MP4 to M4B Converter
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Supports: MP4, M4V
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Pull the audio out of an MP4 video and save it as M4B — the MPEG-4 audiobook container. The output is AAC audio in an MPEG-4 file, but the .m4b extension is what makes the difference: audiobook apps like Apple Books treat .m4b files as audiobooks and remember your playback position, so you resume exactly where you left off instead of restarting from the beginning. There is no video in the result — this is an audio-only extraction.
How to Convert MP4 to M4B
- Upload Your MP4 File: Drag and drop your
.mp4(or.m4v) file, or click "Add Files" to browse. You can queue several videos and convert them with the same settings. - Pick a Quality Preset: Open Advanced Options and choose a Quality Preset (it defaults to Highest; "Very High (Recommended)" is a good balance for spoken word). The output codec is AAC, the standard codec for M4B.
- Set Bitrate or Trim (Optional): Use Custom Bitrate or Constant Bitrate to control file size, switch Audio Channel to Mono to shrink a voice recording, or use Trim to keep only part of the timeline.
- Convert and Download: Click Convert and download your M4B. No sign-up, no watermark.
M4B vs M4A vs MP3 for Audiobooks
| Property | M4B | M4A | MP3 |
|---|---|---|---|
| Container / codec | MPEG-4, AAC | MPEG-4, AAC | MPEG-1 Layer III |
| Resume-playback in audiobook apps | Yes (extension signals "audiobook") | No (treated as music) | No |
| Carries chapter-marker metadata | Yes, if present in the file | Yes, if present | Not natively |
| Quality at the same bitrate | Generally better than MP3 | Same as M4B | Baseline |
| Can hold FairPlay DRM | Yes (Audible/Apple Store files) | Rarely | No |
| Best for | Long spoken-word audio you stop and resume | Music and general audio | Maximum device compatibility |
M4B and M4A are technically the same MPEG-4 + AAC container; the .m4b extension is the signal that tells players to behave like an audiobook player. If you want music behavior instead, convert to M4A. If you need the widest possible device support, MP3 plays almost everywhere.
Frequently Asked Questions
Will the M4B remember my place like a real audiobook?
Yes, in apps that honor the audiobook extension. Apple Books and most dedicated audiobook apps recognize a .m4b file as an audiobook and automatically save your playback position, so reopening the app resumes where you stopped. With .m4a or .mp3, most apps restart from the beginning. The position memory is created by the player keying off the .m4b extension, not embedded in the file by the converter.
Does this add chapter markers to the audiobook?
No. Chapter markers are separate metadata, and this converter extracts and re-encodes the audio without generating them. If your source MP4 already contains chapter data it can carry through, but a plain video has none — to author named chapters from scratch you need a dedicated audiobook-chapter tool. Resume-playback still works without chapters, because that comes from the .m4b extension.
Why convert to M4B instead of just keeping the MP4?
An MP4 carries the full video stream, so it is far larger than the audio alone and most audiobook apps will not import a video file as a book. Extracting to M4B drops the video track entirely, leaving a compact AAC audio file that audiobook players accept and resume. It is the right move for recorded lectures, talks, or narrated videos you want to listen to like an audiobook.
Can it convert a DRM-protected audiobook video?
No. Files protected with Apple's FairPlay DRM (for example, purchases from the Apple Books or Audible stores) are encrypted and cannot be re-encoded here. Many M4B files from indie publishers and personal recordings are DRM-free and convert without issue, but protected content is blocked by design.
What does this converter actually output?
In our testing, an MP4 with an AAC soundtrack produces an M4B that is AAC audio inside an MPEG-4 container with the .m4b extension — the format Apple Books treats as a resumable audiobook. The audio is re-encoded, so picking a high Quality Preset or a bitrate at or above the source keeps the difference inaudible for speech. It does not inject chapter markers or cover art that were not already present. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — no sign-up, no watermark, never shared or made public.