Convert MPEG-4 Audiobook (.m4b) to Apple Lossless Audio Codec (.alac) online for free. Fast, secure audio conversion with no watermarks or registration.
Upload your .m4b file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .m4a file when it's ready.
Converting M4B to ALAC (Apple Lossless) re-encodes the audiobook's AAC audio into Apple's lossless codec inside an M4A container. Since M4B audiobooks use lossy AAC at 32-64 kbps, the resulting ALAC file preserves the decoded signal losslessly but does not improve upon the original AAC quality. The chapter markers and bookmarking functionality of M4B are lost in the conversion to a standard ALAC M4A file.
Archival of decoded audiobook audio in a lossless format prevents any further generational quality loss if the file needs to be re-encoded in the future. If you plan to process, edit, or re-encode the audiobook audio multiple times, working from an ALAC intermediate avoids cascading lossy-to-lossy degradation. Some audio management systems also categorize ALAC files differently from M4B.
FFmpeg decodes the M4B's AAC audio to PCM and encodes using the ALAC codec into an M4A container. The resulting file is significantly larger than the M4B source because ALAC losslessly stores the decoded AAC signal (which includes all the PCM data needed to represent the decoded waveform). Chapter markers from M4B are discarded as M4A/ALAC does not natively preserve M4B chapter track data.
No quality improvement over the M4B source. The ALAC losslessly stores the decoded AAC signal, but that signal already contains the compression artifacts from the original AAC encoding. File size increases approximately 10-20x for typical 64 kbps audiobook sources.
| Device | M4B | ALAC |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Native |
| iPhone/iPad | Partial | Native |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Resolution: N/A
Bitrate: 256 kbps
AAC format required
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
M4B to ALAC is useful as an archival or intermediate step to prevent further generational loss. It does not improve audio quality but provides a lossless representation of the decoded audiobook.
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| No |
| Jellemzo | M4B | ALAC |
|---|---|---|
| Teljes nev | MPEG-4 Audiobook | Apple Lossless Audio Codec |
| Kiterjesztes | .m4b | .m4a |
| Leginkabb ajanlott | Chapter support | Lossless |