Which tool to choose
"Lip sync" is the synchronization of lip movement with an audio track. The choice depends on what you start from.
- You have a single photo and an audio, you want a talking face: Hedra. It's built precisely for the photo + audio flow, and it focuses on facial realism (natural expressions and head movements, not just the mouth).
- You want a character or a presenter in many languages: HeyGen, with many avatars and a great many languages. Handy for company videos and multilingual content.
- You need to dub an existing video into another language: a lip sync tool that realigns the speaker's lip movement to the new translated voice, so the dubbing doesn't feel off.
- You want maximum realism from a single image: lean toward those that put facial fidelity first, accepting longer generation times.
How to do it
From a browser or an app, the path is the same.
- Prepare the two ingredients. A photo or video of the face, well lit and front-facing, and the audio of the voice (recorded or generated with text-to-speech). The cleaner the two are, the more believable the sync.
- Upload photo and audio. Open the tool, upload the image or video of the face and the audio file.
- Generate the synchronization. The AI analyzes the speech and moves the lips accordingly. Some tools let you adjust sensitivity and timing: use them if the lip movement runs ahead or lags behind.
- Check the critical points. Look closely at the closed consonants (p, b, m): that's where wrong lip sync shows the most, because the mouth should close and sometimes stays open.
- Download and edit. Export the synchronized video and put it in your edit. Check that voice and image stay aligned for the whole duration.
There is no text prompt: the tool works on photo and audio. The control is the quality of the ingredients and the sensitivity and timing sliders.
A concrete example
Chiara has a video of herself explaining a product in Italian and wants to offer it in English too. She generates the English voice with text-to-speech from the translation of the script. Then she uploads the original video and the English audio to a lip sync tool, which realigns her lips to the new words. The result looks like Chiara really speaks English. She checks the mouth closures, adjusts the timing slightly, exports. In an hour she has the English version without reshooting the video.
When it does NOT work (and how to fix it)
If the lips don't close on the consonants
On p, b, m the mouth has to close: if it stays open, the effect is unnatural. Fix: adjust the sensitivity if the tool allows it, and start from a clear audio (weak consonants confuse the AI). If the problem persists, try a tool more oriented toward facial realism.
If the face deforms or looks rubbery
It happens with low-quality photos, badly lit or not front-facing. Fix: use a sharp image, with even light and the face turned toward the camera. Profile shots or dim-light photos give artificial results.
If voice and lips drift out of sync over time
On long clips the gap can accumulate. Fix: work on shorter segments and realign them in the editor, or use the tool's timing control to correct the drift before exporting.
If the watermark appears or the credits run out
The free plans give few generations and often brand the video. Fix: use the free one to try; for the final videos, a paid plan removes the watermark and raises the credits. Concentrate the paid generations on the definitive clips.
A tip from someone who actually uses it
Always start from the best voice you can get hold of. Lip sync is only as good as the audio you give it: a clear, well-articulated voice, with few uncertain pauses, produces clean lip movement; a confused voice full of hesitations throws the AI into a crisis. First take care of the audio (record it well or generate it carefully), then synchronize. The right order is sound first, image after.
Frequently asked questions
Can I use a person's face without their permission?
No. Making someone's face speak words they never said, without consent, is a serious practice: it violates their image and can amount to defamation or fraud. Use lip sync on your own face, on catalog avatars, or with the explicit consent of the person who appears.
Does lip sync dubbing replace professional dubbing?
For informal and company content it makes the dubbing believable at low cost. For cinema and content where the acting matters, human dubbing remains superior: the AI synchronizes the lips, it doesn't interpret the emotion of a line.
Do I need a starting video or is a photo enough?
A photo is enough to generate a talking face from scratch. If instead you start from an existing video, the tool realigns the lip movement to a new audio. These are two different uses, both supported by the main tools.
Can you tell a lip sync video is made with AI?
Less and less on polished content, but a careful eye still catches micro-flaws: imperfect mouth closures, slightly fixed expressions. Precisely because it's becoming convincing, it should be declared when it could deceive: passing off a synchronized video as real footage of a person, in a serious context, is dishonest. The technology is neutral; the use you make of it is not.