M2TS to MKV Converter

Convert M2TS to MKV: What This Tutorial Covers

M2TS is the transport stream that Blu-ray discs and AVCHD camcorders write — each 188-byte MPEG-2 transport packet carries an extra 4-byte header, giving the 192-byte BDAV packets stored in a BDMV/STREAM folder. MKV is Matroska, the open container the IETF published as RFC 9559 in October 2024. This tutorial covers the conversion itself and then the question everyone actually searches for — whether you can do it "without losing quality" — because the honest answer has a catch that changes which settings you should pick.

How to Convert M2TS to MKV

1. Upload Your M2TS File: Drag and drop the .m2ts clip onto the page or click "+ Add Files". Batch is supported, so a folder of camcorder clips can go through in one run with identical settings.
2. Set the Video Codec and Quality Preset: Video Codec starts on H.264, matching what most M2TS sources already contain; H.265 is there if you want a smaller archive. File Compression starts on Quality Preset with Very High (Recommended) selected, which is the setting to keep for archival work.
3. Choose the Audio Codec, resolution or Trim: Audio Codec starts on AAC; switching it to AC3 keeps a Dolby soundtrack in the Dolby family instead of converting it to a different lossy codec. Video resolution starts on Keep original. Set Trim to Time Range with a Start time and Duration if you only need one section.
4. Convert and Download: Click "Convert" and save the .mkv file. No sign-up, no watermark.

Walk-through: What "Without Losing Quality" Really Means Here

Most people arrive at this conversion expecting a remux — lifting the H.264 video out of the transport stream and dropping it into Matroska untouched, byte for byte, in a few seconds. That is not what happens here. Our pipeline decodes and re-encodes the video on every conversion; there is no stream-copy path, even when the output codec is the same H.264 the source already used. The result is one generation removed from the original: at Very High the difference is hard to see, but the output can only match the source or fall slightly short, never improve on it.

That distinction changes how you should drive the settings:

• To stay as close to the source as possible: leave Video Codec on H.264, File Compression on Quality Preset at Very High, and Video resolution on Keep original. Every one of those is already the starting state, so the default path is also the highest-fidelity path.
• To shrink a Blu-ray-bitrate file: switch Video Codec to H.265, or use Constant Bitrate / Variable Bitrate and set a rate well below the source's. AVCHD records up to 24 Mbit/s (28 Mbit/s in the 1080p50/60 modes), so there is usually room to halve it before artifacts show.
• To hit a storage budget exactly: Specific file size takes a number in bytes, kilobytes or megabytes, and Constraint Quality caps the peak bitrate while letting quieter scenes use less.
• To keep the audio from taking a second hit: set Audio Codec to AC3 rather than leaving it on AAC, so a Dolby Digital track isn't re-encoded from one lossy codec into another.
• If you truly need zero re-encoding: use a stream-copy remuxer instead. MKVToolNix is a set of tools for creating, altering and inspecting Matroska files on Windows, Linux and other Unix systems, and FFmpeg's stream-copy mode does the same job from a command line.

Picking the Audio Codec for an M2TS Soundtrack

M2TS vs MKV at a Glance

Common Errors and How to Fix Them

• "The MKV isn't sharper than the M2TS" — expected. This is a re-encode of already-compressed video: the output matches the source at best. Keep Quality Preset at Very High to make the gap negligible.
• "Fine horizontal lines through moving objects" — the source is interlaced 1080i and the combing is baked into the frames. No deinterlacing is applied during conversion, so remove it in a desktop editor if it bothers you. Progressive sources are unaffected.
• "My smart TV won't play the MKV" — Matroska support on TV hardware is inconsistent. Convert M2TS to MP4 instead when the target is a TV, a phone or a social upload.
• "The picture looks horizontally squeezed" — the source is 1440×1080 anamorphic AVCHD, which stores non-square pixels. No pixel-aspect correction is applied, so set Width × Height to 1920×1080 under Video resolution to bake in the correct shape.
• "The upload is taking forever" — a Blu-ray-rate stream is several gigabytes per feature. Trim to the segment you need with Video Cutter first, or convert clips a few at a time.

