Is there an elegant way to split a file by chapter using ffmpeg?

Question

In this page, Albert Armea share a code to split videos by chapter using ffmpeg. The code is straight forward, but not quite good-looking.

ffmpeg -i "$SOURCE.$EXT" 2>&1 |
grep Chapter |
sed -E "s/ *Chapter #([0-9]+\.[0-9]+): start ([0-9]+\.[0-9]+), end ([0-9]+\.[0-9]+)/-i \"$SOURCE.$EXT\" -vcodec copy -acodec copy -ss \2 -to \3 \"$SOURCE-\1.$EXT\"/" |
xargs -n 11 ffmpeg

Is there an elegant way to do this job?

Clubbable

I had to make a slight modification to get that working because my chapters had the word "Chapter" in the title: | grep '^\s*Chapter' | – Spense

I'd like to know how to do the opposite: concat files with chapter markers added for each file. – Helbonia

Looks like we have to script it. We need a shortcut to rip vdeos like those from youtube .mkv with chapters, to multiple sound files. – Chapple

Answer 1

(Edit: This tip came from https://github.com/phiresky via this issue: https://github.com/harryjackson/ffmpeg_split/issues/2)

You can get chapters using:

ffprobe -i fname -print_format json -show_chapters -loglevel error

If I was writing this again I'd use ffprobe's json options

(Original answer follows)

This is a working python script. I tested it on several videos and it worked well. Python isn't my first language but I noticed you use it so I figure writing it in Python might make more sense. I've added it to Github. If you want to improve please submit pull requests.

#!/usr/bin/env python
import os
import re
import subprocess as sp
from subprocess import *
from optparse import OptionParser

def parseChapters(filename):
  chapters = []
  command = [ "ffmpeg", '-i', filename]
  output = ""
  try:
    # ffmpeg requires an output file and so it errors 
    # when it does not get one so we need to capture stderr, 
    # not stdout.
    output = sp.check_output(command, stderr=sp.STDOUT, universal_newlines=True)
  except CalledProcessError, e:
    output = e.output 
   
  for line in iter(output.splitlines()):
    m = re.match(r".*Chapter #(\d+:\d+): start (\d+\.\d+), end (\d+\.\d+).*", line)
    num = 0 
    if m != None:
      chapters.append({ "name": m.group(1), "start": m.group(2), "end": m.group(3)})
      num += 1
  return chapters

def getChapters():
  parser = OptionParser(usage="usage: %prog [options] filename", version="%prog 1.0")
  parser.add_option("-f", "--file",dest="infile", help="Input File", metavar="FILE")
  (options, args) = parser.parse_args()
  if not options.infile:
    parser.error('Filename required')
  chapters = parseChapters(options.infile)
  fbase, fext = os.path.splitext(options.infile)
  for chap in chapters:
    print "start:" +  chap['start']
    chap['outfile'] = fbase + "-ch-"+ chap['name'] + fext
    chap['origfile'] = options.infile
    print chap['outfile']
  return chapters

def convertChapters(chapters):
  for chap in chapters:
    print "start:" +  chap['start']
    print chap
    command = [
        "ffmpeg", '-i', chap['origfile'],
        '-vcodec', 'copy',
        '-acodec', 'copy',
        '-ss', chap['start'],
        '-to', chap['end'],
        chap['outfile']]
    output = ""
    try:
      # ffmpeg requires an output file and so it errors 
      # when it does not get one
      output = sp.check_output(command, stderr=sp.STDOUT, universal_newlines=True)
    except CalledProcessError, e:
      output = e.output
      raise RuntimeError("command '{}' return with error (code {}): {}".format(e.cmd, e.returncode, e.output))

if __name__ == '__main__':
  chapters = getChapters()
  convertChapters(chapters)

Academic

Here's another similar python script meant to parse m4b audio books by chapters. github.com/valekhz/m4b-converter – Carleycarli

