Quick Answer
Most AI lip sync errors come from the two things you give the model, not from hidden settings. Audio driven lip sync models such as InfiniteTalk take only an image or video of the face and an audio file, so the fixes are there: use clean audio with one voice and no music, use a photo where the face fills at least a third of the frame with the mouth unobstructed, and avoid sharp head angles. If the timing drifts after rendering, the cause is usually the edit: keep the audio untouched and the project frame rate matched when you place the clip.
Checked 16 September 2026 against the input lists of InfiniteTalk Fast and InfiniteTalk, which take only a face image or video and an audio file.
Applicability: This applies to talking videos made from a photo or video and an audio file. It does not cover professional dubbing or broadcast post production.
Troubleshoot AI lip sync in the three places errors come from: the audio, the face image, and the edit afterwards.
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Related next steps
Advice about lip sync errors often tells you to adjust sensitivity, tweak animation speed or fix a rig. Most current tools have none of those controls. Audio driven models take two inputs, a picture of a face and a sound file, and everything that goes wrong traces back to one of them or to what happens afterwards in the edit. Checked against the models' own input lists on 16 September 2026.
First, know what you can actually change
On Percify, both InfiniteTalk Fast ↗ and InfiniteTalk ↗ list exactly two inputs: the audio file, and a face image or video. There are no timing, sensitivity or mouth shape settings. That is good news for troubleshooting, because it leaves only three places to look.
1. The audio
Lip sync follows the sounds it can hear, so anything that masks speech shows up in the mouth.
- Music or noise under the voice makes the mouth move to sounds that are not speech. Use a clean voice track, with music added afterwards in the edit.
- Two voices at once leave the model guessing which one the face should say. Give it one speaker per clip.
- Clipped or distorted audio blurs the consonants that close the lips. Record a little quieter.
- Long silences are where a mouth that keeps moving is most visible. Trim dead air before rendering.
2. The face
- The face is too small. It should fill at least a third of the frame; a distant or group photo does not carry enough mouth detail.
- The mouth is covered. A hand, a microphone, heavy shadow or hair across the lips gives the model nothing to animate.
- The head is turned sharply. A near frontal photo shows the whole mouth; a profile shows half of it.
- A video input moves a lot. If you supply video rather than a still, a steady clip with little head movement keeps the mouth in view.
If the timing is right but the mouth looks soft, that is resolution rather than sync: InfiniteTalk Fast renders at 480p for 2 credits a second, while InfiniteTalk renders at 480p for 4 credits a second or 720p for 1.5 times that.
3. The edit afterwards
Plenty of lip sync drift is introduced after a clean render:
- Do not change the audio after rendering. Replacing, speeding up or trimming the voice track inside the clip breaks the match the model made.
- Keep the project frame rate matched to the clip you import, so the editor does not drop or duplicate frames.
- Move audio and video together. Unlinking them and nudging one is the most common way a synced clip ends up late.
How to check a render in thirty seconds
Watch for three things, once at full speed with sound and once at half speed: the lips close on P, B and M; the mouth stops during silences; and teeth and tongue stay sharp at the start of words. If all three hold, the sync is fine and any remaining problem is in the edit. For comparing tools on the same test, see lip sync platforms compared and the best AI lip sync app; for sync on translated video, video translation problems and fixes.
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Frequently asked
Usually because of the audio or the face you supplied, or because of the edit afterwards. Music or a second voice under the speech, a small or covered mouth, a sharply turned head, or audio changed after rendering are the common causes.
There are no timing or sensitivity settings to adjust: InfiniteTalk Fast and InfiniteTalk take two inputs, an audio file and a face image or video. The fixes are cleaner audio, a better photo, and leaving the audio untouched in the edit.
A near frontal photo where the face fills at least a third of the frame and nothing covers the mouth, with even lighting across the lips. Distant, group or profile photos give the model too little to animate.
Because the clip was changed after rendering: the audio was replaced, retimed or unlinked from the picture, or the project frame rate differs from the clip. Keep audio and video linked and the frame rate matched.
Watch the render once at full speed and once at half speed. The lips should close on P, B and M, the mouth should stop during silences, and teeth and tongue should stay sharp at the start of words.
