Combine multiple videos using ffmpeg concat demuxer

combine_videos_ffmpeg.py

#!/usr/bin/env python3

# Author: Jannis Teunissen
# Inspired by https://gist.github.com/tom-huntington/1323af4b991ca34ef4a46b3e44532ada

import subprocess
from os.path import basename, splitext
from tempfile import NamedTemporaryFile
import argparse


def get_video_metadata(videos):
    """Get ffmpeg metadata for videos

    :param videos: list of videos
    :returns: metadata as a string

    """
    chapters = []
    for i, video in enumerate(videos):
        command = ["ffprobe", "-v", "quiet", "-of", "csv=p=0",
                   "-show_entries", "format=duration",  video]
        output = subprocess.run(command, capture_output=True, text=True)
        stdout = output.stdout.strip()
        duration_us = int(stdout.replace(".", ""))
        title = splitext(basename(video))[0]
        chapters.append({"duration": duration_us,
                         "title": title})

    end = 0
    for i in range(len(videos)):
        chapters[i]["start"] = end + 1
        end = chapters[i]["start"] + chapters[i]["duration"]
        chapters[i]["end"] = end

    metadata = ";FFMETADATA1\n"
    for chapter in chapters:
        metadata += f"""
[CHAPTER]
TIMEBASE=1/1000000
START={chapter["start"]}
END={chapter["end"]}
title={chapter["title"]}
"""
    return metadata


def combine_videos(videos, output_file):
    """Combine several videos into one, including metadata

    :param videos: list of videos
    :param output_file: single output file
    :returns: noting

    """
    metadata = get_video_metadata(videos)

    # With Python 3.12, delete_on_close can be used instead
    with NamedTemporaryFile(mode='wt', delete=False) as tmp_file_list, \
         NamedTemporaryFile(mode='wt', delete=False) as tmp_metadata:

        # Escape single quotes in filenames according to
        # https://www.ffmpeg.org/ffmpeg-utils.html#Quoting-and-escaping
        filelist = ["file '{}'".format(fname.replace("'", r"'\''"))
                    for fname in videos]

        # Write list of files
        tmp_file_list.write('\n'.join(filelist) + '\n')
        tmp_file_list.close()

        # Write metadata
        tmp_metadata.write(metadata)
        tmp_metadata.close()

        command = ["ffmpeg", "-hide_banner", "-y",
                   "-v", "quiet",
                   "-f", "concat",
                   "-safe", "0",
                   "-i", tmp_file_list.name,
                   "-i", tmp_metadata.name,
                   "-map_metadata", "1",
                   "-codec", "copy",
                   output_file]

        output = subprocess.run(command, capture_output=True, text=True)

        if output.stderr:
            raise RuntimeError(output.stderr)


if __name__ == '__main__':
    p = argparse.ArgumentParser(
        description='Combine multiple videos using ffmpeg concat demuxer')
    p.add_argument('-i', required=True, type=str, nargs='+',
                   help='Input videos')
    p.add_argument('-o', required=True, type=str,
                   help='Output video. Will be overwritten if it exists.')
    args = p.parse_args()

    combine_videos(args.i, args.o)