I posted a modified version below that uses the chapter name as the filename. It's not elegant but it works :) – Covenanter

and a second one, written this one just now for AAX to MP3 chapterized conversion github.com/OndrejSkalicka/aax-to-mp3-python – Margemargeaux

Confirmed: It does work, and thank you for making it available! – Elkeelkhound

Great basis for what I need. I want to edit out some stuff by chapter name and then recombine them afterwards but I can see how to do that easy enough. – Bindery

@Crissov I rejected you're edit by mistake, can you please add it back so you get the credit for it ie stackoverflow.com/review/suggested-edits/24746850 – Academic

The json from the ffprobe output has been invaluable recently. Admittedly, I have not taken advantage of the python script. Very helpful, thank you. – Nogood

Answer 2

A version of the original shell code with:

• improved efficiency by
  • using ffprobe instead of ffmpeg
  • splitting the input rather than the output
• improved reliability by avoiding xargs and sed
• improved readability by using multiple lines
• carrying over of multiple audio or subtitle streams
• remove chapters from output files (as they would be invalid timecodes)
• simplified command-line arguments

#!/bin/sh -efu

input="$1"
ffprobe \
    -print_format csv \
    -show_chapters \
    "$input" |
cut -d ',' -f '5,7,8' |
while IFS=, read start end chapter
do
    ffmpeg \
        -nostdin \
        -ss "$start" -to "$end" \
        -i "$input" \
        -c copy \
        -map 0 \
        -map_chapters -1 \
        "${input%.*}-$chapter.${input##*.}"
done

To prevent it from interfering with the loop, ffmpeg is instructed not to read from stdin.

Euchology

You can use -nostdin instead of </dev/null, -c copy instead of -vcodec copy -acodec copy -scodec copy, and -map 0 instead of -map 0:a -map 0:v -map 0:s. – Issy

I'd also move the line -ss ... before the line -i ..., otherwise ffmpeg builds the output file in order to seek rather than seeking directly in the input. This speeds up things immensely when you're also transcoding. Depending on what you're splitting you may not want to do this (I'm splitting and transcoding audio so seeking the input is fine). – Gelignite

@Issy @Gelignite great suggestions, thank you! If you have jq at hand, I'd actually recommend @SebMa's answer which appears to be based on mine, but much more future proof thanks to using ffprobe's JSON output. But I'll incorporate your tips anyway. – Euchology

This one puts all but the previous chapter informations in all files ie. 1..23 in the first, 2..23 in the second and so on – Thanasi

Answer 3

ffmpeg -i "$SOURCE.$EXT" 2>&1 \ # get metadata about file
| grep Chapter \ # search for Chapter in metadata and pass the results
| sed -E "s/ *Chapter #([0-9]+.[0-9]+): start ([0-9]+.[0-9]+), end ([0-9]+.[0-9]+)/-i \"$SOURCE.$EXT\" -vcodec copy -acodec copy -ss \2 -to \3 \"$SOURCE-\1.$EXT\"/" \ # filter the results, explicitly defining the timecode markers for each chapter
| xargs -n 11 ffmpeg # construct argument list with maximum of 11 arguments and execute ffmpeg

Your command parses through the files metadata and reads out the timecode markers for each chapter. You could do this manually for each chapter..

ffmpeg -i ORIGINALFILE.mp4 -acodec copy -vcodec copy -ss 0 -t 00:15:00 OUTFILE-1.mp4

or you can write out the chapter markers and run through them with this bash script which is just a little easier to read..

