Let me at my data! Pulling pictures out of an undocumented file format
summary
Reverse engineers an undocumented Fog of World file format and proves it contains 515-byte chunks (512 bytes of a 64×64 monochrome subtile plus three mystery bytes), uses hexdump + file + strings and custom ASCII-wrapping code to discover the 515/128 alignment trick, pins one mystery byte to ISO‑3166 country indexes, stitches decoded 64×64 tiles into larger maps and successfully exports images for wall art, while noting two trailing bytes remain unexplained.
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chapters (10)
- 0:00Reverse engineering a data file
- 1:04Undocumented file formats in Fog of World
- 2:50Visualizing raw data with ASCII
- 3:53Byte wrapping for patterns
- 4:57Metadata and track data assumptions
- 5:59Decoding 64x64 pixel subtitles
- 6:41Mystery of the last three bytes
- 7:42File naming conventions for tiles
- 9:06Open questions and future steps
- 9:48Tips from reverse engineering
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