LAPLACE Cap's STT feature is built on the Soniox real-time speech recognition API. It transcribes speech to text while you stream, and renders a subtitle view you can overlay in OBS
Features
- Built on Soniox's newest models, with low recognition latency, high accuracy, and strong results on the colloquial, code-switched speech typical of live streams
- Switch Soniox models from the Model dropdown on the STT tab. The newest real-time model,
stt-rt-v5, is the default - Choose a microphone input device, switching between the system's audio inputs
- Real-time translation converts the transcript into a target language and shows it in the subtitle overlay
- The subtitle overlay supports green, blue, and pink backgrounds, so a chroma key filter composites it straight onto the stream in OBS
- Language hints let you declare which languages may appear — a Chinese, Japanese, and English mix, for instance — to raise accuracy
- Context tuning, through a domain, a topic, and custom terms, markedly improves recognition of game titles, jargon, and personal names
LAPLACE Cap is moving to a multi-provider architecture. Pick a transcription provider under Real-time provider and Async (subtitle) provider on the General settings page. Soniox is the only option for now; more providers are coming
Usage
Setup
- Register at the Soniox console and get an API key
- Enter the Soniox API key on LAPLACE Cap's General settings page
Start Transcribing
- Switch to the STT tab
- Pick a Soniox model from the Model dropdown (
stt-rt-v5by default) - On first use, click Allow next to Microphone to grant microphone permission
- Click Start Recording to begin real-time transcription
- The transcript appears on the page as it arrives, and the subtitle overlay at the bottom updates with it
Microphone Devices
- Once permission is granted, the Microphone dropdown lists every available audio input device
- Pick a specific device, or leave System default to use the system's default microphone
- The refresh button beside the dropdown re-enumerates after a device is plugged in or out; if the selected device disappears, LAPLACE Cap falls back to the system default with a notice
- If permission is denied or the browser lacks support, the page shows the matching notice — re-authorize in the browser settings and reload the page
OBS Subtitle Overlay
Once recording starts, subtitles pin to the bottom of the browser window as an overlay, filled with the solid color you picked so a chroma key in OBS can knock it out:
- Choose the overlay background color on the right of the STT control bar (green / blue / pink)
- Add a Window Capture or Browser source in OBS pointing at the LAPLACE Cap page, and crop to the subtitle strip at the bottom
- Add a Chroma Key filter matched to that solid color for a transparent background
- With real-time translation on, the source text and the translation take two lines in the overlay
Context Tuning
Fill in the following under Context on the STT tab to lift recognition quality:
| Field | Description |
|---|---|
| Domain | The domain the content sits in, such as gaming, esports, or music |
| Topic | What this stream is specifically about, such as a game title or event name |
| Terms | Proper nouns, game character names, streamer nicknames, comma-separated |
| Text | Any extra context, such as recurring chat phrases or a fixed opening line |
The more specific the context, the better the results. It cuts misspellings sharply, especially for the character and ability names that come up constantly in game streams
Notes
- Real-time transcription reads the browser's microphone input. To transcribe system audio such as in-game voice, route that audio to a virtual microphone device at the OS level
- The Soniox API bills by usage — see the Soniox pricing page
- The API key is stored only in your local browser. LAPLACE Cap never uploads or logs it
Last updated on September 19, 2026