#!/bin/bash
# Author: http://crunchbang.org/forums/viewtopic.php?id=38748#p414992
# m4bronto

#     Chapter #0:0: start 0.000000, end 1290.013333
#       first   _     _     start    _     end

while [ $# -gt 0 ]; do

ffmpeg -i "$1" 2> tmp.txt

while read -r first _ _ start _ end; do
  if [[ $first = Chapter ]]; then
    read  # discard line with Metadata:
    read _ _ chapter

    ffmpeg -vsync 2 -i "$1" -ss "${start%?}" -to "$end" -vn -ar 44100 -ac 2 -ab 128  -f mp3 "$chapter.mp3" </dev/null

  fi
done <tmp.txt

rm tmp.txt

shift
done

or you can use HandbrakeCLI, as originally mentioned in this post, this example extracts chapter 3 to 3.mkv

HandBrakeCLI -c 3 -i originalfile.mkv -o 3.mkv

or another tool is mentioned in this post

mkvmerge -o output.mkv --split chapters:all input.mkv

Carleycarli

Upvote for mkvmerge. One liner to get all chapters that even works with windows 👍 – Liquorish

mkvmerge can also take input (maybe even output) in other formats. Used with m4v and m4b just fine. – Wenz

Answer 4

A little more simple than extracting data with sed by using JSON with jq :

#!/usr/bin/env bash 
# For systems where "bash" in not in "/bin/"

set -efu

videoFile="$1"
ffprobe -hide_banner \
        "$videoFile" \
        -print_format json \
        -show_chapters \
        -loglevel error |
    jq -r '.chapters[] | [ .id, .start_time, .end_time | tostring ] | join(" ")' |
    while read chapter start end; do
        ffmpeg -nostdin \
               -ss "$start" -to "$end" \
               -i "$videoFile" \
               -map 0 \
               -map_chapters -1 \
               -c copy \
               -metadata title="$chapter"
               "${videoFile%.*}-$chapter.${videoFile##*.}";
    done

I use the tostring jq function because chapers[].id is an integer.

Gurolinick

Answer 5

This is the PowerShell version

$filePath = 'C:\InputVideo.mp4'

$file = Get-Item $filePath

$json = ConvertFrom-Json (ffprobe -i $filePath -print_format json -show_chapters -loglevel error | Out-String)

foreach($chapter in $json.chapters)
{
    ffmpeg -loglevel error -i $filePath -c copy -ss $chapter.start_time -to $chapter.end_time "$($file.DirectoryName)\$($chapter.id).$($file.Extension)"
}

Understood

Answer 6

I modified Harry's script to use the chapter name for the filename. It outputs into a new directory with the name of the input file (minus extension). It also prefixes each chapter name with "1 - ", "2 - ", etc in case there are chapters with the same name.

#!/usr/bin/env python
import os
import re
import pprint
import sys
import subprocess as sp
from os.path import basename
from subprocess import *
from optparse import OptionParser

def parseChapters(filename):
  chapters = []
  command = [ "ffmpeg", '-i', filename]
  output = ""
  m = None
  title = None
  chapter_match = None
  try:
    # ffmpeg requires an output file and so it errors
    # when it does not get one so we need to capture stderr,
    # not stdout.
    output = sp.check_output(command, stderr=sp.STDOUT, universal_newlines=True)
  except CalledProcessError, e:
    output = e.output

  num = 1

  for line in iter(output.splitlines()):
    x = re.match(r".*title.*: (.*)", line)
    print "x:"
    pprint.pprint(x)

    print "title:"
    pprint.pprint(title)

    if x == None:
      m1 = re.match(r".*Chapter #(\d+:\d+): start (\d+\.\d+), end (\d+\.\d+).*", line)
      title = None
    else:
      title = x.group(1)

    if m1 != None:
      chapter_match = m1

    print "chapter_match:"
    pprint.pprint(chapter_match)

    if title != None and chapter_match != None:
      m = chapter_match
      pprint.pprint(title)
    else:
      m = None

    if m != None:
      chapters.append({ "name": `num` + " - " + title, "start": m.group(2), "end": m.group(3)})
      num += 1

