AI-generated live captions let viewers follow your stream in real time. Enable captions when creating a live source, and the platform automatically transcribes spoken audio throughout your broadcast.
In this article:
Set up live captions
Walk through these steps to enable live captions on your stream.
Using a MUX source? MUX also supports live captions, but setup follows a different path. See MUX Live Source.
1. Create a live source with captions enabled
Go to Live Streaming > Live sources and click Create live source.
For Type, select Ravnur Media Services.
For Account, select your RMS account. If you have only one account, it's listed as default.
For Encoding, select Standard Passthrough.
For Ingest stream protocol, select RTMP or SRT.
Live captions are not available for RTSP protocol or adaptive bitrate encoding.
Fill in the Title and, optionally, the Description.
Under Captions, select Enable AI generated live captioning, then select the language of your stream's spoken audio.
Leave the low latency checkbox off. Click Create Live Source.
2. Create a channel and schedule your event
Create a live channel and associate it with the live source you just created.
Optional: to include captions in the VOD recording, enable Generate captions for the VOD asset in post-production settings and select the language of the audio track - the same language you selected when enabling live captions.
3. Go live
Start your event from the Control Room. Captions become active as soon as the preview starts - check the preview to confirm they're running - and they'll stay active throughout the broadcast.
Encoder settings for live captions
These settings are required for the AI transcription to work correctly. The paths shown follow OBS Studio's Settings menu structure - if you use a different encoder, locate the equivalent settings and apply the same values.
Setting |
Value |
| Output tab > Keyframe interval | 2 s |
| Output tab > Max B-frames | 0 |
| Output tab > Audio tab > Audio bitrate | Set to any non-empty value |
| Audio tab > Sample rate | Set to any non-empty value |
| Audio tab > Channels | Set to any non-empty value |
Requirements
Live captions work with specific source types and account settings, and encoder settings - verify these before going live.
Do |
Don't |
| ✓ Use RTMP or SRT passthrough with an RMS source. | ✗ Use RTSP or adaptive bitrate sources. |
| ✓ Use standard latency. | ✗ Use low-latency events. |
| ✓ Use a DVR-enabled live source (RMS accounts have DVR enabled by default). | ✗ Use a no-recording account. |
Live captions do not automatically carry over to the VOD recording. To include captions in the recording, enable Generate captions for the VOD asset in post-production settings, or generate captions after the event.