Add your MTS file
Drop one or more .mts files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
MTS to M4V
Pulling the soundtrack out of a .mts video into .m4v audio keeps what you can hear and drops the picture entirely. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop MTS files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting AVCHD video to MPEG-4 video
Pulling the soundtrack out of a .mts video into .m4v audio keeps what you can hear and drops the picture entirely. An .mts file is AVCHD footage as written to a camcorder's memory card, containing H.264 video inside an MPEG transport stream. Sony and Panasonic camcorders from the late 2000s onward filled SD cards with .mts clips, so the extension is familiar to anyone importing family or event video.
An .m4v file is Apple's flavor of the MPEG-4 container, used by iTunes for movies, TV episodes, and music videos. Structurally it is almost identical to .mp4, but the .m4v extension signaled iTunes-specific features such as chapter markers and, on purchased content, FairPlay copy protection. For this route the practical draw is a DRM-free .m4v is a plain MP4, so a rename alone often fixes compatibility and carries chapters and artwork more gracefully than most containers — balanced against fairPlay-protected files play only in Apple apps on authorized devices, and no converter can open them, which is worth knowing before you commit a large batch.
Why convert MTS to M4V?
The usual reason to take .m4v audio out of a .mts file is that only the sound matters — a talk, interview, song, or podcast segment. Keeping the video stream would waste storage, and a dedicated audio file is easier to trim, tag, and play. On the source side, transport-stream packet overhead makes files larger than the same video in MP4; on the target side, the payoff is a DRM-free .m4v is a plain MP4, so a rename alone often fixes compatibility, which is exactly what you want for playing back iTunes-era video libraries.
MTS vs M4V at a glance
| Aspect | AVCHD video (.mts) | MPEG-4 video (.m4v) |
|---|---|---|
| Format type | Container — quality depends on the codecs and settings inside | Container — quality depends on the codecs and settings inside |
| How it stores data | uses 192-byte transport packets, standard 188-byte packets plus a 4-byte arrival timestamp, matching Blu-ray's BDAV layout | identical ISO base media layout to MP4, distinguished only by branding atoms and the extension |
| Strongest at | importing camcorder footage into Premiere, Resolve, or Final Cut | playing back iTunes-era video libraries |
| Weak spot | transport-stream packet overhead makes files larger than the same video in MP4 | fairPlay-protected files play only in Apple apps on authorized devices, and no converter can open them |
| Metadata | recording date, camera settings, and GPS coordinates on some models are stored in the AVCHD folder's clip-info files rather than in the .mts stream itself | full iTunes atom metadata: title, show, season, episode, artwork, chapters, and content ratings |
Pick M4V as the output
Select .m4v in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if M4V is selectable, the route is real and validated.
Convert on your device
Press Convert. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid M4V file. Outputs keep the original filename with the .m4v extension.
MTS to M4V questions, answered
Will converting MTS to M4V lose quality?
Since mts is container-oriented and m4v is container-oriented, the conversion preserves the source content exactly as stored; no additional compression pass is applied beyond what .m4v itself requires.
Is it private to convert MTS files here?
Yes — the .mts file is processed inside your browser tab and never uploaded. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded. Close the tab and the file is gone from memory.
Where will the M4V file work?
Apple devices treat .m4v as native, and most other players accept the file after inspecting its contents or following a rename to .mp4. The exception is DRM-protected iTunes video, which remains locked to Apple's own apps.
Will the M4V file be bigger or smaller than my MTS?
Much smaller — the video stream is usually 80–95% of a .mts file's weight, and it is discarded entirely. The remaining audio is re-encoded at the bitrate implied by your quality setting.
What happens to the metadata in my MTS file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, recording date, camera settings, and GPS coordinates on some models are stored in the AVCHD folder's clip-info files rather than in the .mts stream itself; none of it is transmitted anywhere because the file never leaves your browser.
Can I convert M4V back to MTS?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .mts → .m4v → .mts is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.