Voxbound / M4B chapters not showing

M4B chapters not showing in Apple Books or Audiobookshelf? Why, and how to fix it

An audiobook that plays as one long track, skips a chapter, or shows chapters on one device but not another can have several causes. This page covers the common ones: how to spot each, and how to fix it.

Updated 24 September 2026. Every FFmpeg behaviour on this page was reproduced with FFmpeg 8.1. Claims about how Apple's apps and Audiobookshelf behave link to their sources, and suggestions are marked as such.

First, check what's in the file

Start by finding out whether the file has chapters at all. In PowerShell, with FFmpeg installed, run:

ffprobe -v error -show_chapters -of compact "book.m4b"

Each chapter prints as one line with its start time, end time and title. In Voxbound, the Repair & verify tab gives the same count: click Choose file under Verify a file, pick a profile and click Run verification.

No lines means the file has no chapters, which is the first cause below. If chapters are listed but a player still doesn't show them properly, don't assume the file is fine: this check doesn't show which of the two chapter formats holds them or whether they're in order. Work through the two formats, out-of-order chapters and more than 255 chapters before blaming the player.

The file was joined without its chapters

The book plays as one long track in every player.

Joining audio files doesn't carry their chapters over by itself. In testing, joining M4B files with FFmpeg's concat demuxer and -c copy kept no chapters at all, and FFmpeg's concat filter kept only those of the first file that had any, which is FFmpeg's documented default for -map_chapters.

To fix it, make the file again with a chapter list. Our guide to merging MP3 files into an M4B shows both ways: Voxbound, which makes one chapter per source file that you can rename, and the manual way with FFmpeg and a chapter file.

It's named .m4a, not .m4b

Apple's apps treat the book as an ordinary audio file rather than an audiobook with chapters.

An M4A and an M4B are the same kind of file, but Glenn Fleishman, writing in Six Colors, found when loading his own audiobook into Books that the .m4a version was treated as plain audio and the .m4b version as an audiobook with chapters.

To fix it, rename the file so it ends in .m4b, then import it again. In Books on a Mac, choose File, then Import, as Apple's guide to adding audiobooks explains.

The chapters are only in one of the two formats

Chapters show in some apps but not in others.

An M4B can store chapters in two ways: a QuickTime chapter track and a Nero chapter list. A file made by an older or simpler tool may have only one of them, and a player that reads the other one then finds no chapters. Current FFmpeg writes both. FFmpeg reads the QuickTime track when it's there, and so does Audiobookshelf, which gets its chapters through FFmpeg.

To fix it, copy the file through FFmpeg once. This doesn't re-encode the audio, keeps the title, author and cover, and writes the chapters in both formats:

ffmpeg -i "book.m4b" -map 0:a -map 0:v? -c copy -disposition:v attached_pic -movflags +faststart "book-fixed.m4b"

Then import book-fixed.m4b instead.

The chapters are out of order or overlap

A chapter is missing, shows as zero length, or starts at the wrong time.

If a chapter's start time comes before the one listed above it, the QuickTime chapter track breaks. In testing, a chapter at 20 seconds listed first turned into an empty entry at the very start, and the real chapter disappeared; listed in other wrong orders, chapters landed at the wrong times. Any player that reads the QuickTime track shows this, including Audiobookshelf, which gets its chapters through FFmpeg. Overlapping chapters are silently cut short, and a chapter with no length is written without any warning.

To fix it, put the chapter list in time order, make each chapter end where the next begins, and remove empty ones, then make the file again. Voxbound's Chapters tab flags each of these problems and has an Auto-fix button that does all three, and clicking Merge files warns you and offers to fix the list first.

There are more than 255 chapters

In some players, chapters stop partway through a long book.

The Nero chapter list holds at most 255 chapters, so a player that reads only that list can show no more than 255. The QuickTime chapter track holds them all: a 300-chapter test file had all 300 there and only the first 255 in the Nero list.

To fix it, merge short chapters so the book has 255 or fewer, or use a player that reads the QuickTime chapter track.

Audiobookshelf still shows the old chapters

You fixed the file, but Audiobookshelf shows the same chapters as before.

By default, Audiobookshelf's own metadata file takes priority over the tags inside the audio file (see Audiobookshelf's book metadata documentation), and its scanner uses the chapters saved there when there are any. It also only reads an audio file again when it sees that the file has changed.

To fix it, correct the chapters in the book's chapter editor in Audiobookshelf, or change the library's metadata order so the audio file's tags come first, as the documentation suggests, and scan again. If that doesn't take, remove the book from the library and add it back.

Audiobookshelf shows one chapter per file

A book made of many files shows one chapter per file, or repeats chapters.

When a book is a folder of several files, Audiobookshelf builds the chapter list from the files: one chapter per file, unless the first file has chapters of its own, in which case it uses the chapters inside the files.

To fix it, merge the files into one M4B with the chapters you want, then add that single file to the library in place of the folder.

Chapters show on the Mac but not the iPhone or iPad

The chapter list is right in Books on the Mac but wrong or missing on a synced device.

Audiobooks you add yourself reach an iPhone or iPad through a Finder sync from the Mac, not through iCloud, as Six Colors describes. If the device keeps showing the old chapters, our suggestion is to remove the book from the device, import the fixed file into Books on the Mac, and sync again.

Making files that don't have these problems

Most of the causes above come from how the file was made. Voxbound is built to avoid them, for a one-off €9.99:

• it saves M4B files with the .m4b extension and writes the chapters in both the QuickTime and Nero formats;
• it flags chapters that are empty, out of order or overlapping, Auto-fix repairs the list in one click, and clicking Merge files warns you before writing a list with problems;
• chapter lists you import are trimmed to the real length of the audio, and empty chapters are dropped;
• with the Apple Books, Audiobookshelf or Prologue profile, every export is checked for chapters, along with its codec, sample rate and title.