AVCHD to MP4 Converter

How to Convert AVCHD to MP4 Online

1. Upload Your AVCHD Files: Drag and drop the .MTS or .M2TS files from your camcorder's BDMV/STREAM folder, or click "Add Files" to pick them from disk. Batch conversion is supported, so you can queue several clips from the same shoot and process them in one job.
2. Pick Quality Preset and Codec: The default is "Very High (Recommended)" with H.264 video and AAC audio — a safe match for editors and social platforms. Switch the Quality Preset to Highest, High, Medium, Low, or Lowest to trade size for quality, or expand Advanced to choose a different video codec (H.265/HEVC for ~50% smaller files at the same quality, VP9, AV1, MPEG-4) or audio codec (AAC, AC-3, MP3, Opus, FLAC, PCM).
3. Resize and Trim (Optional): Use the Video Resolution controls to keep the original 1920×1080, pick a preset (4320p down to 144p), enter a Width × Height, or scale by a Resolution Percentage. Trim by setting a Start time and Duration in seconds or HH:MM:SS.sss to extract a single clip from a long take.
4. Convert and Download: Click Convert. Files process in your browser session — no sign-up, no watermark, no upload to a third-party cloud.

Why Convert AVCHD to MP4?

AVCHD (Advanced Video Coding High Definition) was introduced in 2006 by Sony and Panasonic for HD consumer camcorders, and the first retail cameras shipped in 2007. The format wraps H.264 video plus Dolby AC-3 or linear PCM audio inside an MPEG-2 Transport Stream and stores the clips as .MTS files (renamed .M2TS after import) inside a BDMV/STREAM directory borrowed from Blu-ray. That tree is great for camcorder playback and terrible for everything else.

• Editor compatibility — Final Cut Pro, Premiere Pro, DaVinci Resolve, and iMovie all import AVCHD, but native AC-3 audio is often down-mixed or skipped on macOS, and AVCHD 2.0 1080/60p clips can stutter on lower-spec timelines. MP4 with H.264 + AAC drops straight onto any timeline without transcoding warnings.
• Social uploads — YouTube, Instagram, TikTok, Facebook, X, and LinkedIn all accept MP4. None of them accept raw .MTS or the BDMV folder structure; uploading without conversion fails or strips the file to audio only.
• Phone and tablet playback — iOS and Android can play H.264 MP4 in the native player. AVCHD typically needs VLC, Infuse, or another third-party app, and even then the clip-spanning behavior (long takes split into 2 GB / 4 GB chunks) shows up as separate files.
• Cloud and sharing — Google Drive, iCloud, and Dropbox preview MP4 inline; AVCHD shows up as a download-only blob. AirDrop and Messages will reject .MTS from non-Apple sources.
• Smaller files — Re-encoding a 28 Mbps AVCHD 2.0 1080/60p clip to 8–12 Mbps H.264 MP4 cuts file size by 60–70% with no perceptible quality loss in normal viewing.
• Future-proofing — Sony deprecated AVCHD in favor of XAVC S (MP4) starting in 2013, and most camcorder lines have been discontinued. New editors test against MP4 first; AVCHD support is legacy.

AVCHD vs MP4 — Format Comparison

Codec & Quality Preset Quick Guide

Frequently Asked Questions

My AVCHD audio is silent or down-mixed in iMovie or Final Cut — does this fix it?

Yes. AVCHD ships Dolby AC-3 audio that macOS handles inconsistently — Final Cut Pro X imports it but down-mixes 5.1 to stereo, and iMovie often refuses AC-3 entirely. Converting to MP4 with AAC audio (the default here) produces a track every Apple editor reads cleanly. If you specifically need to keep 5.1, choose AC-3 in the audio codec dropdown instead of AAC; the 5.1 channel layout is preserved into the MP4 container.

Can I convert without re-encoding the video to keep original quality?

Both AVCHD and MP4 carry H.264 video, so a true "stream copy" remux is technically possible and lossless — the bytes of the H.264 stream move into a new container without re-encoding. This online converter re-encodes on the Quality Preset you pick, which gives you control over file size and bitrate. If avoiding any quality loss matters more than file size, pick the Highest preset; the result is visually indistinguishable from the source even on a calibrated monitor.

Why are my camcorder clips split into multiple files?

AVCHD camcorders write to FAT32 SD cards, which cap a single file at 4 GB (2 GB on older cards). A long take auto-splits into sequentially numbered .MTS files (00001.MTS, 00002.MTS…) in BDMV/STREAM. Upload all the segments together — most editors and this converter treat each .MTS as its own clip. The split is at a fixed file-size boundary, not at a scene cut, so the audio and video continue across files without gaps; concatenating in any modern editor produces a seamless timeline.

Should I pick H.264 or H.265 for the output?

H.264 if you want maximum compatibility and zero playback friction — every browser, phone, TV, and social platform accepts it. H.265 (HEVC) if storage matters more than reach; it's roughly half the file size at the same visual quality. H.265 plays in Safari 11+, Chrome 107+, Edge with HEVC extension, and most 2017+ TVs and phones, but older Android devices, Firefox without hardware decode, and many web video tools still don't handle it.

Will AVCHD's 1080/60p (AVCHD 2.0) survive the conversion?

Yes. AVCHD 2.0 added 1080p50 and 1080p60 progressive modes at up to 28 Mbps in 2011, and modern Sony/Panasonic camcorders use these as the highest-quality setting. Set the Quality Preset to Very High or Highest and either keep the original resolution or pick the 1080p preset; the converter preserves the 50/60 fps frame rate and progressive scan.

What's the difference between .MTS and .M2TS?

It's the same data with two extensions. Camcorders write .MTS directly to the SD card. When you import to a Mac or Windows PC, some software (notably Sony PlayMemories and the AVCHD-aware Finder/Explorer) renames the file to .M2TS and may wrap it in extra metadata. Both are MPEG-2 Transport Streams carrying H.264 + AC-3, and this converter accepts either — see also MTS to MP4 for the same conversion targeted at the renamed extension.

Does it matter that AVCHD has been deprecated?

For converting existing footage, no — AVCHD plays fine and the spec hasn't changed. But Sony stopped releasing new AVCHD-only camcorders after 2013 (XAVC S took over) and Panasonic followed. If you're shooting today, your camera probably writes MP4 or XAVC S directly. AVCHD conversion is mostly a problem for libraries shot 2007–2018, and converting to MP4 future-proofs them against editor support eventually being dropped.

Can I convert a whole BDMV folder at once?

Upload the individual .MTS files from BDMV/STREAM/ rather than the parent folder. Browsers don't grant access to nested folder structures the way desktop software does, so the converter sees one file at a time. Select all the clips inside STREAM and drop them in together — batch processing handles them in parallel.

What other targets work better than MP4 for editing?

If you're going straight into Premiere or Resolve, MP4 with H.264 is the standard intermediate. For ProRes-style mezzanine workflows, AVCHD to MOV gives you a QuickTime container that pairs better with Final Cut. For lossless archival before re-encoding later, AVCHD to MKV wraps the same H.264 stream in a more flexible container. To shrink a finished MP4 further, run it through compress MP4.