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1. CrunkLord420 (crunklord420@clubcyberia.co)'s status on Saturday, 21-Dec-2024 08:43:25 JST CrunkLord420
   Nothing scratches that autistic itch like re-compressing my PSX and PSP library into CHD files.
   
   Yes, CHD gets a better compression than CSO. They added support for zstd for CHDs recently, but the default LZMA gets you a better ratio. For me, the ratio is more important.
   • iced quinnsmas :blobcatsanta: (icedquinn@blob.cat)'s status on Saturday, 21-Dec-2024 17:06:49 JST iced quinnsmas :blobcatsanta:

     in reply to

     • iced quinnsmas :blobcatsanta:
     @crunklord420 i spent a little while reading up on some of the algorithms and implementations. lzma's main contribution it turns out is something called 'optimal parsing,' where it basically does some minorly more elegant than brute force code checking because sometimes stringing together a couple individually suboptimal codes is more globally optimal, but is why its slow as shit
     
     zstd's main contribution is basically arithmetic coding (i think collet uses his own form of rANS or something similar to this) which squeezes out a little more than huffman (zip, lzma) at the expense of having a lot of performance bottlenecks
     
     apparently RoLZ followed by huffman is like, pareto optimal in that the whole system is some 1,000 SLOC and is within a few percent of either, lmao
     CrunkLord420 likes this.
   • iced quinnsmas :blobcatsanta: (icedquinn@blob.cat)'s status on Saturday, 21-Dec-2024 17:06:50 JST iced quinnsmas :blobcatsanta:

     in reply to
     @crunklord420 what did they set zstd to? it has a level 9 but its usually not used because the time investment grossly outweighs the gains.
   • CrunkLord420 (crunklord420@clubcyberia.co)'s status on Saturday, 21-Dec-2024 17:07:23 JST CrunkLord420

     in reply to

     • iced quinnsmas :blobcatsanta:
     @icedquinn not sure. I feel like if you need more than zstd level 3 (default) you should go to LZMA2.