNULL)

    # concat them
    call(('ffmpeg', '-f', 'concat', '-safe', '0', '-i', file_dict[File.LIST],
                    '-c', 'copy', file_dict[File.LOOP]),
         stdout=DEVNULL, stderr=DEVNULL)


@call_verbose(before_message='Muxing streams... ')
def mux_streams(file_dict):
    call(('ffmpeg', '-i', file_dict[File.LOOP],
                    '-i', file_dict[Stream.AUDIO],
                    '-map', '0:v:0', '-map', '1:a:0',
                    '-c', 'copy', file_dict[File.OUTPUT]),
         stdout=DEVNULL, stderr=DEVNULL)


def get_length(file):
    data = get_duration(get_command_stderr(('ffprobe', file))).split(':')
    return timedelta(hours=float(data[0]), minutes=float(data[1]), seconds=float(data[2]))


def determine_output_filename(url, user_supplied, extension, files_dict):
    if user_supplied is None:
        files_dict[File.OUTPUT] = check_output(('youtube-dl', '--get-title', url)).decode('utf-8').strip()
    else:
        files_dict[File.OUTPUT] = user_supplied
    files_dict[File.OUTPUT] += extension


def parse_cmd_arguments():
    parser = ArgumentParser(description='Download player-looped videos with youtube-dl & ffmpeg.')
    parser.add_argument('-nv', '--nonverbose', action='store_true', help='Turn off non-critical messages to user.')
    parser.add_argument('-o', '--output', default=None, help='Specify name of the output file (use -e for extension).')
    parser.add_argument('-e', '--extension', default='mp4', help='Set the container to use for the output.')
    parser.add_argument('url', type=str, help='The URL of the site containing the video to download.')

    args = parser.parse_args()
    args.extension = '.' + args.extension

    return args


def yes_no_question(question, default):
    valid = {"yes": True, "y": True, "ye": True,
             "no": False, "n": False}
    if default is None:
        prompt = " [y/n] "
    elif default == "yes":
        prompt = " [Y/n] "
    elif default == "no":
        prompt = " [y/N] "
    else:
        raise ValueError("Invalid default answer: {}!".format(default))

    while True:
        print(question + prompt)
        choice = input().lower()
        if default is not None and choice == '':
            return valid[default]
        elif choice in valid:
            return valid[choice]
        else:
            print("Please respond with 'yes'(y) or 'no'(n)!")


def run(url, files_dict, directory):
    # download streams and update FILE dict with extensions
    download_audio_stream(url, files_dict)
    download_video_stream(url, files_dict)
    read_extensions(files_dict, directory)

    # get stream lengths via ffprobe
    audioLen = get_length(files_dict[Stream.AUDIO])
    videoLen = get_length(files_dict[Stream.VIDEO])

    # decide which stream needs some looping
    longer = audioLen if audioLen > videoLen else videoLen
    shorter = audioLen if audioLen < videoLen else videoLen
    shorterFile = files_dict[Stream.AUDIO] if audioLen < videoLen else files_dict[Stream.VIDEO]
    files_dict[File.LOOP] += splitext(shorterFile)[1]
    files_dict[File.FRACTION] += splitext(shorterFile)[1]

    times = longer.total_seconds() / shorter.total_seconds()
    timesLoop_base = floor(times)
    timesLoop_fraction = times % 1

    # write concat helper file for ffmpeg
    with open(files_dict[File.LIST], 'w') as f:
        for i in range(timesLoop_base):
            print("file '{}'".format(shorterFile), file=f)
        print("file '{}'".format(files_dict[File.FRACTION]), file=f)

    loop_shorter_stream(files_dict, shorter, shorterFile, timesLoop_fraction)
    mux_streams(files_dict)



if __name__ == '__main__':
    args = parse_cmd_arguments()
    VERBOSE = False if args.nonverbose else True

    FILES = {Stream.AUDIO: 'audio', Stream.VIDEO: 'video',
             File.LIST: 'list.txt', File.LOOP: 'loop', File.FRACTION: 'fraction',
             File.OUTPUT: 'output'+args.extension}
    OUTPUT_KEYS = [File.OUTPUT]
    URL = args.url

    determine_output_filename(URL, args.output, args.extension, FILES)

    # ask what to do if output exists
    if exists(FILES[File.OUTPUT]):
        answer = yes_no_question('A file named "{}" already exists! Overwrite?'.format(FILES[File.OUTPUT]),
                                 default='no')
        if not answer:
            print_opt('Exiting!')
            exit()
        else:
            remove(FILES[File.OUTPUT])

    with TemporaryDirectory() as dir:
        # update temporary file locations in FILES dict
        for key in FILES:
            if key not in OUTPUT_KEYS:
                FILES[key] = join(dir, FILES[key])

        run(URL, FILES, dir)