Convert AVCHD to MP4 on Mac

AVCHD footage from Sony, Panasonic, and Canon camcorders arrives as MTS or M2TS files inside a dated folder structure. Editors, upload forms, and collaborators expect plain MP4 instead. You notice when Final Cut imports slowly, when a client portal rejects MTS, or when you need to share one interview clip without handing over an entire PRIVATE card dump. Converting locally keeps raw event footage on your machine and produces files phones and web tools can play.

AVCHD vs MP4

AVCHD is a camcorder format that stores H.264 video (often AVC High Profile) with AC-3 or AAC audio in MTS containers on disc or SD cards. MP4 is the same codec family in a container every app accepts.

	AVCHD (MTS)	MP4
Common source	Consumer camcorders, event videography	Web, phones, editors
Folder layout	Nested AVCHD / BDMV structure	Single files
Upload forms	Often rejected	Usually accepted
Best first step	Remux or re-encode to MP4	Already compatible

In practice, AVCHD shows up in wedding archives, conference recordings, and school event videos. MP4 is what you send for client review, social drafts, and ticket attachments. Because the video is often already H.264, remux with -c copy is fast when audio codecs cooperate. When editors choke on AC-3 or interlaced flags, re-encode audio to AAC and deinterlace if needed.

See HEVC to H.264 on Mac when your camcorder exports HEVC instead. When size limits matter, see the video compression guide .

Export in QuickTime

QuickTime Player opens many MTS files copied to disk when you drag a single clip out of the card structure.

1. Copy individual MTS files to a plain folder (not only the nested AVCHD tree) so apps find them reliably.
2. Open the clip in QuickTime Player.
3. Edit → Trim (⌘T) to mark in and out points for the section you need.
4. File → Export As → 1080p (or 4K when the source is AVCHD at that resolution).

Export re-encodes, which takes longer than remux but produces a clean MP4 for sharing. For a full card with dozens of clips, use FFmpeg batch mode instead of exporting one by one.

Situation	Export choice
One highlight for a client	1080p after trim
Full interview	1080p, trim dead air first
Portal with a hard MB cap	720p export or compress after

QuickTime does not watch a camera card for new clips. Use FFmpeg or GetCompress for batch event workflows.

Convert with FFmpeg

FFmpeg in Terminal handles MTS remux and batch event folders. Install through Homebrew:

brew install ffmpeg

Fast remux when video is already H.264:

ffmpeg -i input.mts -c copy -movflags +faststart output.mp4

When audio fails or editors reject the file, re-encode audio to AAC:

ffmpeg -i input.mts -c:v copy -c:a aac -b:a 192k -movflags +faststart output.mp4

Full re-encode for maximum compatibility:

ffmpeg -i input.mts -c:v libx264 -crf 20 -preset medium \
  -c:a aac -b:a 192k -movflags +faststart output.mp4

Batch every MTS in a folder:

mkdir mp4-out
for f in *.MTS *.mts; do
  [ -f "$f" ] || continue
  ffmpeg -i "$f" -c copy -movflags +faststart \
    "mp4-out/${f%.*}.mp4" 2>/dev/null || \
  ffmpeg -i "$f" -c:v libx264 -crf 20 -preset medium \
    -c:a aac -b:a 192k -movflags +faststart \
    "mp4-out/${f%.*}.mp4"
done

For interlaced AVCHD, add -vf yadif before libx264 if you see combing on motion. For MOV exports from newer cameras, see MOV to MP4 on Mac .

Using GetCompress

GetCompress fits recurring convert AVCHD to MP4 on Mac work when you offload many MTS clips after each event or when upload forms enforce size caps.

Drop MTS files or a folder of card copies into the app. Choose MP4 output, set resolution and quality, or use target file size when the portal states a limit. Trim in the preview before export when you only need one answer from a long interview.

Useful workflow pieces in GetCompress:

• Batch queue: process an entire card copy without opening each MTS in QuickTime.
• Presets: save “1080p client highlight” or “720p review” for repeat event work.
• Preview and trim: mark the usable segment before export when the camera ran continuously.
• Folder monitoring: watch an offload folder and auto-convert new MTS files when you ingest cards after each shoot.
• Local processing: keep unreleased event footage on your Mac instead of uploading raw AVCHD online.
• Target file size: hit portal megabyte limits without guessing CRF values in Terminal.

After conversion, if the MP4 is still too large, adjust quality or resolution in the same window rather than starting over.