How To Make M4B Files

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What are M4B files?

An M4B file is an audio file which can be bookmarked. This is the audio-book file type. These files can have chapter markers which can be skipped through as you would skip through files on a play list. They can have built in cover art and chapter images. They will remember where you left off each time you stop the file and come back to it . And variable speed settings on Ipods and a growing number of other mp3 players can be utilized by this file type. The ability to bookmark allows for as little as one large file instead of many small ones without the burden of fast forwarding to find your spot every time you resume listening or the fear of otherwise losing your place. The reduced number of files also makes browsing through your files to find your book and your place in it much less effort.

How to make M4B files.

There are a few different programs which can do this. The easiest to use and best is Chapter and Verse.

The LibriVox mp3 files you start out with might be bigger than you want. You can use a file converter such as Super to reduce the file size of the mp3s you are working with or change the quality settings in Chapter and Verse before converting them into M4B.

Because you will end up with one large file (or just a few depending on how long the total run time of your book is) certain things will become redundant and unnecessary. Such things as introductions at the beginning of every chapter beyond the first (of course reader's names should be kept if given) or announcements of the end of a chapter which would then be followed directly by an announcement of the beginning of a new chapter can be removed with an editor such as Audacity if you so choose.

When adding chapter images you may encounter errors with M4B files that contain chapter images larger than 300 pixels in either direction. To avoid this or if your file does not play after you build it you can resize the images in an editor (such as Gimp). Cover images appear to have no such problem as Chapter and Verse automatically resizes the cover image used.

An editor (such as Gimp) may be used to make cover images (of course be sure the image you work with is in the public domain). If you have little experience editing images this can be as simple as cropping an appropriate image into a square or near square and adding the title of the book and the author's name somewhere over the top. Often a book will have CD cover art created for it; this works perfectly for an audio book file cover.

To share your completed M4B file(s); create an account at, click on the "Upload" button in the top right hand corner of the web page and then the "share" button which appears in the same location, select your file, fill in the information about your file(s) as it uploads (title, description, author, etc), mark it as an audio file after it has been uploaded and you are asked if it belongs in the "other" category to which it is automatically assigned and mark it as public domain. After you have done the above and clicked "Share My File(s)" you well be given the address of your new page. Near the top of this page is an "Edit Item" link which you can use to make changes and at the bottom of the "change the information" page, to which you will be directed from the "Edit Item" page, is an option to prevent derivations of your file (which would be useless and a waste of space as they will be larger than your new file and redundant with the existing LibriVox mp3s also on the archive).

More information

Existing LibriVox books converted into M4B files can be found here.

If you are interested in converting LibriVox books to M4B audio book files or have done so already please let it be known here when you have. Just posting a message containing a link to the LibriVox catalog page for that particular book and a link to your file with the file name as the title of the book (without words like "A" or "The" at the beginning) followed by the bit-rate of the file (as an example something like DivineComedy_32kb.m4b). You can upload the file for us somewhere such as or at as a test file. We will then add the file to our collection and make it available.