Fix common lip-sync artifacts
With a clean source video, Dubly.AI's Lip-Sync produces natural results out of the box. Almost every artifact you'll see traces back to a few specific extreme conditions in the footage — a mostly covered mouth, very steep camera angles, or a face that's too small in the frame. Here's how to spot them and what you can do.
When Lip-Sync works well
For most source videos, Lip-Sync looks natural without any extra setup. You'll get the best output when:
The speaker's mouth is clearly visible throughout
The face fills 10–40% of the frame
Lighting on the face is stable and even (no hard shadows on the mouth)
The footage is high resolution at a consistent frame rate (25 or 30 fps)
If your video meets these conditions and you still see artifacts, skip to the last section to contact support.
Edge cases that cause artifacts
Most artifacts come from a handful of extreme situations in the source. Check whether any of these apply to the affected segments:
Mouth is mostly covered. A hand, microphone, hair, or any object crossing the mouth mid-sentence breaks lip tracking. Even brief occlusions can glitch that segment.
Extreme camera angles. Pure profile shots or steep up/down angles give the model too little of the mouth to work with. Slight off-angles are fine — only the extremes cause issues.
Face too small in the frame. When the face takes up less than ~10% of the frame, lips often look smudged or "plasticky." The model needs enough pixels around the mouth to generate sharp movement.
Speaker turns away from the camera. Once the mouth isn't visible, the model can't track it. Brief turns are fine — extended off-camera moments cause artifacts at the transitions.
Variable frame rate or low resolution. Variable frame rate (VFR) causes timing drift, and low-resolution footage causes flickering teeth or unstable lips. Re-encode to CFR 25 or 30 fps H.264 at a high bitrate before re-uploading.
Hard shadows on the mouth. Strong shadows from overhead lighting or harsh sunlight can confuse the model about where the lips actually are.
What to do about it
If only specific segments are affected: Re-cut your source to remove or shorten the problem shots. The Lip-Sync result from a cleaner version of the same content will be noticeably better.
If your source footage can't be improved: Disable Lip-Sync for that video. For content where the speaker is off-camera most of the time, or where the mouth is rarely visible, the dubbed audio over the original lips often looks more natural than a forced Lip-Sync.
If you're planning a new shoot: Most issues can be avoided at the source.
Still seeing artifacts?
If your source video meets the quality bar above — clear mouth, good framing, stable lighting, consistent frame rate — and you're still getting artifacts, contact our support team with:
The dub link
A timestamp of the problem segment
A short description of the artifact (out of sync, smudged lips, frozen face, etc.)
This helps us investigate whether it's something we need to tune on our side.