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Mouth lead: nudge performance tracks ahead of the clock

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Smoothing does not literally delay anything - a centred moving average has zero
phase lag - but it blurs onsets, so the visually salient moment of a mouth
opening moves later even though the mean does not. Animators also draw mouth
shapes a frame or two ahead of the sound as standard practice, so this is the
normal control rather than a workaround.

Only the performance tracks shift; the head and audio stay put, since it is the
mouth that should anticipate. In photo-underlay modes the vector mouth will
therefore no longer match the frame behind it, which is expected.

The lead is baked into the exported take - key f carries the pose from source
frame f+lead - so the Animator Pro renderer never needs to know about it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Your Name 2026-09-24 15:34:08 -04:00
parent a146d271b6
commit d18791e6ad
4 changed files with 64 additions and 14 deletions
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@ -57,6 +57,7 @@ is hand-drawn head plates, which this tool does not yet do.
| Knob | What it does |
| --- | --- |
| vertices | Lip vertex budget. The reduction past what the footage supports *is* the style. |
| mouth lead ±f | Shifts the performance tracks earlier against the audio and the head. `[` `]`. |
| contour avg ±f | Radius in frames. 0 off, 1 = ±1. Removes per-frame landmark jitter. |
| anchor avg ±f | Radius on the four similarity parameters. Smooths the *transform*. |
| closed-mouth cut | Aperture below which the mouth interior is emitted as `hidden`. |
@ -134,6 +135,14 @@ their own plate drawing. Everything starts kept; delete what you don't want.
**Suggest** runs error-tolerance decimation over head pose as a starting point,
then you hand-correct.
**Mouth lead** is not a correction for a bug. A centred moving average has no
phase lag, so smoothing does not delay anything — but it blurs onsets, and the
visually salient moment of a mouth opening moves later even though the mean does
not. Animators also draw mouth shapes one or two frames ahead of the sound as
standard practice. Only the performance tracks shift; the head stays with the
audio, since it is the mouth that should anticipate. The lead is baked into the
exported take, so the renderer never needs to know about it.
`contour avg` is a deliberate, bounded exception to "never smooth the contour" in
`../docs/roto-puppet.md`. That rule held while keys were sparse, because sampling
at velocity minima rejected detector noise for free. With a key on every frame it