On-device or cloud captions: which fits your event?
A neutral comparison of the two ways to caption and translate a live event, including when the cloud is the better choice.
On-device captioning runs the AI on a computer in the room; cloud captioning runs it in a remote data center. For in-person events, on-device avoids the dependence on venue internet. For remote audiences or human interpretation, cloud or human services can be the better fit. ConferenceCaptioning is an on-device system.
Side-by-side: how the two architectures differ
This compares the two approaches in general, not any single vendor. We have only benchmarked our own engines.
| On-device (ConferenceCaptioning) | Cloud-based services | |
|---|---|---|
| Where the AI runs | On the organizer’s own device in the room | In a remote data center |
| Internet during the event | Not needed for captions or translation | Required, and its quality sets the quality of the captions |
| Main source of delay | Local processing on the device | Network round trip plus processing, which varies with congestion |
| If the internet drops | Captions continue | Captions stop or degrade until it returns |
| Audio path | Stays in the room for captioning and translation | Streams to a third-party server |
| What you bring | A Mac, iPad or iPhone (or Windows with an extension), a screen or switcher, and a backup device; a router only for phones | Often only a browser and a good connection |
| Extra venue cost | None for bandwidth | May need a dedicated internet line, commonly about $2,500–5,000 for large events |
| Best for | In-person conferences, auditoriums, broadcasts, rooms with poor connectivity | Remote and hybrid audiences, events with no room for extra equipment |
When a cloud service is the better choice
We would rather you pick the right tool for your event.
Mostly remote audiences
If people watch from many locations, a cloud service reaches them without a local network.
No room for equipment
If you cannot place a device and a router in the room, a browser-only service is simpler.
Human interpreters or captioners
Legal, medical or regulated settings may require a certified person, which AI captioning does not replace.
What we have measured
Our evidence covers our own on-device engines.
On a live NASA news conference at real-time speed, the best engine scored 97.2% word accuracy, with captions in under a second and no internet needed. The data and scoring code are open: live captioning benchmark · multilingual translation benchmark. For setup without venue internet, see offline event translation.
Frequently asked questions
Is on-device captioning better than cloud captioning?
It depends on the event. On-device captioning is stronger when the event is in person, the internet is unreliable or expensive, or you want audio to stay in the room. Cloud services are stronger when most viewers are remote, when you want no hardware on site, or when you need a human interpreter or stenographer.
Does on-device captioning have lower latency than cloud?
It removes the network round trip, which is usually the part that varies. In our published benchmark, captions on a Mac appeared in under a second with no internet needed. We have not benchmarked other vendors, so we do not publish comparison numbers against them.
Where does the audio go with on-device captioning?
Speech recognition and translation run on the organizer’s device, so the audio does not need to be sent to a cloud service to produce captions.
What hardware do I need?
A Mac, iPad or iPhone for the captioning (a Windows PC can use our Chrome extension) and audio from your mixer. We recommend showing captions on the room’s screens. A router is only needed if attendees will also read on their own phones. A second device is recommended as a backup.
When should I choose a cloud captioning or interpretation service instead?
Choose cloud when your audience is mainly remote or hybrid, when you cannot place a device and a network in the room, or when you need a certified human interpreter or captioner for legal or regulatory reasons.
Try it at your next event
Start free in about 15 seconds, or book a demo and we will walk through your room, audio setup and languages.