Live Multilingual AI Subtitles

Clevercast lets you add very accurate closed captions in multiple languages, through the latest AI technology. The result is a global live stream with multilingual closed captions that can be watched on every device and platform.

Man holding laptop AI subtitles

Revolutionizing live closed captions with AI

Clevercast’s unique solution allows you to vastly improve the accuracy and readability of closed captions during a live stream, compared to all other solutions on the market. For the first time, you can simply rely on AI to add highly accurate multilingual captions to your live stream. You can even reach 100% accurate captions with minimal effort, by using our acclaimed real-time correction interface in the cloud. We can also provide real-time correctors for you.

Get accurate closed captions in your live stream STT

AI converts the live stream audio to closed captions


Our leading Automatic Speech Recognition (ASR) technology generates 99+% accurate captions. It supports any language, including streams with multiple languages.

Clevercast Learning

Enhance captions with real-time editing and vocabularies


Users can (optionally) edit the AI generated captions in real-time, before they are translated and streamed. Keyword vocabularies improve recognition and accuracy of specific terms.

Get accurate closed captions in your live stream TTT

AI translates the captions into any number of languages


Our top-tier AI language models let you add closed captions in multiple languages cost-effectively. With accurate source captions, expect top-notch translation quality.

Trusted by global brands and companies

AI Powered Live Subtitling

Auto-generate live stream subtitles with the highest accuracy

For an indication of the difference in accuracy and readability with other platforms, we recorded the same live stream with auto-generated closed captions in Clevercast, YouTube and Vimeo.

The live stream featured a number of different speakers, each with their own speech pattern and accent. All closed captions are entirely AI-generated, without any enhancement. All recordings are unedited.

Want to try it out yourself? Sign up for a free trial or contact us.

The live stream used excerpts from the following videos available June 20, 2023 under a CC-BY 4.0 license:
Paywall: The Business of Scholarship by Jason Schmitt
Will saving poor children lead to overpopulation? Free material from WWW.GAPMINDER.ORG

Unique AI Technology

Clevercast’s revolutionary contextual AI technology leverages the latency that comes with the HTTP Live Streaming protocol. By slightly increasing it, Clevercast has set a new standard for multilingual closed captions that are automatically generated and translated by AI engines.


Automatic speech-to-text conversion and translation

Clevercast ensures that ASR and AI services have a more comprehensive context at the time of speech-to-text conversion and text-to-text translation. This results in significantly greater accuracy.


Innovative audio pre-processing

Clevercast does pre-processing to send optimal audio input to the AI engines, like intelligently detecting audio fragments, improving the sound quality, reducing background noise…


Intelligent AI output processing

Intelligent post-processing allows for correcting spelling, adjusting punctuation and filtering hesitation words. It is also crucial to ensure that captions are easily readable (text length, number of lines, time shown).


Best-in-class language models

AI keeps evolving, almost on a daily basis. We benchmark different AI solutions, so Clevercast can automatically select the best engine on the market when a live stream is configured.

Provide more context by increasing HLS latency

Language models are predictive by nature. By slightly increasing the latency of the HLS stream, Clevercast is able to send more context to the ASR engine, which leads to correct predictions and better speech to text conversion.

Perfect synchronization of captions and video

Before being streamed, the captions have to be aligned again with the spoken words. Proper synchronization ensures that the captions appear at the right time and long enough to help viewers follow and understand the narrative.

Enhanced AI: perfect subtitles with human intervention

In the past, generating multilingual closed captions required human transcription for each language, which was not only costly due to the need for multiple human transcribers, but also resulted in inconsistent quality and inaccuracies. The quality of captions was largely determined by the expertise of transcribers and the characteristics of the stream, like speaking pace and audio clarity. Finding capable real-time captioners was (and still is) a challenge.

Clevercast Enhanced AI is the answer. Our advanced AI technology generates consistently accurate closed captions through intelligent speech-to-text conversion. With a web interface for editing captions in real-time, before they are translated and streamed, it becomes easy to produce superior multilingual caption quality in a cost-effective manner.


