MTS to MP4 Converter
FileFlip converts MTS to MP4 entirely inside your browser, using WebCodecs and FFmpeg compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an MTS file to MP4?#
- Drop your MTS file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to MP4 and the conversion starts on its own. FileFlip usually downloads nothing, falling back to 30.8 MB of WebAssembly if your browser cannot encode these codecs itself, then runs WebCodecs and FFmpeg on your own machine.
- Save the MP4 file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting MTS to MP4 lose quality?#
Sometimes. When the codecs inside the MTS file are ones the MP4 container can hold, the streams are copied straight across and nothing at all is lost. When they are not, the file has to be decoded and encoded again, and that step does cost a little quality.
Is it safe to convert MTS files online?#
Yes, because nothing is uploaded. FileFlip converts MTS files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What MTS to MP4 actually does to the file#
Converting MTS to MP4 runs on WebCodecs and FFmpeg, usually downloads nothing, falling back to 30.8 MB of WebAssembly if your browser cannot encode these codecs itself, copies the streams through when the codecs fit and re-encodes when they do not.
| Engine | WebCodecs and FFmpeg |
|---|---|
| Conversion path | One step: MTS → MP4 |
| Downloaded to your browser | Nothing in most browsers, or 30.8 MB if yours cannot encode these codecs itself |
| Quality | Lossless when the codecs fit, lossy when they do not |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Encoded streams | Sometimes | Survives for some files and not others. |
Worth knowing before you start:
- the FFmpeg fallback is an LGPL build, so a re-encode produces MPEG-4 Part 2, VP8, VP9, or Theora rather than H.264 or H.265
- whether the browser can do this without FFmpeg depends on the codecs it exposes through WebCodecs
- the encoded streams are copied when the file's codecs fit the target container, and re-encoded when they do not
What is an MTS file?#
An MTS file holds the same BDAV MPEG-2 transport stream as M2TS, written under the extension the AVCHD standard assigns to footage recorded straight onto a camcorder's memory card.
Keep footage as MTS straight off a camcorder while it's only being copied or archived, since re-encoding at that stage only costs quality for no benefit.
Convert MTS to MP4 before editing or sharing camcorder footage, since most editors and every modern device handle MP4 more smoothly than the camcorder's native transport stream.
What is an MP4 file?#
An MP4 file holds video, audio, subtitle and chapter tracks together in the MPEG-4 Part 14 container, the structure ISO standardised from Apple's QuickTime format and the way most video is stored and shared today.
Choose MP4 when the file has to play somewhere you do not control, which covers anything uploaded, emailed or handed to another person.
Convert an MP4 to something else when the destination is not a player: pulling out the audio, making a GIF, or moving into Matroska to keep several subtitle and audio tracks in one file.
MTS to MP4 questions people ask#
Why won't my MTS file import into my video editor?
Some editors read the AVCHD folder structure a camcorder card uses but choke on an MTS file copied out on its own, and others simply don't ship the H.264 decoder settings AVCHD needs. Copying the whole camera folder in through the editor's dedicated camera-import feature, or converting the MTS to MP4 first, usually clears it up.
What should I convert MTS to?
Convert MTS to MP4 for editing and playback outside camcorder-specific software. It carries the same H.264 video without the AVCHD packaging that trips up general-purpose editors and players.
What produces an MTS file?
MTS files come off consumer and prosumer camcorders recording in the AVCHD format, made by Sony, Panasonic, Canon, and others since 2006. The camera writes each clip into the memory card's AVCHD folder structure with the .MTS extension.
What's the difference between MTS and M2TS?
Nothing in the stream itself. Both are the same BDAV MPEG-2 transport stream; MTS is the extension the AVCHD camcorder standard uses for footage on a memory card, while M2TS is the extension Blu-ray Disc authoring and playback software uses for the same structure once it's on a disc.