Create chapters in a video using ffmpeg+python

vidchapper.py

import sys
import subprocess
import re

argslen = len(sys.argv)

vidfile = sys.argv[1]
chapfile = sys.argv[2]
mdfile = 'mdfile.txt'

subprocess.call(['ffmpeg', '-y', '-v', 'error', '-i', vidfile, '-f', 'ffmetadata', mdfile])

outsub = subprocess.check_output(['ffprobe', '-v', 'error',\
         '-show_entries', 'format=duration',\
         '-of', 'default=noprint_wrappers=1:nokey=1',\
         vidfile]).decode()

endts = float(outsub.strip())

print(f'Reading chapters from {chapfile}...')

chapdata = []
with open(chapfile, 'r') as f:
    for line in f:
        ts, cname = line.split(" ", 1)
        tsparts = list(filter(None, re.split("[.:]+", ts)))
        tsargs = len(tsparts)

        multiplier = 1
        tss = 0
        # Check if milliseconds argument given
        if(ts.find('.') != -1):
            tsms = float(tsparts[-1])
            for part in range(2, tsargs + 1):
                tss += multiplier * float(tsparts[-part])
                multiplier *= 60
            tsms = 1000 * tss + tsms
        else:
            for part in range(1, tsargs + 1):
                tss += multiplier * float(tsparts[-part])
                multiplier *= 60
            tsms = 1000 * tss

        chapdata.append([int(tsms), cname])

chapnum = len(chapdata)
chaptext = ""

for i in range(chapnum):
    cstart = chapdata[i][0]
    if (i < (chapnum - 1)):
        cend = chapdata[i+1][0] - 1
    else:
        cend = int(1000 * endts)
    cname = chapdata[i][1]
    chaptext += f"""
[CHAPTER]
TIMEBASE=1/1000
START={cstart}
END={cend}
title={cname}"""

with open(mdfile, 'a') as f:
    f.write(chaptext)

vidfilename, vidfileformat = vidfile.split('.', 1)
modvidfile = vidfilename + '_wch.' + vidfileformat
outstatus = subprocess.run(['ffmpeg', '-loglevel', 'error', '-stats', '-i', vidfile, '-i', mdfile,\
           '-map_metadata', '1', '-codec', 'copy',\
           modvidfile])

if (outstatus.returncode == 0):
    print(f'Chapters successfully written to {modvidfile}!')

This short, crude script takes in as argument

• a video file anyvideo.ext
• a text file with chapters anyname.txt
  like so:

python vidchapper.py anyvideo.ext anyname.txt

You need to have python installed (of course, silly!), and ffmpeg: it should also be added to path.

To view chapters, you need a suitable player. VLC is able to display chapters - I don't know of any other (yet).

---

Chapters text file should be in the format:

hh:mm:ss.mls chapname1
hh:mm:ss:mls chapname2
.
.

hh, mm, mls stand for hours, minutes, milliseconds respectively and are optional, depending on your requirement and the length of the video. ss stands for seconds and should always be provided, even if 0. The separators are important.

Sample chapter file:

9:30 Hello World
10:57.348 Bye World