Free online ALAC to M4B converter

Source format: ALAC

ALAC stands for Apple Lossless Audio Codec. It is a lossless audio format used to store music without quality loss compared with the original recording. ALAC is commonly used by Apple devices and software, including iTunes, Music, iPhone, iPad, and macOS media libraries. Typical use cases include archiving CD-quality audio, keeping a high-quality music collection, and syncing lossless tracks across Apple ecosystems.

Target format: M4B

M4B is an MPEG-4 audiobook container format, closely related to M4A. It is widely used for audiobooks and spoken-word content because it can support chapter markers, metadata, and resume playback in compatible players. The main advantage of M4B is convenience for long-form audio: listeners can stop and continue from the same point, and chapters make navigation easier.

How to convert ALAC to M4B

The conversion is usually straightforward because both formats are based on the MPEG-4 family. In many cases, you can simply change the container while keeping the audio stream intact, which preserves quality and is much faster than re-encoding.

1. Check the source file. Make sure the ALAC file contains spoken audio or an audiobook-style recording. If it is music, M4B will still work technically, but it is less common than M4A.
2. Choose a desktop tool. Good options include FFmpeg, ffmpegX, Audacity for editing before export, or iTunes/Music for library-based audiobook workflows. For a simple conversion, FFmpeg is the most reliable choice.
3. Convert with FFmpeg. If the ALAC audio is already inside an MP4/M4A-style container, you can often remux it to M4B without re-encoding using ffmpeg -i input.m4a -c copy output.m4b. If your source is a standalone ALAC file or a different container, FFmpeg can still create an M4B file by copying the audio stream when compatible.
4. Add chapters and metadata if needed. For audiobooks, chapter markers and tags are important. FFmpeg can embed metadata from a chapter file or from command-line tags, and dedicated audiobook tools can help prepare chapterized output.
5. Verify the result. Open the M4B file in a compatible player such as Apple Books, iTunes/Music, or another audiobook-capable app to confirm playback, metadata, and chapter navigation.

If you prefer a browser-based workflow, you can convert the file on 101convert.com for free without installing any software.

Quality, compatibility, and limitations

ALAC is lossless, so if you use stream copy or remuxing, the audio quality remains unchanged. However, M4B support varies by player: some apps treat it like M4A, while audiobook players recognize chapters and resume position more reliably. If your goal is a true audiobook experience, make sure the file includes proper metadata and, ideally, chapter markers. Also note that some devices may not display M4B files correctly if the extension or tags are missing, even when the audio itself is valid.