User Tools

Site Tools


dreamcast:prs

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

dreamcast:prs [2019/12/12 21:25]
kion created
dreamcast:prs [2019/12/12 21:25] (current)
kion [Prs Compression]
Line 1: Line 1:
 ====== Prs Compression ====== ====== Prs Compression ======
  
-Prs is a form of compression often used in Sega games from the Sega Saturn (such as games like '​Nights into Dreams'​),​ heavily used in the Dreamcast era. And even still used in more recent games like Phantasy Star Portable. Prs compression is a compression format based on LZ77 compression. LZ77 is names after a set of papers published by Abraham ​**L**empel ​and Jacob **Z**iv ​in 1977. The compression and decompression approach they proposed was different from what was available at the time.+Prs is a form of compression often used in Sega games from the Sega Saturn (such as games like '​Nights into Dreams'​),​ heavily used in the Dreamcast era. And even still used in more recent games like Phantasy Star Portable. Prs compression is a compression format based on LZ77 compression. LZ77 is names after a set of papers published by Abraham ​Lempel ​and Jacob Ziv in 1977. The compression and decompression approach they proposed was different from what was available at the time.
  
 For the time, more compression was focused around making a code book of commonly used patterns is a set of data. So all of the data would need to be read once, and then analyzed for common patterns that repeat enough times to create a code book which would be a table of all of the common patterns and then the data would be encoded with a list of indices that refer to positions in the code book.  For the time, more compression was focused around making a code book of commonly used patterns is a set of data. So all of the data would need to be read once, and then analyzed for common patterns that repeat enough times to create a code book which would be a table of all of the common patterns and then the data would be encoded with a list of indices that refer to positions in the code book. 
dreamcast/prs.txt ยท Last modified: 2019/12/12 21:25 by kion