AI Dubbing Lip-Sync Compared: Who Publishes What, and What to Test
No dubbing vendor publishes a lip-sync accuracy rate. Here is who lists lip-sync, who prices it, who gates it to enterprise, and how to test a dub before you buy.
If you need lip-sync with a published price, Synthesia is the only vendor in this run that states a billing multiplier: twice the credits. Rask AI lists lip-sync, Captions lists AI Lipdub, and Dubverse puts it in Enterprise. The rest either do not mention it on the plan page or describe something adjacent. That is the honest state of the public record. It is thinner than the marketing suggests.
This post is part of our 2026 dubbing evaluation. It covers what lip-sync is, which vendors disclose it, and how to test a dub without relying on a demo reel.
What lip-sync actually does
A dub replaces the dialogue track. Lip-sync adjusts the mouth region so the new track appears to come from the speaker. The two jobs are separate: a vendor can translate accurately and still produce a mouth that lands half a syllable late.
Lip-sync also has a cost. It usually requires frame-level processing, and some tools charge for it separately because it is the most compute-heavy part of the pipeline. That is why the billing line matters as much as the feature line.
The disclosure table
| Vendor | What the plan page states | What it does not state |
|---|---|---|
| Rask AI | lip-sync listed | accuracy, cost per minute |
| Synthesia | lip-sync at 2x credits | accuracy, shot limitations |
| Dubverse | lip-sync in Enterprise | whether it is included or metered |
| Captions | AI Lipdub listed | which tier includes it |
| HeyGen | not stated in the fields we checked | the whole feature line |
| ElevenLabs | not stated in the fields we checked | the whole feature line |
| Descript | not stated | the whole feature line |
| VEED | not stated | the whole feature line |
| Papercup | XLPT prosody transfer, human validation | mouth alignment specifically |
| Deepdub | not stated | the whole feature line |
Papercup deserves a note. Cross-lingual prosody transfer is about rhythm and intonation, not mouth shapes. It can make a dub sound more natural without touching the lip region. That is a different promise, and it should not be counted as lip-sync.
Why there is no accuracy number
A lip-sync score would have to specify the shot, the language pair, the speaker’s mouth visibility, and the amount of occlusion. A close-up of a still face is easy. A profile shot with a hand near the mouth is hard. A single percentage across those conditions would be misleading.
So this site scores disclosure, not accuracy. A vendor that lists lip-sync and prices it earns credit on the 20% dimension. A vendor that stays silent earns nothing for that field, even if its product has the feature. That rule is harsh on good products with thin documentation, and it is the only rule that keeps the comparison checkable.
How to test a dub in an afternoon
Use one clip, 20 seconds, with four shots:
- A close-up, still face. This is the easiest case and the baseline.
- A profile or three-quarter turn. Mouth visibility drops; sync errors show up fast.
- A hand or microphone near the mouth. Occlusion is where many pipelines fail.
- A fast line with plosives. Watch the jaw and the release of “p”, “b”, and “m”.
Send the same clip to each vendor with the same target language. Compare the four shots, not the highlight reel. Then ask two questions: what happens when a shot fails, and what a re-render costs.
What to ask before you buy
- Is lip-sync included in the plan, or metered separately?
- If it is metered, what is the rate in credits or minutes?
- Is there a shot-length limit or a resolution limit?
- Does the vendor re-render a failed shot, and at what price?
- Does the licence cover the lip-synced output in the same way as the audio?
The last question is the one buyers forget. A lip-synced video is a new audiovisual asset, and the voice rights and the likeness rights both apply. A plan page rarely answers it.
Where this leaves the ranking
Synthesia’s 2x credit line is the clearest lip-sync disclosure in the run, which is one reason it sits third overall. Rask AI’s listed feature and Captions’ AI Lipdub keep them competitive on the dimension. Dubverse’s Enterprise gate is a clear signal to small teams: the self-serve plan is not the lip-sync plan.
If lip-sync is the deciding feature, start with those four vendors and test the four shots. If it is a nice-to-have, do not let a feature line outrank language coverage and a usable price.
The complete order for 2026 is published here; the methodology explains the scoring.
FAQ
Which AI dubbing tools publish lip-sync?
In this run, Rask AI lists lip-sync, Synthesia bills it at twice the credits, Dubverse places it in Enterprise, and Captions lists AI Lipdub. HeyGen, ElevenLabs, Descript, VEED, Papercup, and Deepdub do not state lip-sync in the plan fields we checked, although Papercup describes prosody transfer rather than mouth alignment.
Is lip-sync the same as translation?
No. Translation changes the words; lip-sync changes the mouth movement so it matches the new audio. A dub can have an accurate translation and poor sync, or a loose translation and convincing sync. They are separate quality questions and should be tested separately.
Why does no vendor publish a lip-sync accuracy score?
Because there is no shared benchmark. Accuracy depends on the shot, the speaker's mouth visibility, the language's phonetics, and the amount of head movement. A single percentage would hide those variables. This site records whether lip-sync is listed and how it is priced, and does not invent an accuracy figure.
How should I test lip-sync before committing?
Send the same 20-second clip to each vendor: one close-up, one profile, one shot with a hand near the mouth, and one fast line. Watch the consonants and the jaw, not the overall impression. Then ask whether the vendor offers a re-render when a shot fails, and what that costs.