Extract Audio from MOV to M4B — Free Online Tool
Extract audio from a MOV file and save it as an M4B audiobook file, encoding the audio track to AAC at 128kbps while preserving chapter markers that MOV containers can carry. M4B's native support for bookmarking and chapter navigation makes it ideal for turning recorded lectures, interviews, or long-form video content into a listenable audiobook experience.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your MOV file here
or click to browse
Free — no uploads, no signups. Your files never leave your browser.
Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
MOV files typically store one or more audio tracks alongside video, often encoded in AAC — the same codec M4B uses natively. During this conversion, the video stream is completely discarded using the -vn flag, and the audio is encoded (or re-encoded) to AAC at 128kbps to ensure compatibility with the M4B container. Because both MOV and M4B use the MPEG-4 container family and share AAC as a common audio codec, the conversion is computationally lightweight. The -movflags +faststart flag restructures the output file so its metadata index sits at the front, which is especially useful if you plan to stream or progressively load the M4B. If your MOV source already contains chapter markers, those can be mapped through to the M4B output, preserving the navigational structure that makes M4B files useful for long-form listening.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, which is running here as FFmpeg.wasm compiled to WebAssembly and executing entirely inside your browser — no files leave your machine. |
-i input.mov
|
Specifies the input MOV file. FFmpeg reads the QuickTime container and identifies all available streams — video, audio, and any chapter or subtitle tracks — for processing. |
-vn
|
Disables video output entirely. Since M4B is an audio-only format, this flag tells FFmpeg to skip all video streams from the MOV source, which is what makes this an audio extraction rather than a full conversion. |
-c:a aac
|
Encodes the audio stream to AAC using FFmpeg's built-in AAC encoder. AAC is the required codec for M4B and is what enables compatibility with Apple Books, iPhone, iPad, and Apple CarPlay audiobook playback. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, a standard quality level for spoken-word audiobook content. Increase this to 192k or 256k if the source MOV contains music or high-fidelity narration that warrants better audio reproduction. |
-movflags +faststart
|
Relocates the MPEG-4 metadata (MOOV atom) to the beginning of the M4B file after encoding is complete. This is important if you plan to host the M4B on a podcast feed or audiobook server, as it allows playback to begin before the entire file has downloaded. |
output.m4b
|
Defines the output filename and extension. The .m4b extension signals to Apple Books, Overcast, and other audiobook-aware players that this file supports bookmarking and chapter navigation, distinguishing it from a generic .m4a music file with identical internal structure. |
Common Use Cases
- Convert a recorded university lecture or conference presentation saved as a MOV file into an M4B audiobook so students can listen on Apple Books or Overcast with chapter jump support
- Strip the audio from a professionally edited MOV interview or documentary and package it as an M4B podcast episode that supports bookmarking for listeners who pause mid-episode
- Turn a long-form MOV screen recording of a software tutorial into an M4B file so users can follow along audio-only on their phone while commuting
- Extract narration audio from a MOV-based e-learning course video and distribute it as an M4B audiobook compatible with iPhone, iPad, and Apple CarPlay without requiring video playback
- Convert a chaptered MOV video essay into an M4B so the chapter structure (e.g., introduction, argument, conclusion) is preserved and navigable in audiobook players
- Archive a recorded storytelling or audio drama produced in a video editing timeline (exported as MOV) into the M4B format designed specifically for long-form audio consumption and listener position bookmarking
Frequently Asked Questions
It depends on how the chapter data is stored in your specific MOV file. MOV supports chapter tracks as a dedicated reference track, and M4B natively supports MPEG-4 chapter metadata. FFmpeg can map MOV chapter markers to the M4B output in many cases, but the base command shown here does not explicitly include a -map_chapters flag, so results may vary by source file. If chapter preservation is critical, you can append -map_chapters 0 to the command to explicitly copy chapter metadata from the first input file.
With the command as shown, the audio is re-encoded to AAC at 128kbps even if the source is already AAC. This ensures the bitrate and profile are consistent with M4B expectations but does introduce a small generation of lossy re-encoding. If you want to avoid re-encoding and your source AAC is already at a compatible bitrate, you can replace -c:a aac with -c:a copy, though this only works reliably when the source audio codec and profile are already M4B-compatible.
The -b:a 128k flag controls the AAC audio bitrate. You can increase it to -b:a 192k or -b:a 256k for higher quality audio, which matters most if your source MOV contains music, rich narration, or high-fidelity recordings. For voice-only content like lectures or podcasts, 64k or 96k is often sufficient and produces much smaller M4B files. M4B files are typically meant for spoken-word content, so very high bitrates rarely offer a perceptible improvement for that use case.
M4B is structurally identical to M4A but is recognized by Apple Books, iPhone, and many podcast apps as a long-form audio format, which unlocks bookmarking (the app remembers exactly where you stopped listening) and chapter navigation. MP3 files do not natively support bookmarking in Apple's ecosystem, and M4A files are often treated as music rather than audiobooks, losing the bookmark feature. If your converted content is a lecture, story, or course you expect listeners to revisit across sessions, M4B is the correct format choice.
No — the -vn flag in the command instructs FFmpeg to completely ignore the video stream. The output M4B contains only the audio track, so file size is determined entirely by the audio duration and the 128kbps bitrate setting. A one-hour MOV video that is several gigabytes might produce an M4B of roughly 55–60MB at 128kbps, making M4B a very efficient format for distributing long-form audio extracted from large video files.
Yes. On macOS or Linux you can run a shell loop such as: for f in *.mov; do ffmpeg -i "$f" -vn -c:a aac -b:a 128k -movflags +faststart "${f%.mov}.m4b"; done. On Windows Command Prompt you would use a for loop with similar syntax. This is particularly useful if you have a series of recorded sessions or lecture parts you want to convert into individual M4B chapters or episodes in one pass.
Technical Notes
M4B uses the MPEG-4 Part 14 container, the same underlying structure as MP4 and M4A, with AAC as its standard audio codec. MOV is Apple's QuickTime container and shares significant structural overlap with MPEG-4, which is why FFmpeg handles this conversion efficiently — there is no complex container remapping required. The -movflags +faststart flag moves the MOOV atom to the beginning of the output file, which allows the M4B to begin streaming or loading before the full file is available, a useful property for podcast distribution servers. One notable limitation of M4B is that it does not support multiple audio tracks — if your MOV file contains alternate language tracks or a separate music/effects track, only the default (first) audio stream will be included in the output. M4B also does not support embedded subtitles, so any subtitle or closed-caption data in the MOV source is silently dropped. Metadata such as title, artist, and album tags from the MOV file may or may not transfer cleanly; for proper audiobook metadata (author, narrator, cover art), you may want to post-process the M4B with a dedicated tagging tool like Mp3tag or iTunes.