  return chapters

def getChapters():
  parser = OptionParser(usage="usage: %prog [options] filename", version="%prog 1.0")
  parser.add_option("-f", "--file",dest="infile", help="Input File", metavar="FILE")
  (options, args) = parser.parse_args()
  if not options.infile:
    parser.error('Filename required')
  chapters = parseChapters(options.infile)
  fbase, fext = os.path.splitext(options.infile)
  path, file = os.path.split(options.infile)
  newdir, fext = os.path.splitext( basename(options.infile) )

  os.mkdir(path + "/" + newdir)

  for chap in chapters:
    chap['name'] = chap['name'].replace('/',':')
    chap['name'] = chap['name'].replace("'","\'")
    print "start:" +  chap['start']
    chap['outfile'] = path + "/" + newdir + "/" + re.sub("[^-a-zA-Z0-9_.():' ]+", '', chap['name']) + fext
    chap['origfile'] = options.infile
    print chap['outfile']
  return chapters

def convertChapters(chapters):
  for chap in chapters:
    print "start:" +  chap['start']
    print chap
    command = [
        "ffmpeg", '-i', chap['origfile'],
        '-vcodec', 'copy',
        '-acodec', 'copy',
        '-ss', chap['start'],
        '-to', chap['end'],
        chap['outfile']]
    output = ""
    try:
      # ffmpeg requires an output file and so it errors
      # when it does not get one
      output = sp.check_output(command, stderr=sp.STDOUT, universal_newlines=True)
    except CalledProcessError, e:
      output = e.output
      raise RuntimeError("command '{}' return with error (code {}): {}".format(e.cmd, e.returncode, e.output))

if __name__ == '__main__':
  chapters = getChapters()
  convertChapters(chapters)

This took a good bit to figure out since I'm definitely NOT a Python guy. It's also inelegant as there were many hoops to jump through since it is processing the metadata line by line. (Ie, the title and chapter data are found in separate loops through the metadata output)

But it works and it should save you a lot of time. It did for me!

Covenanter

@JP. Glad to hear it! – Covenanter

This worked well once I ran ffmpeg -i independently, to determine the format of my file's metadata. I had to tinker with the regex since my chapters weren't of the format Chapter #dd:dd. It would be good to try and make your regex more robust :-) – Decrepit

Your way of determing the path only works for when using an absolute path for the input file. Otherwise the variable path is empty and therefore the path of the output files is a directory inside the document root, for example /test for the input file test.mp4. – Chigetai

thanks @clifgriffin, I liked your version and modified it to work in Python 3. I also cleaned up the imports and added leading zeroes to chapter number gist.github.com/showerbeer/97c1f31770572d05738cd2b74167f8a4 – Layman

I saved this as splitfilebychapter.sh. When I run from command line I issue splitfilebychapter.sh alargeaudiobook.mp3. It returns: splitfilebychapter.sh: error: Filename required. Is it looking for the name of an input file or output file? – Striation

Instead of posting the adjusted script, you may as well send a pull request since there is a link to the Github project. – Siphonophore

Answer 7

I was trying to split an .m4b audiobook myself the other day, and stumbled over this thread and others, but I couldn't find any examples using batch-script. I don't know python or bash, and I am no expert in batch at all, but I tried to read up on how one might do it, and came up with the following which seems to work.

This exports MP3-file numbered by chapter to the same path as the source file:

@echo off
setlocal enabledelayedexpansion
for /f "tokens=2,5,7,8 delims=," %%G in ('c:\ffmpeg\bin\ffprobe -i %1 -print_format csv -show_chapters -loglevel error  2^> nul') do (
   set padded=00%%G
   "c:\ffmpeg\bin\ffmpeg" -ss %%H -to %%I -i %1 -vn -c:a libmp3lame -b:a 32k -ac 1 -metadata title="%%J" -id3v2_version 3 -write_id3v1 1 -y "%~dpnx1-!padded:~-3!.mp3"
)

For your video file file, I have changed it to the following to handle both video and audio data by straight copying. I don't have a video-file with chapters, so I can't test it, but I hope it works.

