Your files stay on your Mac.
Convertessa reads AVCHD MTS files directly from your camcorder card and rewrites them into the Matroska MKV container. MKV is recognised by virtually every video editor and media player, making your footage immediately usable without re-archiving. The entire process runs on your Mac — no upload, no cloud, no waiting.
Drag individual MTS clips or a whole AVCHD folder into Convertessa. Add as many files as you need — it handles batches and nested folders in one go.
Choose Matroska MKV from the output format list. Set quality to balance file size against fidelity before you convert.
Click Convert. Convertessa processes every clip locally and saves MKV files alongside the originals. Nothing leaves your Mac.
Images, audio, video, documents, archives and eBooks — all converted natively, right on your Mac.
Pick a format you have — see everything Convertessa can turn it into.
Convert hundreds of files at once with per-type group defaults and individual overrides.
First-class support for HEIC, AVIF and WebP — encode and decode, both ways. Read JPEG XL and a dozen more modern formats too.
Drop files anywhere on the window. Native, instant, and exactly what you’d expect on a Mac.
Dial in compression, resolution and bitrate. Keep originals pristine or shrink for sharing.
Never overwrite a file by accident. Convertessa appends safe suffixes automatically.
Every job is logged locally. Re-run a previous conversion or revisit recent outputs in a click.
Bundle your converted files straight into a single ZIP, TAR or 7z — packaged and ready to share the moment a job finishes.
Right-click any file in Finder and choose Convert. A Quick Action handles it on the spot — no need to open the app first.
Shrink Convertessa to a tidy mini window that tucks into a corner — just a drop zone and a format picker for quick, one-off conversions.
No cloud. No account. No upload. Every conversion happens entirely on-device, using the power already in your Mac. What you convert is nobody’s business but yours.
Script conversions, wire them into your build, or batch a folder from the terminal. The same engine, no GUI required.
Read the full CLI documentation →Shrink Convertessa down to a small, focused window — drop, convert, done, with your recent conversions one click away.
macOS 14+ · Apple Silicon & Intel
New formats, new features, and fixes — every release, on the record.
Yes. Point Convertessa at the folder containing your MTS files — or the root of the AVCHD card — and it converts every clip in one pass. From the command line: convertessa ./AVCHD/ --to mkv.
That depends on the quality setting you choose. At maximum quality the output is visually lossless; lower settings shrink the file at the cost of some fidelity. Convertessa preserves the original resolution at every quality level.
No. Reading the MTS file, encoding, and writing the MKV all happen on your Mac. Your footage never leaves your machine.