[AI in Practice] Gemini 3.5 Transcribe: Real-time Transcription and Speaker Diarization in a macOS Meeting Translation App

Previously

I have a macOS App I use myself, gemini-live-translate-macos. It uses ScreenCaptureKit to directly capture audio from a specified App, eliminating the need for virtual sound cards like BlackHole. It then sends the audio to the Gemini Live API for real-time translation, outputting Traditional Chinese subtitles while playing Chinese audio. I've written two posts about the development process: the first one was about building it from scratch using AGY CLI, and the second one was about using Claude Code to take it from "functional" to "user-friendly."

The starting point for this new addition was simple: I saw a document for "Real-time Transcription" added to the Live API. Since I was already connected to the Live API, I thought adding a pure transcription mode would just be a matter of changing a few parameters.

However, after checking the documentation, I realized that Google released two models with very similar names but very different capabilities at once. The specific feature I actually wanted (speaker diarization) wasn't available at all on the model I originally thought it was.

Two Models with Names Differing by Only Two Words