@echo off
setlocal enabledelayedexpansion
for /f "tokens=2,5,7,8 delims=," %%G in ('c:\ffmpeg\bin\ffprobe -i %1 -print_format csv -show_chapters -loglevel error  2^> nul') do (
   set padded=00%%G
   "c:\ffmpeg\bin\ffmpeg" -ss %%H -to %%I -i %1 -c:v copy -c:a copy -metadata title="%%J" -y "%~dpnx1-!padded:~-3!.mkv"
)

Otero

This is broken. -ss and -to should be AFTER -i, and %%J shouldn't be enclosed in quotes because it already in quotes. also %%J contains a CR character (0x0D), which causes problems and needs to be stripped away. – Backbreaker

Also, because you are using -print_format csv, this breaks if the title contains new lines (and/or commas, possibly). – Backbreaker

@Backbreaker Not broken, just a bit dangerous. The order doesn't matter if there's a single -i. %%J does not automatically get quotes - what you refer to is probably that -print_format csv needs to emit quotes when the chapter title contains a comma. If so, cmd will cut off %%J at the embedded comma anyway, so there is no hope using cmd. If the chapter title just contains letters and spaces, "%%J" is the right way. However, you're right that it's easy to break with mysterious error messages and safer to omit token 8 and %%J altogether (just imagine a chapter title "& format c: &rem"). – Ambuscade

Answer 8

I wanted a few extra things like:

• extracting the cover
• using the chapter name as filename
• prefixing a counter to the filename with leading zeros, so alphabetical ordering will work correctly in every software
• making a playlist
• modifying the metadata to include the chapter name
• outputting all the files to a new directory based on metadata (year author - title)

Here's my script (I used the hint with ffprobe json output from Harry)

#!/bin/bash
input="input.aax"
EXT2="m4a"

json=$(ffprobe -activation_bytes secret -i "$input" -loglevel error -print_format json -show_format -show_chapters)
title=$(echo $json | jq -r ".format.tags.title")
count=$(echo $json | jq ".chapters | length")
target=$(echo $json | jq -r ".format.tags | .date + \" \" + .artist + \" - \" + .title")
mkdir "$target"

ffmpeg -activation_bytes secret -i $input -vframes 1 -f image2 "$target/cover.jpg"

echo "[playlist]
NumberOfEntries=$count" > "$target/0_Playlist.pls"

for i in $(seq -w 1 $count);
do
  j=$((10#$i))
  n=$(($j-1))
  start=$(echo $json | jq -r ".chapters[$n].start_time")
  end=$(echo $json | jq -r ".chapters[$n].end_time")
  name=$(echo $json | jq -r ".chapters[$n].tags.title")
  ffmpeg -activation_bytes secret -i $input -vn -acodec -map_chapters -1 copy -ss $start -to $end -metadata title="$title $name" "$target/$i $name.$EXT2"
  echo "File$j=$i $name.$EXT2" >> "$target/0_Playlist.pls"
done

Proctoscope

You don't need the j variable. You can loop from 0 to $((count-1)) and have n=$i because jq understands indexes prefixed with zeroes (example : jq -r ".chapeters[05]") – Gurolinick

It removes video it seems, hardocdes AAX secret and is a little broken here and there. But I liked playlist and filename/metadata stuff. So I posted a fixed-up version gist.github.com/akostadinov/… – Renunciation

Answer 9

in python

#!/usr/bin/env python3

import sys
import os
import subprocess
import shlex

def split_video(pathToInputVideo):
  command="ffprobe -v quiet -print_format csv -show_chapters "
  args=shlex.split(command)
  args.append(pathToInputVideo)
  output = subprocess.check_output(args, stderr=subprocess.STDOUT, universal_newlines=True)

  cpt=0
  for line in iter(output.splitlines()):
    dec=line.split(",")
    st_time=dec[4]
    end_time=dec[6]
    name=dec[7]

