How to convert M4B to AAC
- Add your .M4B file - drop it in the box above or click to browse.
- Convert it to .AAC in a few seconds.
- Download your new .AAC file.
What to expect
- Stream-copy extraction (
-c:a copy) is lossless - the AAC bytes are moved out of the container without decoding, so quality is identical to the source. - Chapter markers, bookmarks, and cover art live in the MP4 container and will not appear in the output
.aacfile. - DRM-protected audiobooks from the iTunes Store cannot be converted - only DRM-free
.m4bfiles work with standard converters.
Frequently asked questions
Does converting M4B to AAC reduce quality?
No, provided the tool uses stream copy. The AAC data is extracted without decoding or re-encoding, so quality is bit-for-bit identical to the source.
Will chapters carry over to the .aac file?
No - chapter data lives in the MP4 container, not the audio stream. To keep chapters, remux to
.m4a with ffmpeg -i book.m4b -c copy book.m4a instead.Can I convert a DRM-protected M4B audiobook?
No. FairPlay DRM locks the audio to Apple-authorised devices, and standard converters including FFmpeg cannot extract the audio from a protected file.
Why not just rename .m4b to .m4a instead of converting?
Renaming keeps the MP4 container intact with all chapters, metadata, and cover art and plays in any AAC-capable app. Converting to raw
.aac is only needed when a specific tool requires a bare bitstream.
