Live transcription and translation

You can receive speech as JSON objects, in real time, using the Zoom live transcription and translation feature (LTT). This feature can also translate speech from one language in real time to text in another language. This can power use cases like auto closed captioning, sentiment analysis, and language translation for e-learning.

For example, one user can say "Hello world" in English, and the other users can receive this speech, as text, in the language of their choice, like Italian "Ciao mondo", Spanish "Hola Mundo", and French "Bonjour le monde".

Zoom recommends that you provide an in-product notice to your end-users when a participant enables live transcription.

View usage

To monitor transcription (caption) and translation activity for your Video SDK sessions, see Build Platform → View usage reports: Captions and translation for detailed usage data.

Initialize LTT

After joining a session, call client.getLiveTranscriptionClient() to get the live transcription and translation client.

const liveTranscriptionTranslation = client.getLiveTranscriptionClient();

Supported languages

We are continuously adding to our supported languages for transcription and translation. To get the list of supported language, call liveTranscriptionTranslation.getLiveTranscriptionStatus(). The transcriptionLanguage property lists the supported languages.

liveTranscriptionTranslation.getLiveTranscriptionStatus();
  • To specify the language you are speaking in, call liveTranscriptionTranslation.setSpeakingLanguage().
  • To specify the language you want translated to, call liveTranscriptionTranslation.setTranslationLanguage().

The calls have to be promise chained or awaited. See start live transcription and translation for an example and samples scenarios for detailed use cases.

Start transcription and translation

To start live transcription and translation, call liveTranscriptionTranslation.startLiveTranscription().

liveTranscriptionTranslation.startLiveTranscription().then(() => {
    liveTranscriptionTranslation.setTranslationLanguage("ja");
    liveTranscriptionTranslation.setSpeakingLanguage("ja");
});

await liveTranscriptionTranslation.startLiveTranscription();
liveTranscriptionTranslation.setTranslationLanguage("ja");
liveTranscriptionTranslation.setSpeakingLanguage("ja");

Receive transcription

To receive speech text, add the following event listener.

client.on(`caption-message`, (payload) => {
    console.log(payload);
    console.log(`${payload.displayName} said: ${payload.text}`);
});

Receive translation

To receive translated speech text, add the following event listener.

client.on(`caption-message`, (payload) => {
    console.log(payload);
    console.log(
        `${payload.displayName} said: ${payload.text}, translated to ${payload.language}`,
    );
});

Stop live transcription and translation

To stop live transcription and translation, call liveTranscriptionTranslation.disableCaptions().

liveTranscriptionTranslation.disableCaptions();

Note: This disables the feature for all users in the session.

Sample scenarios

You don't need to use transcript and translation at the same time. Here are some sample scenarios that show the different use cases.

Scenario 1: Set speaking language with no translation enabled

The setSpeakingLanguage method specifies the user's spoken language. By default, this setting only applies to the user and does not affect others in the session. When no translation is enabled, users typically communicate in the same language. Any user can update their spoken language in the session.

// Set session-level speaking language
liveTranscriptionTranslation.setSpeakingLanguage(lang, {
    mode: TranscriptionMode.Session,
});

When the session-level speaking language changes, users receive the caption-status event.

client.on("caption-status", (payload) => {
    const { sessionLanguage } = payload;
    if (sessionLanguage) {
        console.log(`Session language has been changed to ${sessionLanguage}`);
    }
});

Restrict control to hosts

To restrict language changes to session hosts only, lock the transcription language setting.

liveTranscriptionTranslation.lockTranscriptionLanguage(true);

Scenario 2: Set translation language and enable translation

The setTranslationLanguage method sets the target language for translation. You can also set the speaking language and translation language to be the same (this is a common configuration). You can only call this method after you've enabled transcription.

// Enable transcription first, then set translation language
liveTranscriptionTranslation.startLiveTranscription().then(() => {
    liveTranscriptionTranslation.setTranslationLanguage("ja"); // Japanese
});

When you've enabled translation, users may speak different languages. In this case, setSpeakingLanguage only affects the individual user's spoken language, regardless of the mode:TranscriptionMode.Session option setting. Listen for the caption-status event when translation becomes available.

client.on("caption-status", (payload) => {
    const { translationStarted } = payload;
    if (translationStarted) {
        // Prompt users who haven't set their speaking language
        // to do so for better translation accuracy
        showLanguageSelectionPrompt();
    }
});

LTT best practices

When implementing Live Transcription and Translation (LTT) for your integration, consider the following best practices:

  • If the feature is enabled for the session, provide a button to allow people to start closed captioning and select the spoken and translated languages.
  • Display only the supported languages you wish to offer, rather than presenting all available options for transcription and translation.
  • If the session won't include LTT, programmatically disable when the host starts the session. When someone joins the session, check if the feature is enabled by the host. If not, inform users.
  • Use an event listener to detect when the host has enabled captions. You can use this to notify people that the feature is active, programmatically render a button for starting transcription or translation, or both.
  • Set enableReceiveSpokenLanguageContent() to false if you don't want to receive the spoken language data.
  • Use an event listener to detect when the host disables captions. You can use this to notify people who have enabled the feature that it has been disabled.
  • Offer closed captioning customization options, such as font sizes and colors, to differentiate between transcription and translation texts, to enhance readability and follow accessibility standards.
  • Inform people of these best practices when speaking:
    • Minimize background noise, avoiding activities like shuffling papers, typing loudly, or engaging in side conversations.
    • Speak clearly into the microphone.
    • Position the microphone near active speakers.
    • Opt for an external microphone over a built-in one to improve sound quality.

More LTT features

You can also control user audio volume and mute local audio to further refine live transcription and translation use cases.

For the full set of live transcription and translation features, see LiveTranscriptionClient in the Video SDK Reference.