Create video chapter metadata script

metadata.py

"""Create a Metadata file with chapters for a Video

Usage:
    * Place a `chapter.txt` file in the same directory as the video file.
    with the following format:

        00:00:00 Chapter 1
        00:00:00 Chapter 2
        ...
    
    * Running the script will create a `metadata.txt` file in the same directory

    `python metadata.py`

    * The `metadata.txt` file can be used with `ffmpeg` to add chapters to the Video

    `ffmpeg -i input.mp4 -i metadata.txt -map_metadata 1 -c copy output.mp4`
"""

import re

chapters = list()

with open("chapters.txt", "r") as f:
    for line in f:
        x = re.match(r"(\d):(\d{1,2}):(\d{2}) (.*)", line)
        assert x is not None
        hrs = int(x.group(1))
        mins = int(x.group(2))
        secs = int(x.group(3))
        title = x.group(4)

        minutes = (hrs * 60) + mins
        seconds = secs + (minutes * 60)
        timestamp = seconds * 1000
        chap = {"title": title, "startTime": timestamp}
        chapters.append(chap)

text = ""

chapter_format = """
[CHAPTER]
TIMEBASE=1/1000
START={}
END={}
title={}
"""

for i in range(len(chapters) - 1):
    chap = chapters[i]
    title = chap["title"]
    start = chap["startTime"]
    end = chapters[i + 1]["startTime"] - 1

    try:
        assert end > start
        text += chapter_format.format(start, end, title)

    except AssertionError:
        print(f"Skipping {title} because end time is before start time")


with open("metadata.txt", "a") as myfile:
    myfile.write(text)