Your files stay on your Mac.
AC-3 (Dolby Digital) is a surround-audio format common in DVDs, Blu-rays, and broadcast streams. Convertessa decodes each AC-3 stream and re-encodes it as Opus — an open, royalty-free codec built for efficient compression at high fidelity. Every file is processed locally on your Mac; nothing is uploaded.
Drag one AC-3 file or an entire folder onto Convertessa. Batch mode processes every file in the folder in a single pass.
Pick Opus from the output format list. Because Opus is a lossy format, you can also set quality to balance file size against audio fidelity before converting.
Click Convert. Convertessa works entirely offline — no internet connection required and your audio never 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. Convertessa preserves the channel layout from your AC-3 source — stereo, 5.1, and other configurations are carried through to the Opus output.
Yes. Opus is a lossy format, so Convertessa lets you set quality before converting. Higher quality produces larger files; lower quality reduces file size.
No. Convertessa runs entirely offline on your Mac. Your AC-3 files are never uploaded — conversion happens locally with no internet connection needed.