Burn .ass subs to video for an entire directory.

burnsubs.py

#!/usr/bin/python

"""
Usage: python burnsubs.py <source> <destination>

This script extracts ass subs from all mkv videos in a source directory then
burns them to the video and outputs it to the destination directory. 
Ffmpeg is required. There are some unix specific commands in the script but
it shouldn't be too difficult to adapt to windows.
"""

import subprocess
from random import randrange
from pathlib import Path
from sys import argv


def main():
    if len(argv) != 3:
        print_help()
        return

    source = Path(argv[1])
    destination = Path(argv[2])

    if not source.is_dir() or (destination.exists() and
                               not destination.is_dir()):
        print_help()
        return

    subs_dir = extract_subs(source)
    try:
        burn_subs(source, destination, subs_dir)
    finally:
        subprocess.run(['rm', '-r', str(subs_dir)])  # the rm command is unix specific.


def print_help():
    print("Usage: python burnsubs.py <source_directory> <destination_directory>")  # noqa


def extract_subs(source: Path):
    sub_dir = Path(f'/tmp/extracted_ass-{randrange(999)}')
    while sub_dir.exists():
        sub_dir = Path(f'/tmp/extracted_ass-{randrange(999)}')  # /tmp is unix specific. Change to C:\Windows\Temp for windows.
    sub_dir.mkdir()

    vids = list(source.glob('*.mkv'))

    print("Extracting ass...")  # hehe
    for i, vid in enumerate(vids):
        ass_path = sub_dir / (vid.stem + '.ass')
        subprocess.run(['ffmpeg', '-loglevel', '-8', '-i',
                        str(vid), str(ass_path)]).check_returncode()
        print(f'{i+1}/{len(list(vids))}')

    print(f"    Finished extracting subs to {sub_dir}.")
    return sub_dir


def burn_subs(source: Path, destination: Path, subs: Path):
    if not destination.exists():
        destination.mkdir()

    # Here you can specify file type.
    vids = list(source.glob('*.mkv'))

    print("\nBurning subs...")
    for i, vid in enumerate(vids):
        out = destination/('incomplete' + vid.suffix)

        # Feel free to play with ffmpeg settings. Change ultrafast to superfast/fast for
        # better but slower compression. Change tune from animation to anything else
        # depending on needs.
        subprocess.run(['ffmpeg', '-i', str(vid),
                        '-vf', f"ass='{subs/(vid.stem+'.ass')}",
                        '-preset', 'ultrafast', '-tune', 'animation',
                        str(out)]).check_returncode()

        out.rename(out.parent/vid.name)

        print(f'{i+1}/{len(list(vids))}')


if __name__ == '__main__':
    main()