raveling@Unify.com (Paul Raveling) (03/30/91)
I just tried an early version of LHarc (V0.03) and got
very disappointing results. Is a more recent version
available by email or by uucp? Is there reason to believe
a more recent version would improve this performance
substantially?
Alternatively, is there ANYTHING that provider about
the same degree of compression as Unix "compress" but
runs significantly faster than "compress"?
Here are the results, clipped from a script file of
running lharc and Unix compress on the same image file...
Speed:
$ time lharc c i.lharc i.p
i.p - Freezing :
....................................................................i.p
- Freezing :
ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooi.p
- Frozen(56%)
32.4 real 30.6 user 0.6 sys
$ time compress <i.p >i.p.Z
6.7 real 6.1 user 0.5 sys
[lharc was 5 times slower than standard "compress"]
File Size Last Modify UsrGrpOth Owner Group
---- ---- ----------- --------- ----- -----
i.lharc 470069 Today 09:30:46 rw.rw.r.. raveling staff
i.p 832882 Today 09:22:42 rw.r..r.. raveling staff
i.p.Z 443923 Today 09:31:11 rw.rw.r.. raveling staff
[lharc produce a file about 6% larger than "compress"]
------------------
Paul Raveling
Raveling@Unify.combrad@looking.on.ca (Brad Templeton) (03/30/91)
You are not likely to find anything that is much faster than compress, although one can find programs that compress better -- much better -- and at similar speed. The LZW algorithm was designed for speed -- designed to be implemented in hardware, even. So it would be a serious achievement to get something significantly faster. -- Brad Templeton, ClariNet Communications Corp. -- Waterloo, Ontario 519/884-7473
davidsen@sixhub.UUCP (Wm E. Davidsen Jr) (03/31/91)
Your speed results are about what I would expect. LHarc is slow. However
I think your old version is doing a poor job of compressing compared to
v1.x. Also you are comparing an archive with a compressed file, a
procedure which counts the header information against the archiver. For
image data I would expect the compressor only code from lharc, known as
freeze, to produce an output which is about 10-15% smaller than compress
on images, up to 40% smaller for some text files.
For very large images the 'compact' compressor does a good job, and it
is most definitely faster than compress.
--
bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
sysop *IX BBS and Public Access UNIX
moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -me