After Effects Masking for Background Replacements

I need clean, precise masks created in After Effects so I can lift people or key objects out of several 4K shots and drop them onto completely new backgrounds. The sole goal is background replacement, so the mattes must hold up under color grading, subtle camera moves, and motion-blurred edges.

You’ll be working with ProRes footage and the replacement plates or video loops I supply. Rotobrush 2.0, manual spline refinement, motion tracking, and light-wrap tricks are welcome—whatever gives me a believable composite.

Deliverables I expect:
• The .aep file with clearly labeled comps and nondestructive masks
• A lossless alpha-channeled render of each masked element
• A quick H.264 preview showing the subject against the new background for review

Please tell me how many seconds of footage you can finish per day, outline your revision approach, and include links to past masking or background-swap work. Clean edges, consistent feathering, and accurate frame-by-frame coverage are the acceptance criteria.