|Versions tested:||Jr1, sh8|
|Optimal parameters:||/m590 /o16|
PPMd program is file-to-file compressor, it is written for embedding in user programs mainly and it is not intended for immediate use. I was interested in speed and performance improvements of abstract PPM model only, without tuning it to particular data types, therefore compressor works good enough for texts, but it is not so good for nonhomogeneous files (executables) and for noisy analog data (sounds, pictures etc.). Program is very memory consuming, You can choose balance between execution speed and memory economy, on one hand, and compression performance, on another hand, with the help of model order selection option (-o).the program documentation
The sh-variants are based on PPMd Jr1 and are written by Eugene Shelwien. Changes include X86 filter, new range coder, etc.
The 16 configurations for sh variants were submitted by the author in April 5, 2009.
(Have info that should be added here? E-mail.)
sh6, sh7 disqualified: verify error with OS1.
|Ver||Rating||CPR||DPR||S.E.||R.E.||Ratio||C. kB/s||D. kB/s|
|-m256 -r1 -o8|
|/m256 /o8 /e /r|
|/m590 /o16 /r|
|/m590 /o6 /e|
|/m590 /o6 /e /r|
|/m590 /o6 /r|
|/m590 /o8 /r|