stabilizer-backend-change

name	stabilizer-backend-change
description	Use when changing Classic/Flow motion estimation, OpenCV backend selection, fallback behavior, or stabilization math.

Stabilizer Backend Change

Use this skill for work on feature tracking, dense optical flow, DIS/TV-L1, transform fitting, smoothing, crop handling, or fallback behavior.

Context

• Classic estimates sparse feature motion with OpenCV GFTT/LK.
• Flow normally uses OpenCV DIS optical flow.
• cv2.optflow is not available in standard OpenCV wheels; TV-L1 requires contrib OpenCV or an equivalent available API.
• Existing sample workflows use the Flow node.

Rules

• Do not assume cv2 or cv2.optflow exists unless declared and checked.
• If a stronger backend is unavailable, prefer safe fallback: perspective -> similarity -> translation -> identity.
• Keep fallback metadata auditable (flow_backend, applied transform mode, confidence/residual data where available).
• Preserve deterministic behavior for identical frames and inputs.
• Avoid GPU-only dependencies; this node is CPU-oriented.

Useful Checks

python3 scripts/validate_repo.py
python3 -c "import cv2; print(cv2.__version__, hasattr(cv2, 'DISOpticalFlow'), hasattr(cv2, 'optflow'))"

If using a ComfyUI venv, run the cv2 check inside that venv too.