AVCHD to M2TS Converter

AVCHD to M2TS Converter

An AVCHD recording and an .m2ts file are the same family of thing — H.264 video inside an MPEG-2 transport stream — so it is fair to ask what a converter could possibly change. The answer is more concrete than most pages admit: the .m2ts extension switches the transport-stream muxer into BDAV mode, which changes the packet framing, the packet identifiers and the file size. This page shows exactly what changes, byte for byte, and how to set the audio so the result is closer to something a Blu-ray-style player will accept.

What the M2TS Extension Actually Changes

We ran one source through the same encode twice, changing only the output extension. The differences are not cosmetic:

The 4-byte arrival-timestamp prefix on every 188-byte packet is where the extra size comes from — 4/188, or about 2.1 %. Nothing about the picture or the sound is different; the wrapper is. That is the whole story of this conversion, and it is why renaming a file between the two extensions is not equivalent to running it through here.

How to Convert AVCHD to M2TS

1. Upload Your AVCHD File: Drag your .avchd file onto the page or click "+ Add Files". This page accepts files named .avchd only — a camcorder clip still called .MTS is rejected with a pointer to the right tool, so use MTS to M2TS for those. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared or made public.
2. Set the Video Codec and Quality Preset: Video Codec opens on H.264, which matches what AVCHD already carries; H.265, MPEG-1, MPEG-2, MPEG-4, DivX and Xvid are also offered but move you away from anything a Blu-ray-style player expects. Quality Preset opens on "Very High (Recommended)", with seven rungs from Highest to Lowest.
3. Choose the Audio Codec: This is the setting that matters most here. The dropdown opens on AAC, and also offers AC3, EAC3, DTS (DCA), MP2 and MP3. The AVCHD specification allows only Dolby AC-3 or linear PCM, so AC3 is the choice that keeps the file legal-looking to AVCHD-aware players; AAC is fine for computer playback.
4. Set Resolution or Trim, Then Convert: Video resolution opens on "Keep original"; percentage, height presets from 4320p down to 144p, and explicit Width, Height or Width × Height are all available. Trim → Time Range takes a start time and a duration in seconds or HH:MM:SS.sss. Click Convert to download.

Rate Control on This Page

Two things worth knowing before you touch these. The server always re-encodes — there is no pass-through path — so an AVCHD clip that is already H.264 loses a generation of quality whatever you pick. And the Quality Preset ladder asks the encoder for a proportion of the source bitrate, with the top rungs sitting above 100 %, so leaving everything alone on an already-efficient AVCHD stream can produce a larger file than you started with.

Frequently Asked Questions

Is an M2TS file just an AVCHD file with a different name?

Very nearly, but not exactly. Both hold H.264 video in an MPEG-2 transport stream. The difference is framing: BDAV .m2ts wraps each 188-byte transport packet in a 192-byte source packet with a 4-byte arrival timestamp, and uses Blu-ray's reserved packet identifiers. A plain rename does not add those bytes, so software that genuinely parses BDAV framing will reject a renamed file — while software that just probes the stream will open either one happily.

Why is the M2TS output slightly bigger than the source?

Two reasons stack. The BDAV framing itself adds 4 bytes to every 188-byte packet, which is about 2.1 % on its own. On top of that the conversion re-encodes the video, and the default Quality Preset targets a proportion of the source bitrate rather than matching it exactly. If size matters, switch to Constant Quality and raise the CRF value, or use Specific file size to name a target directly.

Will my Dolby AC-3 5.1 surround track survive?

Only if you ask for it. The Audio Codec dropdown opens on AAC, which re-encodes your AC-3 track into AAC — playable everywhere on a computer, but no longer the codec AVCHD specified. Selecting AC3 keeps the output in the Dolby Digital family, which is one of only two audio codecs the AVCHD specification allows — the other being linear PCM. In our testing an AC-3 5.1 source re-encoded to AC-3 muxed into the .m2ts cleanly at 448 kbit/s with the 5.1 layout intact.

Can I burn the result straight to a Blu-ray or AVCHD disc?

No. A single .m2ts is a stream file, not a disc structure. An AVCHD disc or card needs the whole BDMV folder tree — BDMV/STREAM, BDMV/PLAYLIST, BDMV/CLIPINF and the index files — which an online converter cannot build. Use an authoring application to assemble the folder layout, and feed it a stream whose audio is AC-3 or LPCM rather than AAC.

My camcorder clip is called .MTS — can I upload it here?

Not on this page. The upload validator matches the extension exactly and this page is scoped to .avchd, so an .MTS file is rejected before it uploads and you are shown the tool that does take it. Go to MTS to M2TS instead — it is the same conversion with the right input scope.

Does converting to M2TS fix a clip my editor refuses to import?

Sometimes, but not for the reason people expect. Re-encoding writes a clean, freshly indexed stream, which does help with a clip that was interrupted mid-recording. What it does not do is change the codec pairing, and H.264 plus AC-3 in a transport stream is exactly the combination that older editors choke on. If the goal is editing rather than disc-style playback, AVCHD to MP4 is the more useful target.

Is the interlacing from my camcorder removed?

No. There is no deinterlacing anywhere in this pipeline, so if your AVCHD clip was recorded in a 1080i mode the combing stays baked into the output frames. That is usually the right default for a transport-stream target, since the field structure is what a disc player expects. If you want progressive frames for editing or web use, deinterlace in an editor after converting, or shoot in one of AVCHD's progressive modes.

What frame sizes and bitrates make sense for the output?

Leave Video resolution on "Keep original" unless you have a reason not to — AVCHD's HD modes are 1920 × 1080 or 1280 × 720, and nothing downstream gains from resampling them. If you do resize, note that the height presets set the height only and let the width follow the source aspect ratio, and that any resize flattens the stored pixel aspect ratio to 1:1, which matters on anamorphic sources. For bitrate, AVCHD's own ceiling is in the 24–28 Mbit/s region, so there is little point asking for more than that.

Can I convert several clips from one shoot at once?

Yes — queue them together and they are all processed with the same settings, each producing its own .m2ts. What the tool will not do is join them. Camcorders split long recordings into separate stream files because the card's FAT32 filesystem caps a single file at about 4 GB, and each segment is a complete transport stream in its own right. To rejoin a split take, import the segments into an editor after converting.