Skip to content
Branch: master
Find file History
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.


This is a simple python script to convert m4b to mp3 and split them into seperate file for each chapter.




  1. Install python 2.7.xx (
  2. Download ffmpeg and place ffmpeg.exe in this directory or your PATH.
  3. Download libmp4v2.dll or compile your own dll, then place it in this directory.
  4. Download this script:
    • Download: m4b-converter
    • or Git: git clone

Ubuntu 10.10

  1. Install packages: sudo apt-get install python2.7 ffmpeg libavcodec-extra-52
  2. Download mp4v2 then compile and install.
  3. Download this script:
    • Download: m4b-converter
    • or Git: git clone

Ubuntu 12, 14, 16

  1. Install packages: sudo apt-get install python ffmpeg libavcodec-extra libmp4v2-2
  2. Download this script:
    • Download: m4b-converter
    • or Git: git clone

Debian 9.0 Stretch - 2017

  1. Install packages: sudo apt-get install python ffmpeg libavcodec-extra libmp4v2-2
  2. Download this script:
    • Download: m4b-converter
    • or Git: git clone


There are two ways to use this script:

  1. Drag your .m4b file(s) onto
  2. Using the command line which also offers more advanced options.

Command Line Help

usage: [-h] [-o DIR] [--custom-name "STR"] [--ffmpeg BIN]
			  [--encoder BIN] [--encode-opts "STR"] [--ext EXT] [--pipe-wav]
			  [--skip-encoding] [--no-mp4v2] [--debug] [--keep-tmp-files]
			  [--not-audiobook] [-b BITRATE] [-s SAMPLERATE]
			  filename [filename ...]

Split m4b audio book by chapters.

positional arguments:
  filename              m4b file(s) to be converted

optional arguments:
  -h, --help            show this help message and exit
  -o DIR, --output-dir DIR
						directory to store encoded files
  --custom-name "STR"   customize chapter filenames (see README)
  --ffmpeg BIN          path to ffmpeg binary
  --encoder BIN         path to encoder binary (default: ffmpeg)
  --encode-opts "STR"   custom encoding string (see README)
  --ext EXT             extension of encoded files
  --pipe-wav            pipe wav to encoder
  --skip-encoding       do not encode audio (keep as .mp4)
  --no-mp4v2            use ffmpeg to retrieve chapters (not recommended)
  --debug               output debug messages and save to log file, also keeps
						tmp files
  --keep-tmp-files      keep temporary files
  --not-audiobook       do not add genre=Audiobook
  -b BITRATE, --bitrate BITRATE
						bitrate for mp3 encoding, integer (example 64)
  -s SAMPLERATE, --samplerate SAMPLERATE
						sample Rate for mp3 encoding (example 22050
  --extract-cover-art   extracts cover art as cover.jpg

Chapter filenames

You can customize the chapter filenames with --custom-name "STR" where STR is a valid python format string.

Variable options
  • title - "chapter title"
  • num - "chapter number"
  • chapters_total - "number of chapters:
  • start - "chapters start time"
  • end - "chapters stop time"
  • durration - "chapters time durration"

Default: three digit chapter number, with leading zeros, and chapter title ("003 - My Title.mp3"):

--custom-name "%(num)03d - %(title)s"

Chapter title ("My Title.mp3"):

--custom-name "%(title)s"

Chapter number, without leading zeros, and chapter title ("3 - My Title.mp3"):

--custom-name "%(num)d - %(title)s"


By default the audio will be encoded with the lame mp3 codec using ffmpeg. The bit rate and sampling freq will be the same as the source file. If you wish to use other settings you can specify your own encoding options with --encode-opts "STR". STR will be passed to the encoder (--encoder or skip to use ffmpeg). Variables available:

%(outfile)s - output filename (required)
%(infile)s - .m4b file
%(bit_rate)d - bit rate of .m4b file
%(sample_rate)d - sampling rate of .m4b file


Convert multiple audio books (you can also drag multiple m4b files onto

python myfile.m4b otherfile.m4b

Include chapter number in the generated filenames: (example: "Chapter 10 - Some Title.mp3")

python --custom-name "Chapter %(num)d - %(title)s" myfile.m4b

If you rather want .mp4 files you can skip encoding to speed up the conversion process:

python --skip-encoding myfile.m4b

Force sampling freq to 22050 Hz and bit rate to 128 kbit/s:

python --bitrate 128 --samplerate 22050 myfile.m4b

Encode with lame.exe:

~~python --encoder lame.exe --pipe-wav --encode-opts "-V 3 -h - %(outfile)s" myfile.m4b~~


  • Does not add cover art to chapters other than 1
  • Cover art does not always extract, I've had some problems with m4b w/ png cover art
  • !!! Last chap gets cut off !!!!!!!!, i think i fixed it
  • output dir doesnt work with reletive dir

Change Log

  • 4/2017
    • Fix encoder error: Too many packets buffered for output stream 0:1.
    • Updated some installation instructions
    • Quiet output of ffmpeg durring encoding, (except in debug)
    • Improved filenaming, '%(num)03d - %(title)s', with some inteligence
    • Added ID3 track numbers
    • Added ID3 genre=Audiobook (by default)
    • Delete temp files/folder (by default)
    • Automaticly changes bitrate 63kbps(M4B) to 64kbps(MP3), increase compatablity
  • 5/2017
    • Fixed problem with encoding file with single chapter
    • Extracts cover art, as command line option (works most of the time)
    • Added bitrate and sample rate command line options
    • bug fixes
  • 6/2017
    • --Remove/ignore chapters of zero durration (
    • Non standard bitrates changes to 32, 48, 96, 128, 160kbps
  • 7/2017
    • Fixed broken command line opts
    • Fixed no id3 on non-mp3
    • Fixed opts --ext, -skip-encoding,
    • Added exit on file not found
    • Display ffmpeg output in debug mode
    • Fix exit on ffmpeg fail
    • added file not found error


  • Cover art is missing on tracks!=1
  • Check compatability for windows, etc
  • Change default output dir to be current working directory (maybe)
    • C:\Users%USERPROFILE%\My Music\
    • $HOME/Documents/
  • Fix extract_cover_art, does not work all the time
  • Retest all command line options
    • OK: --help
    • Ok: --bitrate
    • Ok: --samplerate
    • Ok (most of the time): --extract-cover-art
    • Ok: --debug
    • ?: --output-dir
    • Failed: --custom-name
    • Ok: --ffmpeg
    • : --encoder
    • : --encode-opts
    • Ok: --ext
    • : --pipe-wav
    • Ok: --skip-encoding
    • OK: --keep-tmp-files
    • Ok: --not-audiobook
    • Failed: --no-mp4v2 doesn't work
  • Add custom name validity check
  • Fix: no-libm4b option
  • Add useful error output on
  • Fix: print ffmpeg output on fail while not in debug
You can’t perform that action at this time.