Convert AVCHD to MP4 on Mac: 3 Methods

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. Three solid routes cover most Mac jobs: GetCompress for batch cards, QuickTime for one clip, and FFmpeg for Terminal remux.

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.

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 .

Method 1: GetCompress

Best for: event offloads, full card copies, and portals that list a hard megabyte cap.

1. Copy MTS files out of the nested AVCHD tree into a plain folder.
2. Open GetCompress and drop the folder into the queue.
3. Choose MP4 output, set resolution and quality, or set an exact target file size when the portal states a limit (video only).
4. Trim in the preview if you only need one segment from a long take.
5. Export, then upload or hand off the MP4 copies.

Save a preset such as “1080p client highlight” so you can reuse it next time. Folder monitoring can watch an offload folder after each card ingest.

Method 2: QuickTime

Best for: One highlight clip when you do not need a batch queue.

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

Export re-encodes, which takes longer than remux but produces a clean MP4 for sharing.

Limitation: QuickTime does not batch an entire event card.

Method 3: FFmpeg in Terminal

Best for: Remux speed, folder loops, and interlaced sources.

Install FFmpeg with Homebrew if needed:

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 .

Limitation: You maintain the commands yourself.

Which method should you use

When a QuickTime export is enough

QuickTime can finish a single highlight when the exported MP4 lands under the limit after a trim and a 1080p or 720p export.

GetCompress also helps when you offload many MTS clips after each event, need a reusable preset, or must hit an exact video target file size. Processing stays on your Mac. It does not replace Final Cut or Premiere. For the Windows workflow, see AVCHD to MP4 on Windows .