Each participant in the meeting can independently enable closed captions in the language they want to see the spoken content. In effect, all participants can enable captions in different languages at the same time enabling them to read spoken content in their own native language within same meeting.

anchorUsing Closed Captions

To use the closed caption functionality of the iOS Meetings SDK:

1. Check if Closed Captions are allowed

Before using closed captions during a meeting, ensure they are allowed in the meeting in progress to avoid any issues:

var isAllowed = call.isClosedCaptionAllowed

2. Check if Closed Captions are enabled

Check if closed captions are enabled for the current meeting:

var isEnabled = call.isClosedCaptionEnabled

3. Toggle Closed Captions

Use a toggle to turn closed captions on or off during a meeting. The CompletionHandler indicates if the operation was successful or not.

You should rely on the onClosedCaptionsInfoChanged callback when captions are enabled to get the latest information updates:

call?.toggleClosedCaption(enable) {
    if (it.isSuccessful) {
        // captions toggled successfully
    } else {
        // toggle failed
    }
}

4. Observe Closed Captions Info Changes

To get the latest Closed Captions info for current spoken language and translation language, implement a CallObserverInterface.onClosedCaptionsInfoChanged() callback. Make captions are allowed and enabled:

call?.setObserver(object : CallObserver {
    override fun onClosedCaptionsInfoChanged(closedCaptionsInfo: ClosedCaptionsInfo) {
        // Use this callback to update UI for Spoken or Translation language
    }
})

5. Retrieve Closed Caption Information

Use the getClosedCaptionsInfo method to retrieve the closed captions info object, which contains information such as the current spoken and translation languages. Captions need to be enabled to use this method:

val ccInfo = call?.getClosedCaptionsInfo()

6. Set the Spoken Language

In instances that require a change in the spoken language, use the setSpokenLanguage() method. However, it's crucial to note that only the host can change the spoken language to ensure controlled communication flow:

call?.setSpokenLanguage(languageItem.code ) {
    if (it.isSuccessful) {
        // spoken language changed successfully
    }
}

7. Set the Translation Language

Use the setTranslationLanguage method to change the language of closed captions. This method specifies the language in which the text is displayed to the application:

call?.setTranslationLanguage(languageItem.code ) {
    if (it.isSuccessful) {
        // translation language changed successfully
    }
}

8. Access All Received Closed Captions

Retrieve a complete list of all closed captions from the start of the meeting to the present, allowing users to view previous captions:

val captionItems = call?.getClosedCaptions()

9. Manage Incoming Closed Captions

Implement a CallObserverInterface.onClosedCaptionsArrived() callback to manage and show new Closed Captions as they arrive during a meeting:

call?.setObserver(object : CallObserver {
    override fun onClosedCaptionsArrived(captions: CaptionItem) {
        // Show your captions here
    }
})

anchorCaptionItem Details

The CaptionItem object holds the caption text, speaker ID, display name, and an isFinal flag. The onCaptionArrived() method triggers initially with each spoken word (isFinal=false). When the speaker pauses or stops, it refines the text for accuracy and context, triggering again with isFinal=true. The isFinal=true flag indicates that the sentence is complete.

For example the following spoken phrase, "Hello developer, how are you?" can trigger the following callbacks:

1. Callback 1: "hello" -> isFinal=false
2. Callback 2: "hello developer" -> isFinal=false
3. Callback 3: "hello developer how are" -> isFinal=false
4. Callback 4: "hello developer how are you and" -> isFinal=false (The word "and" was a false detection.)
5. Callback 5: "hello developer, how are you?" -> isFinal=true (If the speaker pauses or stops talking. Normalized statement in terms of context and grammar.)