Closed captions

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Closed captions play a critical role in video voice calling apps, providing numerous benefits that enhance the accessibility, usability, and overall user experience of these platforms.

In this article, you learn how to enable closed captions scenarios using the UI Library. There's two main scenarios to enable closed captions: Azure Communication Services video and voice calls and Interop calls.

Azure Communication Service based captions

Supported for calls involving Azure Communication Service users only. Currently, Azure Communication Service captions do not support language translation.

Teams Interop closed captions

Supported during calls with one or more Teams users.

Translation support

Unlike Azure Communication Service closed captions, Teams Interop closed captions support translation. Users can opt to have closed captions translated into a different language through the captions settings.

How to use captions

Captions are seamlessly integrated within the CallingUILibrary.

1. Activate captions:

   • During a connected call, navigate to the control bar and click the more button.
   • In the menu pop-up, toggle to turn on captions.

2. Adjust spoken language:

   • If a different language is being used in the meeting, users can change the spoken language via the UI. This change applies to all users in the call.

3. Set caption language (for Teams Interop Closed Captions):

   • By default, live captions are displayed in the meeting or event spoken language. Live translated captions allow users to see captions translated into the language they’re most comfortable with.
   • Change the caption language by clicking on the Captions language button after captions start, if translation to a different language is desired.

Note

Live translated captions in meetings are only available as part of Teams Premium, an add-on license that provides additional features to make Teams meetings more personalized, intelligent, and secure. To get access to Teams Premium, contact your IT admin. More details you can find it here.

Supported languages

Azure Communication Services supports various spoken languages for captions. The next table contains the list of supported language codes that you can use with the setSpokenLanguage method to set the desired language for captions.

Language	ACS Spoken Code	Teams Spoken Code	Teams Captions Code
Arabic	ar-ae, ar-sa	ar-ae, ar-sa	ar
Danish	da-dk	da-dk	da
German	de-de	de-de	de
English	en-au, en-ca, en-gb, en-in, en-nz, en-us	en-au, en-ca, en-gb, en-in, en-nz, en-us	en
Spanish	es-es, es-mx	es-es, es-mx	es
Finnish	fi-fi	fi-fi	fi
French	fr-ca, fr-fr	fr-ca, fr-fr	fr, fr-ca
Hindi	hi-in	hi-in	hi
Italian	it-it	it-it	it
Japanese	ja-jp	ja-jp	ja
Korean	ko-kr	ko-kr	ko
Norwegian	nb-no	nb-no	nb
Dutch	nl-be, nl-nl	nl-be, nl-nl	nl
Polish	pl-pl	pl-pl	pl
Portuguese	pt-br	pt-br, pt-pt	pt, pt-pt
Russian	ru-ru	ru-ru	ru
Swedish	sv-se	sv-se	sv
Chinese	zh-cn, zh-hk	zh-cn, zh-hk	zh-Hans, zh-Hant
Czech	—	cs-cz	cs
Slovak	—	sk-sk	sk
Turkish	—	tr-tr	tr
Vietnamese	—	vi-vn	vi
Thai	—	th-th	th
Hebrew	—	he-il	he
Welsh	—	cy-gb	cy
Ukrainian	—	uk-ua	uk
Greek	—	el-gr	el
Hungarian	—	hu-hu	hu
Romanian	—	ro-ro	ro

Ensure the spoken language selected matches the language used in the call to accurately generate captions.

Prerequisites

• An Azure account with an active subscription. Create an account for free.
• A deployed Communication Services resource. Create a Communication Services resource.
• A user access token to enable the call client. Get a user access token.
• Optional: Completion of the quickstart for getting started with the UI Library composites.

Set up the feature

Enable closed captions

The method setCaptionsOn is configured to start captions by default.

Kotlin

Kotlin

val captionsOptions = CallCompositeCaptionsOptions()
captionsOptions.setCaptionsOn(true)
captionsOptions.setSpokenLanguage("en-US")

val localOptions = CallCompositeLocalOptions()
localOptions.setCaptionsOptions(captionsOptions)

Java

Java

CallCompositeCaptionsOptions captionsOptions = new CallCompositeCaptionsOptions();
captionsOptions.setCaptionsOn(true);
captionsOptions.setSpokenLanguage("en-us");

CallCompositeLocalOptions localOptions = new CallCompositeLocalOptions();
localOptions.setCaptionsOptions(captionsOptions);

Enable closed captions

The method captionsOn is configured to start captions by default.

Swift

let captionsOptions = CaptionsOptions(
    captionsOn: true, 
    spokenLanguage: "en-US"
)

let localOptions = LocalOptions(
    participantViewData: participantViewData,
    setupScreenViewData: setupScreenViewData,
    cameraOn: false,
    microphoneOn: false,
    skipSetupScreen: false,
    audioVideoMode: .audioAndVideo,
    captionsOptions: captionsOptions
)

Next steps

• Learn more about the UI Library