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ulz

Namco's data compression method in Ace Combat 3, Ace Combat 51), and Time Crisis.

The Ulz format is an implementation of Lz77 algorithm with a ring buffer.

  • developed by Junichi Sakai
    • the Japanese Time Crisis executable contains the string ulz ver.1.00 J.Sakai
    • the Japanese Ace Combat 3 executable contains the string ulz decoder ver.1.05 programmed by Junichi Sakai 2)
  • archives begin with Ulz (55 6C 7A 1A hexadecimal, or 1A7A6C55 little endian)

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Timeline

  • 1995: Namco releases Time Crisis (ULZ 1.00)
  • 1999: Namco releases Ace Combat 3 (ULZ 1.05)
  • 2004: Namco releases Ace Combat 5 (ULZ 1.05)
  • 2011-01-04: modder McCuñao posts an incomplete description of ULZ “from a friend” 3)
  • 2012-03-11: modder Gipphe analyzes the format 4), but gives up – his texts and code is lost
  • 2012-06-20: modder CUE posts incomplete decompression code for Time Crisis and Ace Combat 3 5)
  • 2014-02-08: modder esperknight posts incomplete decompression code for Ace Combat 3 6)
  • 2014-08-02: esperknight posts full decompression code 7)
  • 2017-01-10: modder Infrid unites the two separate compression methods into one 8)
1)
[Projekt] Extracting Ace Combat, ZFX.info, https://zfx.info/viewtopic.php?f=10&t=4110&p=58277#p58277
2)
[asm Psx] Non Trovo La Routine, Romhacking, http://romhacking.it/forums/index.php?topic=605.msg5294
3)
Time Crisis 1 [PSOne] .ulz (LZR?), XeNTaX, http://forum.xentax.com/viewtopic.php?p=46917#p46917
5)
[PSX] Ace Combat 3 - I'm looking for help, Romxhacking, http://romxhack.esforos.com/post2916
6)
[PS1]ACE COMBAT 3: text replacement (Jpn.→Eng.), ROMhacking.net, http://www.romhacking.net/forum/index.php?topic=17658.msg256925#msg256925
7)
[PS1]ACE COMBAT 3: text replacement (Jpn.→Eng.), ROMhacking.net, http://www.romhacking.net/forum/index.php?topic=17658.msg264383#msg264383
8)
[Projekt] Extracting Ace Combat, ZFX.info, https://zfx.info/viewtopic.php?t=4110&p=53943#p53827
ulz.txt · Last modified: 2018/03/11 21:57 by krishty