Getting clean AI lip sync (sync. labs, Oct 2026): model choice and per-second prices, input checklist, long-video chunking and compositing colour tips

Primary vendor docs (extends the earlier lip-sync answer to curator request CA-DR-0001-07). Models and prices: sync-3 - 4K native output, built-in obstruction detection, extreme-angle support, full-shot processing ($0.107-$0.133/s); lipsync-2-pro - diffusion super-resolution detail for beards and teeth ($0.067-$0.083/s); lipsync-2 - best balance, preserves speaking style ($0.04-$0.05/s, recommended default); react-1 - adds emotion, expressions and head movement to match audio tone (clips up to 15 s). Video input: frontal/near-frontal face (lipsync-2/2-pro struggle with profiles; sync-3 handles extreme angles), even lighting, nothing covering the mouth (hands, mics, hair - or use sync-3), stabilised footage, one face or use Speaker Selection, >=480p (1080p recommended, up to 4096x2160), MP4/H.264. For compositing back onto source footage: export SDR BT.709 with explicit colour tags and H.264 yuv444p (not 4:2:0/4:2:2) to keep colours consistent. Audio: clean speech without music/noise (isolate vocals for songs), one speaker per track (Segments API for several), WAV/MP3, durations close to the video (sync_mode e.g. cut_off), any language. Known issues: long videos are processed in 30-40 s chunks, so quality can dip where a chunk boundary meets a turned/moving/absent face - cut at stable frontal moments; distortions mostly from harsh or uneven light; free/Hobbyist outputs are watermarked (removed from Creator plan up). Pairs with voice-consistency and dubbing tips (C3-B393-01, C3-B400-02) and consent rules for real people (C3-B432-01). Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Vendor guidance; not tested. Provider documentation as served 2026-10-23; models, limits, terms and prices change without notice. Limitations: Vendor guidance; prices change; not tested. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://sync.so/docs/compatibility-and-tips/improving-lip-sync-quality",
      "note": "Model Selection for Quality; Quality degrades in long videos; Preserve color metadata"
    }
  ]
}