M2TS to MKV Converter

Convert M2TS to MKV: What This Tutorial Covers

M2TS is the BDAV MPEG-2 transport stream that Blu-ray Discs and AVCHD camcorders wrap their high-definition video in — H.264 (or, on older Blu-rays, MPEG-2 or VC-1) video paired with Dolby Digital (AC-3), DTS, or Linear PCM audio. This tutorial is for anyone rescuing that footage into MKV (Matroska), the open container the Matroska project began in December 2002 and the IETF standardized as RFC 9559 in October 2024. It walks through the conversion and then explains plainly what happens to your streams — because the most-searched question about M2TS to MKV is "can I do it without losing quality?", and the honest answer here has a catch worth understanding before you start.

How to Convert M2TS to MKV

1. Upload Your M2TS File: Drag and drop your .m2ts clip onto the page or click "+ Add Files". Batch is supported, so you can drop the whole BDMV/STREAM folder from a disc or camcorder and convert each clip with the same settings.
2. Set the Quality Preset and Video Codec: Open Advanced Options. The Quality Preset defaults to "Very High (Recommended)", which is the right archival choice. Video Codec defaults to H.264 (matching most M2TS sources); switch to H.265/HEVC for a smaller file at similar quality, or pick Constant Quality and enter a CRF if you tune by hand.
3. Adjust Audio Codec, Resolution, or Trim (optional): Audio Codec defaults to AAC — set it to AC3 to carry a Dolby Digital track without converting it to a different lossy format, or FLAC for a lossless audio re-encode. Leave Video Resolution on "Keep original" to preserve the source frame size, or use Trim → Time Range to keep just one segment.
4. Convert and Download: Click "Convert" and download your MKV file. No sign-up, no watermark.

Walk-through: Re-encode vs. Remux — The Catch Worth Knowing

Almost every search for this conversion is phrased "M2TS to MKV without losing quality", and it leads people to expect a remux: lifting the H.264 video out of the transport stream and dropping it into Matroska untouched, bit-for-bit, in seconds. This converter does not do that — it re-encodes the video as it passes through the pipeline, even when the output codec is the same H.264 the source already used. The result is therefore one generation removed from the original: at the default "Very High" preset the difference is very hard to see, but the output can only match the source or drop slightly, never improve.

That is a real distinction, so here is how to get the closest thing to lossless out of a re-encoding tool — and when to reach for a true remuxer instead:

• Want the result as close to the source as possible: keep the Quality Preset on "Very High", or pick Constant Quality and set CRF to 18 on H.264. Leave Video Resolution on "Keep original".
• Want to keep the audio untouched: the default audio output is AAC, so a Dolby AC-3 track is re-encoded from one lossy format to another. Set Audio Codec to AC3 to avoid that lossy-to-lossy step, or to FLAC/PCM if you want a lossless audio track in the MKV.
• Want a smaller archive: switch Video Codec to H.265/HEVC or raise CRF a few points, accepting a little detail loss for size.
• Want a genuinely lossless container swap (zero re-encode): that needs a stream-copy tool. MKVToolNix is free and open-source (Windows and Linux), and FFmpeg's -c copy does the same from the command line. For most Plex and editing uses a high-quality H.264 re-encode is visually indistinguishable, but if you need the bytes preserved exactly, those are the right tools.

Common Errors and How to Fix Them

• "My MKV doesn't look any sharper than the M2TS" — Expected. This is a re-encode of already-compressed video, so the output matches the source at best and never exceeds it. Use the "Very High" preset or CRF 18 to keep the difference negligible.
• "The motion looks combed or shows fine horizontal lines" — Older Blu-ray and AVCHD footage is often interlaced (1080i). Combing artifacts on a progressive screen come from the source field order, not the conversion; deinterlacing in a dedicated editor cleans it up. Progressive (1080p/720p) sources are unaffected.
• "My player won't open the MKV" — VLC, mpv, Kodi, Plex, and Jellyfin handle Matroska well, but some smart TVs and older hardware players don't. If a specific device chokes on MKV, convert M2TS to MP4 instead — MP4 is the broader device-compatibility pick.
• "The file is too large to upload" — A Blu-ray M2TS can run 12-18 GB for a full feature at disc bitrates, so a long clip may take a while to upload over your connection. Trim to the chapter you need first, or convert a few clips at a time rather than a whole disc at once.

