Bad Apple case study

This is the end-to-end proof that the format and OTA work is correct. It is documented as a case study; no Bad Apple frames or prebuilt firmware are distributed here.

Why 9.ajs

9.ajs is the 8-second sport warm-up animation for sport type 22. It is small enough to replace without rebuilding the whole resource set:

	Stock 9.ajs	PoC
Frames	1,124	202
FPS	25	25
Duration	~45 s	~8.1 s
Size	4,795,064 B	756,479 B
Video	240×240	240×240

The PoC is silent, 240×240, baseline JPEG, and fits in a single-tile-per-frame layout.

Build outline

1. Extract res_e.bin from the stock AOTA image.
2. Extract 9.ajs, confirm the record layout and fps.
3. Encode 202 frames at 240×240/25 fps as baseline JPEG.
4. Repack with fwkit ajs-repack so the prelude and tile table are correct.
5. Verify: extract the new .ajs again and compare frame bytes.
6. Replace 9.ajs in res_e.bin with fwkit edit-sdfs (or rebuild SDFS and pad_to the original 58,777,088-byte partition).
7. Rebuild the AOTA image with fwkit pack; fwkit verify must pass.
8. Flash over BLE using the OTA guide.

Flash result

• The image was ~54 MB; the watch requested ~38.08 MB (70.4%) because unchanged partitions were skipped.
• The watch reported 0xA041 01; the client sent 0x9041 A5.
• It rebooted, booted the new image and played the animation in the UI.
• A second short transfer (1.63 MB, 3.0%) completed after the first had already staged most data; it also ended with the commit ack.

Capacity ceiling

Full Bad Apple at 5,250 frames is ~19.7 MB (~18.75 MiB). After replacing 9.ajs with the PoC, res_e has only ~3.85 MiB free. Options:

• deleting other warm-up .ajs files to reclaim space;
• lowering resolution/fps or using stronger JPEG compression;
• splitting the clip and swapping files (not supported by the stock UI);
• accepting a shorter excerpt.

res_e total is 58,777,088 B; stock usage is 58,776,014 B, so headroom is essentially zero unless content is removed.

Legal note

Bad Apple is copyrighted. Frames, a built .ajs and a firmware image containing them are not published. The method is described, the tooling is shipped, and the media is supplied by the user.