M4B to W64 Converter
Processing entirely on your device — large files may take a moment.
MPEG-4 Audiobook and Sony Wave64 exist for different jobs: M4B is the audiobook flavour of M4A — AAC audio with chapter markers, used by Audible and Apple Books. Convert W64 recordings to WAV or FLAC for standard editors.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How M4B compares to W64
| M4B | W64 | |
|---|---|---|
| Compatibility | Apple Books, Audible | Sony Vegas, ffmpeg, Sound Forge |
| Best for | Chaptered audiobooks | Long-duration uncompressed sessions |
How to convert M4B to W64
- 1
Select your files
Drag & drop your M4B files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to W64". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted W64 file individually, or grab everything at once as a ZIP archive.
About the M4B format
M4B is M4A wearing an audiobook badge: the same AAC audio in an MP4 container, plus chapter markers that Apple Books and Audible apps render as a scrubbing timeline. Buy an audiobook outside Audible and it likely arrives as M4B.
The format is deliberately chained to Apple's book ecosystem. Converting M4B to MP3 sets the book free: car stereos, gym players, old iPods and every app without chapter support will play it — though the chapter marks themselves are flattened away.
+ Strengths
- ✓Chapter markers survive on Apple platforms
- ✓Efficient AAC audio
! Limitations
- −Chapters vanish in MP3 conversion
- −Non-Apple support is patchy
About the W64 format
W64 is Sony's Wave64 — what happens when WAV's 32-bit size fields run out of road. A RIFF variant with 64-bit offsets, it shrugs off the 4 GB ceiling that makes plain WAV choke, which is why long field-recording sessions and Sony Vegas projects land in W64.
Inside, it is the same uncompressed PCM as WAV — ffmpeg hands W64 to WAV, FLAC or MP3 without touching a single sample, so conversion is purely about container compatibility.
+ Strengths
- ✓No 4 GB size ceiling — hours-long recordings
- ✓Bit-exact PCM, same as WAV inside
- ✓Standard in Sony Vegas workflows
! Limitations
- −Almost nothing outside Sony tools opens it
- −Uncompressed — very large files
- −Legacy niche — new tools prefer RF64
Why convert M4B to W64?
There is a concrete reason this conversion exists: Chapters vanish in MP3 conversion W64 sidesteps that — No 4 GB size ceiling — hours-long recordings If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this M4B to W64 converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for M4B to W64?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.
Will converting M4B to W64 reduce audio quality?
If W64 is lossless, the output contains everything the M4B file contains — no further loss is added. If W64 is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.