Turn audio from other apps into translated captions. Keep the video in its app, with subtitles beside it.
Made for iPhone. Inspired by Mimi.
Character & caption style illustration
TRY A LINE
Illustrative text · No recording or translation service
Osu.Let’s go a little further today.
When the rain stops, let’s take a walk.
01 / RECOGNITION & TRANSLATION
One caption window, two ways to process audio. Choose what fits your device and languages.
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.
iOS 18–25 supports available local recognition, without Apple translation.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 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.
Source preview · iOS 18+
Available 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.