Superior subtitle accuracy through real-time correction

Clevercast offers an intuitive web interface that lets users edit the AI-generated captions in real-time. This, of course, leads to superior quality of the subtitles. It’s significantly easier for a person to correct minor errors in high-quality subtitles than to create them from scratch.


Cost-effective, no matter how many languages

Unlike human transcription, Clevercast Enhanced AI requires only one or two correctors, regardless of the number of languages. Since the corrected captions are used as a source for AI text-to-text translations, the quality of all caption languages is assured.


Closed captions perfectly in-sync with the live stream

Because captioning and correction all happen in our web application, the captions can be perfectly aligned with the spoken words. If desired, a real-time corrector can fine-tune this process by adjusting which words appear on a caption line, ensuring optimal readability and precision.


Smart AI Vocabularies ensure correct names and technical jargon

AI Vocabularies help to maintain the precision of speech-to-text conversion and translations. They guarantee a correct rendition of common terms and relieve the workload of the real-time corrector, since frequent terms need to be modified only once.

This tutorial shows how to use the correction room. Alternatively, you can source professional correctors from us.

How to do real-time editing

Web interface to edit incoming captions and UPDATE AI VOCABULARIES

Clevercast provides an intuitive web interface that lets you read and modify the AI-generated captions in real-time. It is designed for both first-time users and experienced editors, using a normal keyboard and mouse.

Users can make text corrections without any training, move text to other lines or temporarily stop captions from appearing. Advanced users can use shortcuts.

Due to the high quality of our language models, only a limited number of corrections is needed.

Closed captions as a Managed Service or SaaS Solution

Clevercast can be used as a SaaS platform. For those who prefer it, we also offer it as a managed service. We partner with leading language service providers to source professional closed caption correctors. We can provide them for most languages and subjects, if requested in a timely manner.

Self-Service Solution

Clevercast is a SaaS platform, allowing you to to use our AI solutions independently. You can also hire live correctors yourself. We can offer premium support for a guaranteed response time and service level.

Managed Service

We can source AI correctors, help you manage the event and provide assistance during the live stream. This way, we ensure an optimal viewing experience with closed captions of the best possible quality.

Multilingual live closed captions through AI translations

Clevercast supports automatic conversion of a single closed caption language into any number of languages. This way, you can easily make your live stream accessible to global audiences without high costs. Since Clevercast is able to generate a flawless source for the AI translation, you can count on exceptional caption quality.


Best value for money

Since the quality of the initial closed captions is good, their AI translations will also be accurate. This is a lot cheaper than using human captioners for each language, since you save significant labour costs.


Support for custom translations of specific terms

AI Vocabularies allow you to define your own translations for specific names or terms. This can be done both in advance and during the live stream, by a real-time corrector.


Deliver translations as extra audio languages

The text that is generated for the closed captions can also be used to add AI speech translations to the same live stream, without extra cost. Viewers can select both audio and caption languages in the player.

Multilingual video player

Viewers, anywhere in the world, can watch the live stream and select their preferred caption and audio language in our customizable HTML5 player, which can be embedded into any device and platform.


Maximize readability for viewers

Clevercast adds the captions to the live stream in an intelligent manner. This allows the video player to show synchronized sentences, rather than scrolling words. This makes the captions much easier to read and understand.


Any number of languages

Clevercast uses the best-in-class AI technology. Translation accuracy is also very good for less popular languages. Almost every language on the planet is supported.

Why choose Clevercast?

Extensive feature set

Clevercast has all necessary features for live and on-demand video streaming, management, distribution, monetization and analytics. Whatever your project needs are, we’ve got you covered.

Our customizable HTML5 player can be easily embedded into any device and platform. Just copy the embed code from Clevercast.

Combine with simultaneous interpretation

Closed captions can be added to any live stream with on-site or remote simultaneous interpretation. Viewers can choose both an audio translation and closed caption. Transcribers can listen to the audio translations in real-time.

Branded multilingual video player

Our responsive HTML5 player can be styled as desired. It allows you to display a poster image before the livestream, show interactive messages in an overlay, and much more. Works perfectly in any browser on desktop and mobile.

