File Convert

Convert M4B to AU

Free online M4B-to-AU converter — upload a M4B file and download a AU. Fast, private, no signup.

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M4B vs AU

M4B

MPEG-4 audiobook (AAC, with chapter support).

About M4B ↗

AU

Sun/NeXT AU — a simple, long-lived PCM audio container.

About AU ↗

M4B to AU: frequently asked questions

How do I convert M4B to AU?

Drop your M4B file into the converter above — we auto-detect the real format from its bytes, convert it, and give you a AU to download. No software to install.

Is the M4B to AU converter free?

Yes. Convert M4B to AU for free right in your browser, with no account needed to get started.

Is it safe and private?

Your file is transferred over an encrypted connection and anonymous uploads are temporary. You can also view and strip metadata (location, device, author) before you download.

What's the difference between M4B and AU?

MPEG-4 audiobook (AAC, with chapter support). Sun/NeXT AU — a simple, long-lived PCM audio container.

Related conversions

Convert M4B to: MP3 · WAV · FLAC · M4A · AAC · AC3 · AIFF · CAF · DTS · M4R

Convert to AU from: AAC · AC3 · AIFF · AMR · APE · CAF · DFF · DSF · DTS · FLAC

Browse all supported formats →