MTS to M4B Converter
Processing entirely on your device — large files may take a moment.
MTS is the raw AVCHD clip format Sony/Canon camcorders write — high-bitrate H.264 transport streams straight off the memory card. Converting M4B to MP3 frees audiobooks to play on car stereos, dumb players and anything without chapter support.
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 MTS compares to M4B
| MTS | M4B | |
|---|---|---|
| Compatibility | ffmpeg, VLC, Premiere | Apple Books, Audible |
| Best for | Camcorder footage ingestion | Chaptered audiobooks |
How to convert MTS to M4B
- 1
Select your files
Select your MTS video.
- 2
Convert instantly
The engine demuxes the container and encodes the audio track into your chosen format.
- 3
Download results
Download the M4B audio — the video track is simply dropped.
About the MTS format
MTS is what actually comes off a Sony or Canon AVCHD camcorder's memory card: high-bitrate H.264 transport streams with AC-3/PCM audio, often split across a BDMV folder structure. The video inside is excellent — the container is what edit software refuses to import.
Converting MTS to MP4 remuxes or re-encodes into a container every device opens. Stream-copy is possible when the H.264 profile is baseline-compatible; otherwise a light re-encode fixes compatibility without visible loss.
+ Strengths
- ✓Native camcorder quality (24-28 Mbps)
- ✓Audio in AC-3/PCM survives remux
- ✓ffmpeg handles the transport stream natively
! Limitations
- −AVCHD H.264 profiles not always stream-copyable
- −Interlaced variants need deinterlacing
- −60p modes confuse older editors
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
Why convert MTS to M4B?
Converting makes sense where the strengths of M4B meet what MTS cannot give you. Chapter markers survive on Apple platforms Meanwhile AVCHD H.264 profiles not always stream-copyable One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this MTS to M4B 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 MTS to M4B?
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.
Will the audio track be kept?
Yes. The audio is carried over and re-encoded to the standard audio codec of M4B, staying in sync with the video. If your MTS file has multiple audio tracks, the first one is used.
Does converting MTS to M4B re-encode my video?
Yes. The video is decoded and re-encoded with the settings chosen by the quality slider, which is what allows the format and size to change. For an archival copy, keep higher quality; for sharing, lower quality gives a much smaller file.