How do you add lip sync to AI video?

Generate the video without dialogue first. Then run it through a dedicated lip-sync tool (HeyGen, Hedra, Sync.so) with your audio file. The tool re-animates the mouth to match the audio. For talking-head content from scratch, an avatar tool with built-in lip sync is faster than generating then post-syncing.

  • Video first (silent or mouthed). Lip-sync tool after.
  • Hedra, Sync.so and HeyGen lead lip-sync quality in 2026.
  • Avatar tools with built-in lip sync skip the stitching step.
  • Keep audio under 30s per clip for best alignment.

Two workflows

Workflow A (post-sync): generate any video with a person speaking or with closed mouth. Upload clip + audio to Hedra or Sync.so. The tool warps the mouth to match. Best when you already have b-roll of a real person.

Workflow B (avatar): start in an avatar tool (Klixor avatar, HeyGen) where you choose a face, paste a script, and the system generates a synced talking head end-to-end. Faster for pure talking-head content.

Common quality issues

Lip-sync tools struggle with profile shots, partial face occlusion, and rapid speech. Frame the face square-on, keep speech at conversational pace, and the result usually passes for human at first glance.

FAQ

Can Veo 3 lip-sync dialogue from a prompt?

Veo 3 can generate speech, but precise sync to your own audio is best left to dedicated lip-sync tools.