nx_vmotion.nx

nx_vmotion.nx -- sovereign BLOCK MOTION COMPENSATION: the core trick VP8/H.264 use to beat plain tile-delta. When the camera pans or a head moves, EVERY tile's pixels change (tile-delta would resend them all), but the content just SHIFTED -- so for each block we search the PREVIOUS frame for the best-matching block (minimum SAD = sum of absolute differences) and send a tiny MOTION VECTOR (dx,dy) + a small residual instead of the whole block. A pan that costs tile-delta ~100% of the frame costs motion-comp a few vectors + near-zero residual. Pure integer buffer ops (no FPU, no syscalls) -> wasm-friendly sender-side encode. license_tier: ORIGINAL