Full live stream redundancy

Clevercast supports a fully redundant set-up. Our player automatically detects if the main stream becomes unavailable and switches to the backup stream. This way, the live stream won’t drop out if there is an encoder or local network issue.

Cloud recording

Clevercast makes a server-side recording of the multilingual live stream, which can be downloaded. All caption languages can be downloaded as WebVTT files. This allows you to upload them to YouTube or social media channels for on-demand viewing.

Limit stream accessibility

You can determine who can watch your live stream by configuring white and blacklists for countries, domains and IP addresses. Different settings are possible for each live stream.

Detailed analytics

Our dashboard informs you in real time how many viewers are watching and from which country. After the live stream ends, it provides detailed insights into the behaviour of your viewers.

Conversion to Video on-Demand

The cloud recording of your live stream can easily be converted to Video on-Demand. The VoD player with closed captions can be added to your site or platform by just copying the embed code from Clevercast.

Frequently Asked Questions

What is the accuracy of automatic speech-to-text conversion?

The accuracy of speech-to-text conversion has improved drastically, thanks to the use of the best AI and ASR technology on the market.

AI-powered captions are 99+% accurate for commonly used languages like English, Spanish, French, German, Italian, Portuguese, Dutch, Japanese and others. For less common languages, the accuracy will be somewhat lower.

Factors such as speaking speed, articulation and dialect of the speaker or word usage like jargon and acronyms only reduce accuracy in extreme cases (and only to a very limited extent).

Even though the accuracy is very high, there is always room for improvement. You can do this by using a human operator to make just-in-time corrections to the AI-generated captions. The operator doesn’t have to be a professional or someone with experience in the matter.

We expect the accuracy of speech-to-text to continue to improve in the near future. The best-of-class ASR technology used by Clevercast is constantly evolving.

How many closed caption languages are possible?

Unlimited. In practice, it depends on your plan.

Can Clevercast can generate subtitles for a stream in which multiple languages are spoken?

Yes, see our demo and this tutorial for more info.

Can Clevercast provide live correctors for my event?

Yes. We partner with leading language service providers to source professional real-time correctors. We can provide them for most languages and subjects, if requested in a timely manner.

Is it possible to combine closed captions with audio translations in the same live stream?


Do live streams with closed captions have a delay? Are captions always in sync with the audio?

If you use AI-powered captions, the live stream has a delay of about one minute, which is slightly higher than the normal latency in the HTTP Live Streaming (HLS) protocol. This is necessary to improve accuracy and readability of the captions and allows for near real-time correction.

However, we are working on a low-latency version of AI closed captions.

No matter what the delay is, captions are always in sync with the video and audio of the live stream.

Can the look and feel of captions in the player be adjusted?

Yes, this is possible to some extent.

Can captions be displayed outside of the video player?

Yes. It is possible to embed a separate widget, together with the player. In the widget, the captions are shown as continuous text.

Are the live captions recorded? Can they be downloaded afterwards?

Yes, all live captions are recorded in the cloud. You can download them afterwards as WebVTT files. Or you can publish a Video on-Demand with captions, hosted by Clevercast.

What are the costs? How can I order?

If you are using Clevercast as a SaaS solution (without premium support), see our pricing page for reference.

If you want us to find live correctors, please contact us well in advance and describe your needs in some detail. After a virtual meeting (usually), we will provide you with a quote. The cost depends greatly on the duration of the live stream. Also keep in mind that professional correctors usually work in pairs.

What are 'AI hours'? How are they calculated?

AI hours are used when closed captions or audio translations are generated by speech-to-text conversion, text-to-text translation, or text-to-speech conversion. Usage depends on every set of 8 AI languages. For example, if you broadcast during 1 hour to a single streaming server and have 3 caption languages that are automatically generated, you will use 1 AI hour. If you stream with 10 AI caption languages, you will consume 2 AI hours.

Please note that this is based on the number of hours you broadcast to Clevercast. So AI hours will also count while your event status is ‘preview’ or ‘paused’.

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