When This Doesn't Work

The biggest hard stop is copy protection. Commercial pre-recorded Blu-ray discs are almost always encrypted with AACS (and sometimes BD+), and the M2TS streams on them cannot be read or converted while that protection is in place — conversion tools cannot legally bypass it. This converter only works on M2TS files you can already open: your own AVCHD camcorder footage, unprotected disc recordings, or discs already decrypted with separate ripping software. Beyond DRM, a partially corrupted M2TS — common when a card was pulled before the camcorder finished writing — may be unreadable even if a player can scrub part of it, and clips a camcorder spanned across multiple files at the 2 GB/4 GB mark may need rejoining first. Because .m2ts and .mts are the same BDAV stream with different spellings, the MTS to MKV converter does the identical job for camcorder-named footage.

Frequently Asked Questions

Is converting M2TS to MKV lossless, or does it re-encode the video?

It re-encodes. Even when the source is H.264 and the MKV output is also H.264, this converter decodes and re-encodes the video rather than copying the stream untouched, so the result is one generation removed from the original. At the "Very High" preset or CRF 18 the loss is minimal and hard to spot, but the output can only match the source, never improve on it. For a true zero-loss container swap you need a stream-copy remuxer such as MKVToolNix or FFmpeg's -c copy.

Can I convert the M2TS files from a commercial Blu-ray movie?

Only if they are not copy-protected. Commercial Blu-ray discs are almost always encrypted with AACS, and sometimes BD+, and those encrypted M2TS streams cannot be read or converted while the protection is in place — no conversion tool can legally bypass it. This converter works on M2TS files you can already open, such as your own AVCHD camcorder footage, unprotected recordings, or discs you have already decrypted with separate software. It cannot decrypt a protected disc for you.

What happens to a Dolby Digital (AC-3) or DTS audio track?

The default audio output is AAC, so a Dolby AC-3 track is re-encoded into AAC — a lossy-to-lossy step that adds a small amount of generational loss. To avoid that, set Audio Codec to AC3 so the audio stays Dolby Digital, which MKV carries natively and Plex, VLC, and Kodi all decode, keeping 5.1 channels intact. MKV also supports DTS, FLAC, and PCM; pick FLAC or PCM under Audio Codec if your source was Linear PCM and you want the audio kept lossless.

Why archive Blu-ray or camcorder footage as MKV instead of leaving it as M2TS?

MKV (Matroska) is an open, royalty-free container standardized by the IETF as RFC 9559, read by a wide range of players and editors, and built to hold multiple audio tracks, subtitles, and chapters in one self-contained file. M2TS clips normally live inside a BDMV/STREAM folder structure that is awkward to back up and easy to break if the folder tree is disturbed. A single .mkv per clip is far simpler to store, label, and migrate forward as hardware and software change over the years.

Will the MKV keep multiple audio tracks and subtitles from a Blu-ray M2TS?

MKV as a container fully supports multiple audio tracks, soft subtitles, and chapters — that is a large part of why it is favored for archiving. Whether they all carry over depends on what the converter exposes from the source stream; a single AVCHD camcorder clip typically has just one audio track and no subtitles, while a Blu-ray M2TS may carry several. The benefit of MKV is the headroom: even if only one track comes across, you can add alternate audio or subtitle tracks to the archived file later without re-converting.

Is M2TS the same as MTS, and should I use MKV or MP4?

.m2ts and .mts are the same BDAV MPEG-2 transport stream — .m2ts is the Blu-ray Disc and computer spelling, .mts is what AVCHD camcorders write on the card. The conversion is identical, so use MTS to MKV if your file ends in .mts. As for the container: choose MKV for archiving, media servers (Plex, Jellyfin, Kodi), multiple audio tracks, and subtitles; choose M2TS to MP4 for phones, smart TVs, social uploads, and the broadest device compatibility. Both wrap the same H.264 video — pick by playback target.

How are my files handled, and is there a size limit?

Your M2TS file is uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — no sign-up, no watermark, never shared or made public. In our testing the main practical limit is upload size and time rather than the conversion itself: a Blu-ray M2TS can be many gigabytes, so a long clip may take a while to upload even though the conversion that follows is quick. Trimming to the segment you need first keeps the upload manageable.