When This Doesn't Work

The hard stop is copy protection: retail Blu-ray discs are encrypted with AACS and frequently BD+, and an encrypted stream cannot be decoded by a conversion tool. This page works on M2TS files you can already open — your own AVCHD footage, unprotected recordings, or discs decrypted separately with software you own. Two softer failure modes are worth knowing. A clip copied off a camera card mid-write can have a damaged stream index that scrubs partially in a player but fails to convert cleanly; re-copy it from the source. And camcorders that split a long recording into sequential clips give you several files that need joining in a video editor first — converting them one at a time produces several MKVs, not one continuous archive. If your files carry the camcorder spelling, MTS to MKV is the identical conversion, and the M2TS converter hub lists the other output formats this footage can go to.

Frequently Asked Questions

Is converting M2TS to MKV a remux or a re-encode?

A re-encode. Our pipeline decodes the video and encodes it again on every conversion, so even an H.264 source going to an H.264 MKV is one generation removed from the original rather than a byte-for-byte copy. At the Very High preset that generation is very hard to spot in normal viewing. If you need the original bitstream preserved exactly, use a stream-copy remuxer such as MKVToolNix instead — that is a different operation from what any transcoding service does.

What happens to a Dolby Digital or DTS audio track?

By default it becomes AAC, which is a second lossy generation. Setting Audio Codec to AC3 avoids the codec change and keeps a Dolby track in Dolby form, including its 5.1 channel layout, which Matroska carries natively and VLC, Kodi and Plex all decode. DTS is also selectable, as are FLAC and the PCM variants if you want the audio stored losslessly — worth it when the source was Linear PCM, less useful when it was already compressed.

Do Blu-ray chapters and subtitles carry over into the MKV?

Matroska itself supports chapters, multiple audio tracks and soft subtitles — that is much of why it is the archival favourite. What survives depends on the source, and a lone .m2ts clip is a weak starting point: on a disc the chapter marks and playlist structure live in sidecar files next to the stream rather than inside it, so converting one clip in isolation cannot recover them. A single AVCHD camcorder clip normally has one audio track and no subtitles anyway. The advantage of MKV is headroom — you can add subtitle or audio tracks to the archived file later without converting it again.

Why archive camcorder footage as MKV instead of leaving it as M2TS?

Because a .m2ts is only half a file in practice. It expects the BDMV/AVCHD folder tree around it — playlist and clip-info sidecars that many backup routines quietly drop — and plenty of editors and players refuse the bare stream. One self-contained .mkv per clip is easy to name, store, verify and migrate, and Matroska is a published open specification rather than a disc-authoring convention.

Which video codec should I choose for a 1080i AVCHD clip?

H.264 is the default and the safest answer: it is what the camcorder recorded, so the encoder is working with material its own compression model suits, and every player handles it. Choose H.265 when storage matters more than compatibility — it typically reaches similar quality at a lower bitrate, at the cost of slower encoding and patchier support on older hardware. The legacy options in the list (MPEG-2, MPEG-4, Xvid, WMV) exist for specific device targets and will produce larger files at lower quality.

Will interlaced 1080i footage be deinterlaced during conversion?

No. No deinterlacing is performed anywhere in the pipeline, so if the source fields were combed the output keeps them combed. That is fine for archiving, since the field information is preserved rather than guessed at, and a player or editor can deinterlace on playback. If you need progressive frames baked in, deinterlace in a desktop editor before or after this conversion.

Should I use MKV or MP4 for this footage?

Choose MKV for archiving, media servers such as Plex and Jellyfin, multiple audio tracks and subtitles. Choose M2TS to MP4 for phones, smart TVs, browsers and social uploads, where MP4 support is close to universal and MKV is hit-and-miss. Both wrap the same re-encoded H.264 video, so the decision is entirely about where the file has to play.

What happens to my file after conversion?

It is uploaded over an encrypted connection, processed on our servers and deleted automatically after a few hours along with the MKV — no sign-up, no watermark, never shared or made public. The practical constraint is upload size and time rather than the conversion: Blu-ray-rate M2TS files are large, so trimming first keeps the transfer manageable.