Add your MP4 file
Drop one or more .mp4 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.
MP4 to MTS
Pulling the soundtrack out of a .mp4 video into .mts 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 MP4 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 MP4 video to AVCHD video
Pulling the soundtrack out of a .mp4 video into .mts audio keeps what you can hear and drops the picture entirely. An .mp4 file is a multimedia container that bundles compressed video, audio, subtitles, and chapter data into a single stream-friendly package. It is the default delivery format for nearly every phone, camera, and video platform, which makes .mp4 the safest target when a clip has to play everywhere.
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. For this route the practical draw is the transport-stream base survives card errors and interrupted recordings well and h.264 essence is often modern enough to re-wrap without re-encoding — balanced against transport-stream packet overhead makes files larger than the same video in MP4, which is worth knowing before you commit a large batch.
Why convert MP4 to MTS?
The usual reason to take .mts audio out of a .mp4 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, fewer track, attachment, and chapter features than Matroska; on the target side, the payoff is the transport-stream base survives card errors and interrupted recordings well, which is exactly what you want for importing camcorder footage into Premiere, Resolve, or Final Cut.
MP4 vs MTS at a glance
| Aspect | MP4 video (.mp4) | AVCHD video (.mts) |
|---|---|---|
| Format type | Container — quality depends on the codecs and settings inside | Container — quality depends on the codecs and settings inside |
| How it stores data | typically carries H.264/AVC or H.265/HEVC video with AAC audio, though the box structure also accepts AV1, MP3, and timed-text tracks | uses 192-byte transport packets, standard 188-byte packets plus a 4-byte arrival timestamp, matching Blu-ray's BDAV layout |
| Strongest at | publishing video to the web, social media, or a client who has not specified a format | importing camcorder footage into Premiere, Resolve, or Final Cut |
| Weak spot | fewer track, attachment, and chapter features than Matroska | transport-stream packet overhead makes files larger than the same video in MP4 |
| Metadata | iTunes-style metadata atoms (title, artist, cover art) plus XMP and per-track language tags; ID3 is not native to the container | 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 |
Pick MTS as the output
Select .mts in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if MTS 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 MTS file. Outputs keep the original filename with the .mts extension.
MP4 to MTS questions, answered
Will converting MP4 to MTS lose quality?
Since mp4 is container-oriented and mts is container-oriented, the conversion preserves the source content exactly as stored; no additional compression pass is applied beyond what .mts itself requires.
Is it private to convert MP4 files here?
Yes — the .mp4 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 MTS file work?
Editing suites and VLC handle .mts directly, while browsers, phones, and many TVs fail to recognize the extension even though they could decode the H.264 inside. Re-wrapping to MP4 usually restores playback everywhere without touching quality.
Will the MTS file be bigger or smaller than my MP4?
Much smaller — the video stream is usually 80–95% of a .mp4 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 MP4 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, iTunes-style metadata atoms (title, artist, cover art) plus XMP and per-track language tags; ID3 is not native to the container; none of it is transmitted anywhere because the file never leaves your browser.
Can I convert MTS back to MP4?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .mp4 → .mts → .mp4 is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.