Name every file {order}_{width}_{NAME} — the width token (7 · 14) names the tile outright; the highest order stands first on the board.
Photo · PNG / WebP
7 × 11 vertical7:11 · 2240 × 3520
14 × 11 horizontal14:11 · 4480 × 3520
Export at the tile’s own aspect and FIT is full bleed — 320 px per lattice square; anything ≥ 2048 on the long edge is plenty.
Video · H.264 MP4 · Media Encoder
Length≤ 3 s · loops
7 × 11 vertical448 × 704
14 × 11 horizontal896 × 704
Frame ratesource · cap 30
ProfileHigh · 4.1
BitrateVBR 2-pass · 2–4 Mbps
Audionone — no track
These are the @2x sizes: one video pixel per screen pixel at 100% on a retina display — the same height for all three, since every tile is 11 squares tall. Exact by design, so no zoom headroom; a photograph may be exported generously because the program derives its own stores from it, but a clip plays exactly as uploaded and its export size is its final size.
No alpha in H.264 — export full-frame. Every dimension is a multiple of 16, so the encoder pads nothing.