Path: utzoo!utgpu!watserv1!watmath!att!mcdchg!ddsw1!corpane!sparks
From: sparks@corpane.UUCP (John Sparks)
Newsgroups: comp.sys.amiga
Subject: Re: Compressed archive format
Keywords: chinese menu
Message-ID: <2793@corpane.UUCP>
Date: 29 Aug 90 17:12:22 GMT
References: <1990Aug25.180851.4401@zorch.SF-Bay.ORG> <1051@tau.sm.luth.se>
Organization: Corpane Industries Inc., Louisville, KY
Lines: 56


d88-mbe@sm.luth.se (Michael Bergman) writes:


>Benchmarks have been done. I have them on paper, but not in electronic format
>I'm afraid so I can't repost them. Because lharc is so slow, the guy who
>did this concluded that Zip is the overall most effective algorithm (I *think*)

The first version of Lharc for the Amiga was slow, but the latest versions
by Jonathan Forbes seem pretty fast. I have seen a version that just unpaks
called Lhunarc and a program that packs and unpacks called LZ.
Inside a doc file Jonathan gives this benchmark:

----excerpt from LZ .82 doc---

How fast is it [LZ .82]?
   Lightning fast.  If you've been using Lharc to compress or decompress files,
then you're in for a big surprise.  If you've been using Lhunarc 0.96 (also
written by me), and thought that was fast, then prepare yourself for some major
speed increases, because Lz is faster still!  Lz is between 16% and 25% faster
than Lhunarc 0.96, and that's no joke in terms of speed!

   I have pushed the decompression algorithm almost to its limits.  No other
.LZH extractor can even come -close- to Lz's decompression times.  Things
simply can't get much faster.  Yes, I know I said that in the Lhunarc 0.96
documentation too, but this time I'm pretty sure I'm almost at the limit!

   Here follows a small speed comparison.  The files being compressed and
decompressed were those on Fred Fish disk #245.

                      * - Different algorithm/encoding scheme

                                           *        *
             | (0.82)  | (1.0) | (.99d) | (1.01) | (1.40)
             |   LZ    | Lharc | LharcA | PkaZip | Lhwarp
Fish245.LZH  |  11:33  | 26:29 |    ?   |  10:31 |  13:43  <-- compressing
             |   1:47  |  5:12 |   2:34 |   2:53 |   2:51  <-- decompressing

   LZ certainly kills everything else dead, but is it faster than PkaZip?
Well, sometimes it is, but usually it isn't.  However, LZ (and Lharc, etc.)
almost always compresses files better than Zip.  For example, "MegRyan.lzh"
(a complete 655k digitised sound sample of the famous restaurant scene from
When Harry Met Sally), compresses from 655302 bytes to 488679 when LZ is used,
while the equivalent .zip file is 536773 bytes long.  LZ compresses the file
faster than Zip, too.
---end excerpt---

LZ .82 is shareware, but Lhunarc is freelware. Oh, BTW, the LZ and Lhunarc
beat the pants off of both Zoo and Arc at uncompressing.


-- 
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