AJS animations

.ajs files live in /NAND:E inside res_e.bin and are played by the sport warm-up view. They are not menu entries or watch faces.

Layout

0x00  magic/header
0x07  u8 fps (0 => 25)
0x08  records, one per frame:
        u16 size? / u16 tile_count?
        frame header / tile table
        JPEG tile stream(s)

The shipped files are 240×240, 25 fps, usually one tile per frame. Multi-tile frames use a tile table with (offset, length) pairs; offsets are relative to the descriptor magic.

Each record ends immediately before the next record; the last record ends at EOF. JPEG streams are ordinary baseline JPEG (FF D8 ... FF D9).

Tools

uv run fwkit ajs-info    work/res_e/9.ajs --frames
uv run fwkit ajs-extract work/res_e/9.ajs work/ajs9
uv run fwkit ajs-repack  work/ajs9 -o work/custom.ajs --fps 25
uv run fwkit ajs-set-frame work/custom.ajs 0 new_frame.jpg -o work/custom2.ajs

ajs-extract writes NNNN.jpg (or NNNN_TT.jpg for multi-tile frames). A matching repack is byte-identical for the shipped files.

Warm-up mapping

The app table at 0x101ED708 has 19 16-byte records: [sport_type, seconds, category, ajs_index]. All 19 .ajs files are warm-up animations. 9.ajs is sport type 22, an 8-second warm-up. See Watch faces & animations for the full table.

Capacity

The 202-frame PoC is 756,479 bytes (~3.7 KB/frame). Scaling to 5,250 frames gives ~19.7 MB (~18.75 MiB). res_e has only ~3.85 MiB free after replacing 9.ajs, so a full clip needs more deletions or a smaller encode.

Pitfalls

• 240×240 and a sane fps are kept; the player assumes the frame rate from +0x07 (0 means 25).
• Trailing bytes are not added after the last record; the last frame ends at EOF.
• Repacking goes through the toolkit rather than concatenating JPEGs; the record prelude and tile table must match what the player expects.
• The Bad Apple frames are copyrighted; no animation assets are included in this repository.