How Subtl works on a call

Where the audio comes from

macOS lets an app with permission read the sound other apps are playing, and read your microphone. Subtl uses both — the other side from system audio, you from the microphone — which is why it works in every call app and why the two voices can be told apart.

What happens to a sentence

Four steps, each of which you can switch off.

• Recognition turns speech into text as it is spoken, in the cloud or on your Mac.
• Translation turns each finished line into your language.
• The prompter decides whether a line needs an answer and, if so, drafts one.
• Saving writes the line into your local history.

Why the windows are not in your screen share

The two windows are marked as protected content, the same mechanism a password manager uses. A screen share or screen recording made on your Mac does not include them.

The permissions macOS will ask for

Microphone, and Screen & System Audio Recording. The second is the permission macOS uses for any audio capture; Subtl reads audio only and never the picture.

Setting up a meeting

Optional, and worth two minutes before an important call: your role, the goal, who you are talking to, a glossary and documents. The prompter's answers then quote your facts instead of generic phrases.