Subtitles
BigBlueButton can display subtitles during a meeting through two different methods: a manual live captioning plugin where a designated person types the spoken text in real time, and automatic transcription available in newer versions where the browser converts speech to text. Both options require specific server configuration.
Plugin vs. Standard Feature
It is important to understand that subtitles in BigBlueButton come in two forms:
- Manual live captioning — a separate plugin, not part of the standard BigBlueButton installation. Must be installed by the server administrator.
- Automatic transcription — available in newer BigBlueButton versions. Uses the browser's built-in speech recognition to convert spoken words to text in real time.
If the subtitle or captioning option is not available in your meeting, the feature may not be enabled on your server. This is normal for standard installations without the plugin.
Manual Live Captioning (Plugin)
When the manual captioning plugin is installed, a moderator can set up live subtitles as follows:
A moderator activates the subtitle plugin and designates a person responsible for captioning.
The designated captioner types the spoken text into a dedicated input field in real time.
The typed text appears as subtitles for all participants in the meeting.
Manual live captioning requires an additional person dedicated to typing. This makes it resource-intensive but provides high accuracy when performed by a skilled captioner.
Automatic Transcription
Newer versions of BigBlueButton can provide automatic transcription, where the browser converts speech to text without a dedicated captioner:
- The browser of the speaking participant processes the audio and converts it to text in real time.
- The transcribed text is then displayed as subtitles for all meeting participants.
- Availability and quality depend on the BigBlueButton version, browser capabilities, and server configuration.
Viewing Subtitles
Participants can enable the subtitle display in their personal settings, provided the plugin or automatic transcription is available on the server. Subtitles appear as an overlay in the presentation area.
Privacy Considerations
The automatic transcription feature uses the browser's built-in speech recognition, which has different privacy implications depending on the browser:
| Browser | Data processing |
|---|---|
| Firefox | States that transcription is performed locally in the browser without sending data to external servers. |
| Google Chrome / Chromium | Likely sends audio data to Google servers for transcription. This may offer better speed and accuracy but raises privacy concerns. |
| Safari | Apple does not provide clear documentation on how speech recognition data is processed. |
If your meeting involves confidential or sensitive content, consider the privacy implications of automatic transcription carefully. In Chrome-based browsers, audio data may be transmitted to external servers for processing.
Plugin Management at bbbserver
At bbbserver, the subtitle plugin is currently only activated after a support request. This is a deliberate decision due to the privacy considerations surrounding automatic transcription in different browsers, which neither BigBlueButton, bbbserver, nor the user can fully control.
Use Cases
- Accessibility — provide subtitles for participants with hearing impairments.
- Multilingual meetings — a captioner can provide subtitles in a different language than the one being spoken.
- Language barriers — subtitles can help non-native speakers follow the conversation more easily.