What is a .M4B file?
M4B is an MP4-based audiobook format that supports chapters and bookmarks. Used by Apple Books and audiobook players.
- Did you know
- M4B adds chapter and bookmark support on top of the M4A audio format.
- M4B is the same MPEG-4 audio container as M4A, with a separate extension chosen to flag audiobooks.
- Apple Books and iTunes remember your place in an M4B file, resuming exactly where you stopped.
- It supports chapter markers, letting players jump between sections of a long recording.
- Beneath the audiobook labelling it typically carries ordinary AAC-encoded audio.
- What Analyser shows you
- Inspect the waveform, spectrogram, codec, bitrate, channels, and tags of MP3, WAV, FLAC, M4A, AAC, OGG, and Opus audio.
- Open a .M4B file
- Drag a .M4B file onto the Analyser home page (or tap to pick one). It opens entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.