Oh, but wait! Enabling searching for the best LZ77 window and pattern size (just in terms of 4 bits, 8 bits, 12 bits or 16 bits — not a completely free search) seems to put me at:
1: 256 x 141 : 4593 2: 256 x 141 : 5731 3: 256 x 192 : 8520 4: 256 x 192 : 8267 5: 256 x 192 : 9440 Currently a little worse than you for the Dizzys, a little better for the Flashbacks. I'm going to see if there's anything to gain from variable length LZ77 regions (at the minute it picks the predictor per line by trying every predictor with every combination of LZ77 length, then bundles together all the best predictors into a big block and LZ77s the whole lot, finding the best window/pattern size afresh for the whole lot). I guess I can look for patterns in the results of the line-by-line search. On Sat, Jul 31, 2010 at 2:04 PM, Thomas Harte <tomh.retros...@gmail.com> wrote: > Oh, but for the record, with what I think is a completely straight > reimplementation of PNG that isn't particularly intelligent in > searching for the smallest size: > > 1: 256 x 141 : 5190 (774 bytes worse than you) > 2: 256 x 141 : 6439 (826 bytes worse) > 3: 256 x 192 : 10041 (938 bytes worse) > 4: 256 x 192 : 9326 (732 bytes worse) > 5: 256 x 192 : 10599 (496 bytes worse) > > Which puts me, on average, about 10% worse than you. > > On Sat, Jul 31, 2010 at 1:33 PM, Thomas Harte <tomh.retros...@gmail.com> > wrote: >> Sadly I'm already doing that and still doing a lot worse than you. At >> this point I'd definitely suggest that if you're willing to donate >> code then it be used over anything I can come up with. >> >> I'm still trying though! >> >> On Sat, Jul 31, 2010 at 1:23 PM, Adrian Brown >> <adr...@apbcomputerservices.co.uk> wrote: >>> Oh one thing ive found out that may help in your tests. Dont compress >>> the data as nibble pairs. If you convert the data into bytes (only >>> using values 0 - 15) then compress that. (obviously in the decompressor >>> you need to patch it back so two bytes become one nibble). You may find >>> you get a much better compression rate. >>> >>> Adrian >>> >>> -----Original Message----- >>> From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] >>> On Behalf Of Adrian Brown >>> Sent: 31 July 2010 13:16 >>> To: sam-users@nvg.ntnu.no >>> Subject: RE: Dizzy (was:Porting spectrum games...) >>> >>> Ok, providing I havent made any mistakes on the compressor it looks like >>> the sizes are down at: >>> >>> 1: 256 x 141 : 4416 >>> 2: 256 x 141 : 5613 >>> 3: 256 x 192 : 9103 >>> 4: 256 x 192 : 8594 >>> 5: 256 x 192 : 10103 >>> >>> Ill write the decompressor and check, depends how slow it is to >>> decompress i guess ;) >>> >>> >>> >>> >>> >> >
