Audiobook Splitter

What it's for

Break an audiobook into one file a chapter. Some players, car stereos and older devices don’t play M4B or don’t show its chapters, and it’s easier to share or edit one chapter than a whole book.

For example, when your car only plays a folder of numbered tracks, split the book here and copy the chapters to a USB stick.

How to use it

Choose an .m4b (or an .m4a or .mp4 with chapters), or drop it on the page. The chapters are listed with where each starts. They’re read from Apple’s chapter track, or from Nero’s chapter list when there’s no track.

Save the chapters (ZIP) saves <book>-chapters.zip with one numbered file a chapter. M4A (remembered in this browser) copies the sound exactly as it is, which is quick and loses nothing; each file keeps the book’s tags and cover, with the chapter’s title as its title, the book’s title as the album, and its number as the track. MP3 decodes and re-encodes each chapter at 96 kbit/s, for players that only take MP3.

Example

Make Tones.m4b as in the Audiobook Maker’s example, and open it here.

It lists 0:00 · tone-440hz and 0:03 · tone-660hz, and saves Tones-chapters.zip holding 01 tone-440hz.m4a and 02 tone-660hz.m4a.

Good to know

A chapter is cut at the block of sound (a few hundredths of a second) where it starts, so it may begin a moment early or late. The MP3s are named by chapter but carry no tags, and re-encoding loses a little quality. Books with DRM (copy protection), such as Audible’s .aax files, can’t be split. Fragmented MP4 files aren’t read. The whole book is held in memory, so a very large one may be too much for a phone.