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FE11 Chapter file LZ77 compression [Resolved]


Vennobennu
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I've been making edits to Fe11 using DSLazy and Nintenlord's LZ77 compressor, and have run into an issue with re-compressing the file for chapter 14's units - bmap014. After uncompressing the file for editing, recompressing, and assembling the .nds with the edited bmap014, the game hangs when loading Chapter 14. This happens even if no changes are made to bmap 014.

Looking at the original and recompressed bmap014 in HxD, the two files are very diferent (not sure how to explain, but many bytes are not the same), and the recompressed file is two bytes larger. I'm thinking the bmap014 file is supposed to be fixed-length, and NL77C's (de)compression is producing a file that is larger than it ought to.

...But I'm not sure how to make it work properly. Any ideas?

Edited by Vennobennu
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Uhhh it might be LZ11 compression. Try a program called Puyo Tools (link or search on google). Check the first bytes (the header) of the file using a hex editor to determine the type (e.g. "standard" LZ77 has an 0x10 somewhere near the beginning, I've forgotten exactly), then edit it after. It can't be too hard since I've edited those files before (IIRC they include unit data or something though I'm not sure since once again, it's been way too long and I didn't do much of this to start with).

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I'm 99% sure it uses LZ77 compression; all of the other bmap files I've edited are LZ77 compressed and I've made small changes to them just fine. The data decompresses to an understandable format (ie is structured like the doc says, and is consistent with ingame); it's just this particular one which causes problems so far.

The file has a 0x10 byte right at the beginning like the other files. And yeah, they deal with unit data and AI.

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  • 2 years later...

LZF is conceptually very similar to LZ77. Generally speaking most modern compression algorithms give roughly the same compression, and with regard to the number of cores that you can use at once, it is up to you to decide how many you want to use. Generally speaking (unless you are creating large archives) there is no reason to need more than one though. In addition, with multiple cores doing the compression, the bottleneck may become the hard drive. Legacy zip compression is akin to the Deflate method in 7-zip, and will offer the most compatibility between different compression software.

John

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