Osu transcribes and translates audio from other apps into captions in a Picture in Picture window.
Made for iPhone. Inspired by Mimi.
Character & caption style illustration
TRY A LINE
Illustrative text · No recording or translation service
Osu.Don’t forget your umbrella.
When the rain stops, let’s take a walk.
01 / RECOGNITION & TRANSLATION
Alibaba Cloud can detect the spoken language. Apple processes audio on your iPhone, using languages supported by your device.
Auto-detect → Chinese
Detect the source language automatically and translate into Chinese by default, or choose languages manually. Requires a Model Studio API key for the Beijing region.
App audio is sent to Alibaba Cloud and counts toward your account usage.Processed on your iPhone
Select a source language and use supported on-device recognition. Apple translation requires iOS 26 and the appropriate language packs.
On iOS 18–25, Apple mode can show the original speech as text if on-device recognition is available. Translation requires iOS 26.02 / HOW IT WORKS
Compile on a Mac with Xcode and install on iPhone. An Apple signing team is required; Expo Go is not supported.
Add your Alibaba API key or select Apple local mode. Keys are stored in iOS Keychain.
Tap “开始听” (Start), select “Osu Audio” in the system broadcast panel, and confirm. Return to the video app. Close the caption window to stop.
Captions use Picture in Picture. Another app’s PiP can replace them and end capture, so keep video in its original app. Close iPhone Mirroring before broadcasting.
Preview · iOS 18+ · Build from source
You need to build and install Osu from source. No App Store or TestFlight release yet. App compatibility and long background sessions are still being tested.
No. Osu does not save audio or captions, and discards video and microphone samples. Apple mode processes audio locally; Alibaba mode sends app audio to the provider.
Support depends on your chosen service, device, and installed language packs. Alibaba mode can detect the source language; Apple recognition needs a manual choice. See the repository’s language guide.
The current product targets iPhone. See Mimi for desktop subtitles. Osu has no Android product release yet.