How to Add Live Captions & Translations to OBS (No Internet Required)

To add live captions to OBS: open http://{device IP}:8080/url.html on your ConferenceCaptioning device, customize how the captions or translations should look, copy the generated overlay URL, and add it to OBS as a Browser Source. Everything runs over your local network, so captions keep working with no internet connection.

Why run captions over your local network?

Cloud captioning tools stream every word to a data center and back, so they stall when a few thousand attendees crowd the venue Wi-Fi. ConferenceCaptioning turns your Mac, iPad, or iPhone into the AI captioning server: transcription and translation happen on the device in the room, and OBS reads the captions straight from it over the local network. No internet, and no hardwired internet line to rent from the venue.

Step 1: Start captioning and find your device's address

1. Open the ConferenceCaptioning app, connect your audio source (mixer, audio interface, Dante, or NDI), and start streaming.
2. Tap the Info icon in the app to see your device's local URL. It looks like http://192.168.0.100:8080/index.html.

Step 2: Design your captions with the live preview

1. On any computer on the same network, open that address with url.html in place of index.html, for example http://192.168.0.100:8080/url.html.
2. Choose captions or a translation, and set the text color, position, and background. The page shows a live preview as you go.
3. Copy the URL from the "AV Team Local URL Video Overlay" box.

Step 3: Add a Browser Source in OBS

1. In OBS Studio, click + under Sources and choose Browser. Name it "Live Captions".
2. Paste your overlay URL into the URL field and set the width to 1920 and height to 1080 (or your canvas size).
3. Click OK, then drag the source above your camera or slides in the source list so the captions sit on top.

Step 4: Transparent background or chroma key

The transparent background works out of the box: captions appear directly over your video with nothing else to set up. If you prefer a chroma key, as many AV engineers do:

1. Pick the green background on the url.html page and copy the new URL into your Browser Source.
2. Right-click the Browser Source, choose Filters, click + under Effect Filters, and add Chroma Key.
3. Leave the key color on Green and adjust similarity if any green fringe remains.

Step 5: Show and hide captions during the show

• Toggle the eye icon next to the Browser Source in OBS.
• Or start, stop, show, and hide captions from an Elgato Stream Deck or Bitfocus Companion, or from any browser at http://{device IP}:8080/control.html, without touching the captioning device.

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Pro Tips

1. Multiple languages: add one Browser Source per translation, each with its own URL from url.html, and put them in separate scenes or outputs.
2. Keep the address from changing: give the captioning device a static IP so your OBS URL keeps working from one event to the next. Here's how on a Mac.
3. Site can't be reached? If OBS runs on the same Mac, try the Localhost URL. On a different Mac, allow OBS under Settings > Privacy & Security > Local Network.
4. Text too small? Lower the Browser Source width (for example to 1280) and scale the source up on your canvas.
5. Mission-critical show? Add a backup Mac or iPad with hot-failover redundancy so captions switch over automatically if the primary device drops.
6. On Windows? The ConferenceCaptioning Chrome extension can send captions to OBS through its Local Network Display.

Frequently asked questions

Do I need an OBS plugin to show live captions?

No. ConferenceCaptioning uses OBS's built-in Browser Source. You paste the caption URL from the url.html page and OBS displays live captions or translations as an overlay.

Do OBS captions need an internet connection?

No. The captioning device transcribes and translates on-device and serves captions over your local network at http://{device IP}:8080, so OBS keeps showing captions even if the venue internet goes down.

Can I show translations in OBS instead of captions?

Yes. On the url.html page, choose which translation to display. Add one Browser Source per language if different screens or streams need different languages.

Should I use a transparent background or a chroma key?

Both work. The transparent background drops straight onto your video with no extra setup. Many AV engineers prefer a green chroma key background with OBS's Chroma Key filter, because it behaves predictably across switchers and outputs.