Clownacy / clownlzss

Collection of compressors, built upon a small and simple graph-based LZSS framework.

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool

clownlzss is a lightweight, minimalist, graph-based LZSS framework. Also included are a collection of compressors which utilise the framework.

Formats supported by the supplied utilities include:

  • Kosinski - a compression format common to first-party Sega Mega Drive games

  • Saxman - a format used by Sonic the Hedgehog 2, to compress its sound engine and music data (is actually a lightly-modified version of Haruhiko Okumura's 1989 LZSS format)

  • Chameleon - a format that saw use in Kid Chameleon and Sonic the Hedgehog 2's "Nick Arcade" prototype

  • Rocket - a format used by Rocket Knight Adventures

  • Rage - a format used by Streets of Rage 2 (is actually RLE, not LZSS)

  • Kosinski+ - a modified version of Kosinski developed by the Sonic ROM-hacking community, which optimises the format for the Mega Drive's CPU, improving decompression speed at no cost to compression ratio

  • Faxman - a modified version of Saxman designed to produce smaller files when used to compress SMPS music data

  • Comper - another community-developed format, which is designed from the ground up with a focus on decompression speed on the Motorola 68000. This comes at a significant cost to compression ratio

clownlzss utilises graph theory to perform optimal compression: naive "greedy algorithm" compressors prefer to compress the longest runs possible, but this does not guarantee the best compression ratio. Graph-based compressors resolve this by creating an "LZSS graph" - a weighted directed acyclic graph where each node is a value in the uncompressed file, and each edge is an LZSS match. By using a shortest-path algorithm, this graph can be used to compute the ideal combination of matches needed to produce the smallest file.

This project is under the 0BSD licence.

About

Collection of compressors, built upon a small and simple graph-based LZSS framework.

License:BSD Zero Clause License


Languages

Language:C 88.7%Language:CMake 10.9%Language:Makefile 0.5%