m4b-util 2025.4.16

m4b-util

A command line utility for creating, editing, and generally working with m4b files.

Sub-commands

This application is split into a number of subcommands which can be run from the main command. For a list of available commands, run m4b-util --help. For details on a specific sub-command, run m4b-util <command> --help.

Bind

The bind sub-command is designed to take a folder of audio files and convert them to a single m4b, treating each individual file as its own chapter. It can get chapter names from the original files' metadata, original files' names, from command line arguments, or just number them sequentially. By default, it only scans for mp3 files, but any file extension can be added via arguments.

Cover

The cover command adds and extracts cover images.

Example:

$ m4b-util cover /path/to/book.m4b --extract /path/to/old/cover.png --apply-cover /path/to/new/cover.png

Labels

The labels command converts between Audacity labels, FFMPEG metadata, and Audiobook chapter metadata. Label end times are ignored, as audiobooks need contiguous, non-overlapping chapters. When converting from a label file, the end time of each segment is set from the start time of the next segment.

Example:

$ m4b-util labels --from-label-file /path/to/labels.txt --to-book /path/to/existing/book.m4b --to-metadata-file /path/to/new_labels.txt

Example:

$ m4b-util bind /path/to/inputs  --title "My Book" --cover /path/to/cover.png -e m4a -e .mp4 --output-dir /path/to/output 

Slide

The slide command moves all chapters in a file by a specified duration, keeping the start and end times the same. It can optionally trim audio from the start of the file, shifting all chapters an equal amount.

Example:

$ m4b-util slide /path/to/input.mp3 --duration 5.1 --trim-start 2.5

Split

The split command takes a mode and a single audio file input, scans for silence or chapters (depending on mode), and writes out individual files containing the audio in-between.

Example:

$ m4b-util split silence /path/to/input.mp3 --output-dir /path/to/output --output_pattern "chapter_{:03d}.mp3"