MP3 to Audiobook iTunes
As you know, MP3 files will be imported in the Music section by default. Actually, you're able to move the MP3 list to Audiobook section in iTunes without converting MP3 to M4B.
Step 1. Launch iTunes, go to File menu > Add File/Folder to Library to import your MP3 files. Alternatively, just drag and drop them into iTunes.
Step 2. Select all imported MP3 files via holding down the Ctrl key for multiple selection. Right click the mouse and choose "Get Info", click "Edit Items" on the prompted dialog box.
Step 3. On the popup window, go to the Options tab, switch media kind from Music to Audiobook and click OK. Then the MP3 list will be moved to the Audiobook section of iTunes. They'll show up as audiobooks now.
Note: In fact, this method saves yourself the trouble of converting them to M4B format, but doesn't change the MP3 files themselves. To create an M4B audiobook that supports chapters and bookmarking from a list of MP3 files, just keep reading.
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