    command="ffmpeg -i _VIDEO_ -ss _START_ -to _STOP_ -vcodec copy -acodec copy"
    args=shlex.split(command)
    args[args.index("_VIDEO_")]=pathToInputVideo
    args[args.index("_START_")]=st_time
    args[args.index("_STOP_")]=end_time

    filename=os.path.basename(pathToInputVideo)
    words=filename.split(".");
    l=len(words)
    ext=words[l-1]

    cpt+=1
    filename=" ".join(words[0:l-1])+" - "+str(cpt)+" - "+name+"."+ext

    args.append(filename)
    subprocess.call(args)

for video in sys.argv[1:]:
  split_video(video)

Energetics

Thanks for this solution! I like it because it is cross-platform. It works for me on Windows, however, for non-ASCII characters support I had to add the character encoding explicitly: output = subprocess.check_output(args, stderr=subprocess.STDOUT, universal_newlines=True, encoding="UTF8") – Dunedin

Answer 10

Naive solution in NodeJS / JavaScript

const probe = function (fpath, debug) {
      var self = this;
      return new Promise((resolve, reject) => {
        var loglevel = debug ? 'debug' : 'error';
        const args = [
          '-v', 'quiet',
          '-loglevel', loglevel,
          '-print_format', 'json',
          '-show_chapters',
          '-show_format',
          '-show_streams',
          '-i', fpath
        ];
        const opts = {
          cwd: self._options.tempDir
        };
        const cb = (error, stdout) => {
          if (error)
            return reject(error);
          try {
            const outputObj = JSON.parse(stdout);
            return resolve(outputObj);
          } catch (ex) {
            self.logger.error("probe failed %s", ex);
            return reject(ex);
          }
        };
        console.log(args)
        cp.execFile('ffprobe', args, opts, cb)
          .on('error', reject);
      });
    }//probe

The json output raw object will contain a chapters array with the following structure:

{
    "chapters": [{
        "id": 0,
        "time_base": "1/1000",
        "start": 0,
        "start_time": "0.000000",
        "end": 145000,
        "end_time": "135.000000",
        "tags": {
            "title": "This is Chapter 1"
        }
    }]
}

Corydalis

Answer 11

Tweaked this answer to make output video names as '[count]-[chapter].xyz'

input="$1"
count=0
ffprobe \
    -print_format csv \
    -show_chapters \
    "$input" |
cut -d ',' -f '5,7,8' |
while IFS=, read start end chapter
do
    ffmpeg \
        -nostdin \
        -ss "$start" -to "$end" \
        -i "$input" \
        -c copy \
        -map 0 \
        -map_chapters -1 \
        "${count}-$chapter.${input##*.}"
    count=$((count+=1))
done

By

Answer 12

python3 json variant

#!/usr/bin/python3
import sys,os,subprocess,json

def get_chapters(inp):
    result=subprocess.run(["ffprobe", "-v", "16", "-show_chapters", "-of", "json", inp],
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT)
    # print(result.stdout.decode("utf-8"))
    chp=json.loads(result.stdout.decode("utf-8"))
    # print(json.dumps(chp,indent=2))
    if "chapters" in chp:
        if len(chp["chapters"])>0:
            print(inp)
            fno=os.path.splitext(os.path.basename(inp))[0]
            ext=os.path.splitext(inp)[1]
            for ch in chp["chapters"]:
                out=f'/tmp/{fno} - {ch["tags"]["title"]}{ext}'
                print(out)
                os.system(f'ffmpeg -ss {ch["start_time"]} -to {ch["end_time"]} -i "{inp}" -map 0 -c copy "{out}" -v 16')

if len(sys.argv)==1:
    path="."
    # path="./videos"
    for f in os.listdir(path):
        if os.path.splitext(f)[1].lower() in [".webm", ".mkv"]:
            get_chapters(os.path.join(path,f))
else:
    for i in range(1,len(sys.argv)):
        get_chapters(sys.argv[i])

Saluki