Author: Dann Corbit
Date: 19:17:18 10/27/05
Go up one level in this thread
On October 27, 2005 at 22:12:55, Dann Corbit wrote: >On October 27, 2005 at 07:03:18, Yakov Konoval wrote: > >>On October 26, 2005 at 20:27:19, Dann Corbit wrote: >> >>>On October 20, 2005 at 10:56:15, Joshua Shriver wrote: >>> >>>>Interesting, a thought on compression though. Why not use bz2? It's just as easy >>>>to implement as zip and has better compression. >>> >>>Bzip2 is horribly slow, both for compressing and decompressing. >>> >>>The extra compression gained is a small percentage. Fine for web or ftp sites, >>>but (I guess) a bad choice for EGTB compression. >>> >> >>I did some experiments with bzip2-library. It's really slow, but gives much >>better (about 60-80%) compression in comparison with zlib-library. >> >>>7-Zip has lots of algorithms implemented (including bzip2.) The license is a >>>bit unclear to me. >>> >> >>AFAIK 7-Zip LZMA SDK has a very effective LZMA-algorithm, but using of this >>library is really unclear. Only 2 functions are needed for EGTB-generator- >>compression/decompression of 1 block in the RAM, but there are no such fuctions >>in lzma.dll. >> >>>This looks very interesting (although license is only GPL or commercial): >>>http://www.oberhumer.com/opensource/lzo/ >>> >>>What is wanted in a case like EGTB is very fast decompression and very good >>>compression. >> >>The main criteria for generation is very fast compression/decompression, but >>for the final study of generation the best compression is needed. > >What I would want from a set of EGTB files is the fastest possible access. >So if decomression of the block was slower than reading the decompressed block, >then the compression is literally "a waste of time." > >If you need provably the best compression, then look no further: >http://www.ii.uni.wroc.pl/~inikep/research/pasqda41b.zip > >According to this document: >http://www.maximumcompression.com/data/doc.php >pasqda41b achieved 1.3552 bits per byte against a large body of inputs. > >Comes with source code. But expect it to be a slow, slow memory hog. I looked up that program (pasqda41b), and it is designed for text files. So it probably won't work for EGTB files.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.