Echo
Swift · macOS
Subtitles for anything your Mac plays.
A menu bar app that draws live subtitles over anything your Mac is playing, even video with no captions. On-device or cloud, with live translation.
The problem
Plenty of video and audio has no subtitles, or none in a language you read.
What it is
Echo lives in the menu bar and listens to system audio, never the microphone. It draws real-time subtitles in a transparent, click-through overlay above whatever you’re watching: YouTube, Netflix, VLC, a Zoom call.
Key features
- Three transcription engines: Apple on-device, WhisperKit, or a cloud API
- Live translation into the language you pick
- Per-app filtering, global shortcuts, and .srt or .txt export
- A movable, resizable overlay that remembers its place on each display
Stack
Engineering challenge
An overlay that stays smooth while it moves.
Echo’s subtitles float in a transparent, click-through window you can drag and resize over any app. Moving it used to make SwiftUI measure the caption text again, so I split the window’s position from the text layout and let size changes settle once per screen refresh. Measured with real mouse drags, the busiest moments on the main thread while moving fell from about 7.4 ms to 1.7 ms, and side resizing from 6.6 ms to 2.9 ms.
Nguyen Hoang · nguyenhoang0383833@gmail.com