Your files stay on your Mac.
Converting Flash FLV to AC-3 extracts the audio track and re-encodes it as Dolby Digital AC-3. The resulting file plays on Blu-ray players, AV receivers, and any AC-3-capable device. Everything runs locally — no upload, no cloud, no file size cap.
Drag one FLV file or an entire folder onto Convertessa. Batch mode picks up every Flash file in the folder and queues them in one pass.
Choose AC-3 from the output format list. Because AC-3 is a lossy format, you can set quality to dial in the right balance between file size and audio fidelity.
Click Convert. Convertessa extracts and encodes the audio track on your Mac — no network connection required.
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.
No. Convertessa runs entirely on your Mac. Your FLV files are never sent to any server.
Yes. Drop a folder onto Convertessa or run convertessa /your/folder --to ac3 — every FLV file in the folder is converted in one pass.
Use the quality slider in Convertessa before converting. A higher quality setting preserves more of the original audio at the cost of a larger file.