files by chapter concatenated to chapterized file

script.py

import subprocess
import os
import re

def make_chapters_metadata(list_mp4: list):
    print(f"Making metadata source file")

    chapters = {}
    for single_mp4 in list_mp4:
        number = single_mp4.removesuffix(".m4a")
        cmd = f"ffprobe -v quiet -of csv=p=0 -show_entries format=duration '{folder}/{single_mp4}'"
        print(f"{cmd=}")
        duration_in_microseconds_ = subprocess.run(cmd, shell=True, capture_output=True)
        duration_in_microseconds__ = duration_in_microseconds_.stdout.decode().strip().replace(".", "")
        print(f"{duration_in_microseconds_=}")
        duration_in_microseconds = int(duration_in_microseconds__)
        chapters[number] = {"duration": duration_in_microseconds}

    print(f"{chapters=}")
    chapters[list_mp4[0].removesuffix(".m4a")]["start"] = 0
    for n in range(1, len(chapters)):
        chapter = list_mp4[n-1].removesuffix(".m4a")
        next_chapter = list_mp4[n].removesuffix(".m4a")
        chapters[chapter]["end"] = chapters[chapter]["start"] + chapters[chapter]["duration"]
        chapters[next_chapter]["start"] = chapters[chapter]["end"] + 1
    last_chapter = list_mp4[len(chapters)-1].removesuffix(".m4a")
    chapters[last_chapter]["end"] = chapters[last_chapter]["start"] + chapters[last_chapter]["duration"]

    metadatafile = f"{folder}/combined.metadata.txt"
    with open(metadatafile, "w+") as m:
        m.writelines(";FFMETADATA1\n")
        for chapter in chapters:
            ch_meta = """
[CHAPTER]
TIMEBASE=1/1000000
START={}
END={}
title={}
""".format(chapters[chapter]["start"], chapters[chapter]["end"], chapter)
            m.writelines(ch_meta)


def concatenate_all_to_one_with_chapters():
    print(f"Concatenating list of mp4 to combined.mp4")
    metadatafile = f"{folder}/combined.metadata.txt"
    subprocess.run(["ffmpeg", "-hide_banner", "-y", "-safe", "0", "-f", "concat", "-i", "list_mp4.txt", "-c", "copy", "-i", f"{metadatafile}", "-map_metadata", "1", "combined.m4a"])

if __name__ == '__main__':

    folder = "."  # Specify folder where the files 0001.mp4... are
    # concatenate_all_to_one_with_chapters()
    # exit(0)

    list_mp4 = [f for f in os.listdir(folder) if f.endswith('.m4a')]
    list_mp4.sort()
    print(f"{list_mp4=}")

    # Make the list of mp4 in ffmpeg format
    if os.path.isfile("list_mp4.txt"):
        os.remove("list_mp4.txt")
    for filename_mp4 in list_mp4:
        with open("list_mp4.txt", "a") as f:
            line = f"file '{filename_mp4}'\n"
            f.write(line)

    make_chapters_metadata(list_mp4)
    concatenate_all_to_one_with_chapters()